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The clinical value of hormone receptor assays in malignant disease
Car~er Treatment Reviews (1978) 5, 185--194-
T h e d i n i c a l v a l u e o f h o r m o n e r e c e p t o r a s s a y s in malignant disease M i c h a e l A. F r i e d m a n , * p h i l i p G. I ~ o f F m a n a n d H o w a r d W. J o n e s .
University of California San Francisco, Cancer Research Instituge, Hormone Receptor Laboratory, Department of Obstetrics and Gynecology
Introduetlon S t e r o i d h o r m o n e ~ e c e p t o r s a r e s o l u b l e c y t o p l a s m i c p r o t e i n s t h a t b i n d specific steriods with high affinity. The hormone-receptor complex can be translocated from the cytoplasm to t h e cell n u c l e u s w h e r e it i n t e r a c t s With c h r o m a t i n t o affect D N A t r a n s c r i p t i o n . I t-is virt u a l l y c e r t a i n t h a t a specific h o r m o n e c a n d i r e c t l y i n f l u e n c e t h e m e t a b o l i s m o f a cell or its g r o w t h o n l y if t h e cell h a s t h e r e c e p t o r for t h a t h o r m o n e . T h i s c o n c e p t i s so f u n d a m e n t a l t h a t i t is r e a s o n a b l e t o d e f i n e s t e r o i d h o r m o n e s b y t h e i r c a p a c i t y ' t o b i n d to a r e c e p t o r . T h u s , it~a m o l e c u l e Can b i n d to t h e a c t i v e site o f a n e s t r o g e n r e c e p t o r , it: is e i t h e r a n e s t r o g e n o r a n a n t i e s t r o g e n . . F u n c t i o n a l l y , a n e s t r o g e n is a m 0 1 e c u l e - r e c e p t o r c o m p l e x t h a t is c a p a b l e o f i n t e r a c t i n g a p p r o p r i a t e l y - w i t h n u c l e a r c h r o m a t i n to i n i t i a t e a series o f b i o c h e m i c a l e v e n t s t h a t will r e s u l t i n a m o r p h o l o g i c tissue c h a n g e . A n " e s t r o g e n i c " r e s p o n s e o c c u r s in t h e b r e a s t o r e n d o m e t r i M tissue o f m a r h m a l s e x p o s e d to estradiol, for example. A l t h o u g h s t e r o i d h o r m o n a l r e c e p t o r s h a v e b e e n a c t i v e l y s t u d i e d l n t h e l a b o r a t o r y for m a n y y e a r s ; o n l y r e c e n t l y ihave c o r r e l a t i o n s b e e n m a d e b e t w e e n in vitro d a t a a n d clinical responses to t h e r a p y : T h e w t l u e o f e s t r o g e n a n d p r o g e s t i n r e c e p t o r assays in t h e o v e r a l l m a n a g e m e n t o f p a t i e n t s w i t h b r e a s t c a r c i n o m a is n o w Clear W h e n c a r e f u l l y p e r f o r m e d , e s t r o g e n a n d p r o g e s t i n r e c e p t o r assays a r e o f u n e q u i v o c a l " v a l u e in s e l e c t i n g initial h o r m o n a l t h e r a p y for p a t i e n t s w i t h r e c u r r e n t : o r i n o P e r a b l e b r e a s t c a n c e r (25). A d d i t i o n ally, c o n v i n c i n g b u t as' y e t u n c o n f i r m e d e v i d e n c e exists d e m o n s t r a t i n g t h a t r e c e p t o r assays a r e i m p o r t a n t i n d e p e n d e n t f a c t o r s fo r p r e d i c t i n g risk o f r e c u r r e n c e in p a t i e n t s w i t h p m m a r y b r e a s t c a r c i n o m a s u n d e r g o i n g , d e f i n i t i v e s u r g e r y (39). A l t h o u g h c o n f l i c t i n g d a t a exist, : p r e l i m i n a r y e v i d e n c e suggests t h a t ~ e s t r o g e n receptor:i(ER)~ tigers m a y be predictive of the response of patients with advanced breast carcinoma to-multiagent c h e m o t h e r a p y as w e l f a s t o e n d o c r i n e t h e r a p y (18, 43). I t a p p e a r s t h a t , a t leastl for this * Reprint requests should be addressed to: Michael A. Friedman, M / D . , Cancer Research Institute-1282M, University of California, San Francisco, CA 94143 185 0305-7372/78/040 185 q- 10 $02.00/0
(~) 1978 Academic Press-Inc. (London)Ltd.
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l~I. A. FRIEDNIAN, P. G. HOFFI~IAN AND H. W. JONES
one type of adenocarcinoma, receptor studiesyield useful data not only about w h e t h e r the tumor, when advanced, will respond to hormonal manipulation, but also a b o u t its clinical aggressiveness. Therefore, it is v, orthwhile to consider whether hormone recepti~rs m a y be similarly indicative 'of the behavior of malignancies other t h a n breast cancer. Breast, endometrifim, a n d prostate are target tissues for the sex hormones a n d contain specific receptors for these hormones. I t is not surPr!sing t h a t some tumors arising from these tissuesalso cc,ntain receptors. However, the sex steroids directly affect a wide r a n g e of biologic p h e n o m e n a occurring in less obvious target tissues. Tlaus, renal function,skin pigmentation, h~ir growth, h e p a t i c protein synthesis, fat distribution, a n d bone m a t u r a tion are all modified b y sex steroids.-The presence of steriod hormone receptors is not restricted tO neoplasms arising in sex organs; they m a y be found in tumors arising from virtually a n y tissue. T h e following discussion will focus on ;five specific tumors. T w o of these t u m o r s ~ cancer of the prostate a n d u t e r u s ~ a r e often clearly u n d e r hormonal regulation. I n these, hormonal therapy represents a widely accepted m a i n s t a y o f clinical m a n a g e m e n t . T h r e e other neoplasms =cancer of (the kidney, melanoma, a n d ovarian c a n c e r ~ h a v e been reported to be influenced by sex hormones. For each of these tumors, a discussion o f data from animal a n d h u m a n studies concerning h o r m o n e dependence will a c c o m p a n y a review e,favailable information regarding the titers of E R a n d progesterone receptor (PR) in each case.
Prostate
ca~¢er
T h e prostate gland is dependent- on androgen stimulation for growth, function, a n d maintenance. T h e observation that testes are necessary for the m a i n t e n a n c e of the prostate in animals is over 300 years old (71). I n bulls a n d dogs orchiectomy results in prostatic atrophy.(28). I n castrated male dogs, testosterone stimulates a n d estrogen inhibits prostatic growth (29). Physiologically, secretion of prostatic fluid is enhanced by testosterone and diminished by estrogen (30). A p p a r e n t l y androgens ~re also required for the development of prostatic hyperplasia a n d carcinoma, since in spite of the high frequency of these diseases in the male population, no case of either has e v e n b e e n described in a h u m a n castrated before puberty (15). I n tissue culture; h u m a n prostatic cell growth is stimulated by androgens and inhibited b y estrogens (62). This in vitro inhibition shows t h a t estrogen influences prostatic growth not o n l y b y inhibiting pituitary, gonadotropin secretion but also b y a direct effect. It is well known t h a t a large n u m b e r of patients with advanced prostatic c a r c i n o m a benefit from orchiectomy or the administration of e x o g e n o u s estrogens. As p r i m a r y t h e r a p y , such manoeuvers yield over 50% Objective or clinically:useful subjective response-in i)atients with unreseetable or metastatic disease. Androgen receptors have-been u n e q u i v o c a l l y demonstrated in the rat prostate (46). Recept0~=for dihydrotestosterone ( D H T ) h a v e also been. convincingly d e m o n s t r a t e d in cytos01 from h y p e r t r o p h i c h u m a n prostatic-tissue, but in remarkably' few samples a n d only- b y t h e tedious ~a n d expensive techniques 0f:igradient centrifugation a n d electro: ph0resis " (22,~'27, 47, 54, 63). Tlae re~tson for the lack o f success w i t h m o r e clinicaIly applicable, simple r techniques has recently become clear.. I n h u m a n ~p-z'bstate there: is a h i g h c o n c e n t r a t i o n of a sex steroid binding globulin (SBG)'like protein, which binds D H T with high affinity i I n addition, throughout adult life ~ind even in extreme old age, circu-
HORMOtNE RECEPTOR. ASSAYS IN h~ALIGNANT DISEASE
187
Iating testosterone is present in high concentration. T h e prostate contains enough 5 0treductase to convert this testosterone to D H T in sufficient quantities to saturate the SBG. T h e high concentration of D H T also saturates the cytoplasmic androgen receptor, which is then almost totally translocated to the nucleus. In adult males, therefore, the cytoplasm contains only a small q u a n t i t y of occupied receptors a n d virtually no unoccupied receptors. This c o m b i n a t i o n of factors has thwarted attempts to correlate cytosol androgen receptor content w i t h response to endocrine therapy. Either no receptors have been found or SBG has been erroneously identified as the receptor. However, a recent p r e l i m i n a r y report by Mobbs et at/. klescrib~d a protamine sulfate precipitation assay for androgen receptor which reduces,the interference by SBG (56). In their series of 54 patients w i t h prostatic carcinoma, p a t i e n t s who h a d not received h o r m o n a l therapy showed uniformly low cytosol D H T receptor titers. I n treated patients who had lower plasma testosterone levels, receptor levels ranged w i d e l y from undetectable to 7000 sites/cell.: I n h y p o a n d r o g e n i c patients whose tissue samples were at least 6 0 % m a l i g n a n t (as opposed to those patients whose samples h a d p r e d o m i n a n t l y hypertrophic e l e m h n t s ) e l e v a t e d r e c e p t o r levels correlated with favorable response to endocrine therapy. A n even more promising approach has been described b~ M a n o n a al. U s i n g the synthetic androgen methyltrienolone ( R - 1 8 8 1 ) i n a n assay ffhich allowed R-1881 to exchang e with endogenous D H T , they convincingly demonstrated the presence of nuclear b u t not cytoplasmic androgen receptor in hyperplasdc h u m a n prostates (55), Additli~nally, c y t o p l a s m i c •but not nuclear progesterone receptor was demonstrated. W i t h t h e use of such techniques, a widely a p p l i c a b l e clinical assay foi" nuclear D H T receptors '~n prostatic carcinoma m a y soon be available.
Endornetr~al
cancer
M o s t endometrial adenocarcinomas probably.arise in hyperplastic endometrium (57). A continuous spectrum o f pathology exists beginning with simple glandular hyperplasia through adenomatous h y p e r p l a s i a a n d atyFiical hyperplasia, to carcinoma in situ, a n d ending with frankly invasive carcinoma. T h e de~(elopment of hyperplasia of the endom e t r i u m is-a predictable process which occurs with estrogen stimulation i n t h e absence of significant progesterone:. In simplistic terms, estrogens promote endometrial growth while progesterone, Which is secreted only in the last h a l f of~Tulatory cycles, causes t h e estrogen-Primed endornetrium to slow its growth a n d differentiate into a secretory tissue in which theferfilized ovum can be implanted. •It is the d y n a m i c balance:between these two hormones t h a t causes cyclical endometl'ial shedding, another process which helps to prevent hyperplasia. 2although ~hyperplasia i s u n c o m m o n and endometrial carcinoma: is r a r e in the premenopausal• population, both occur more frequently in anovulatory women. Those at increased risk include patients with polycystie-ovarian disease: (31, 51), w i t h estrogen secreting ovarian tumors (20), or with g o n a d a l dysgenesis (i:e., Turners' s y n d r o m e ) w h o a r e treatect with exogenous estrogens ( ! 1). I n theperi-menopausal period, w h e n significant ovarian estrogen production is present buto~iulati0n is ler.s frequent, a marked increase in the rate of e n d o m e t r i a I h y p e r p l a s i a atad carcinoma occurs. Administration Of moderate or high doses ofestrogen:to:peri=menopausal or p o s t - m e n o p a u s a l w o m e n has now been
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M.A. FRIEDMAN, P. G. HOFFMAN AND H. W. JONES
clearly shown to increase the risk of developing endometrial cancer (53). O v e r two,thirds of endometrial carcinomas, however, occur in post-menopausal women not taking estrogens (58). It is now recognized that the post-menopausal period is also associated with chronic unopposed estrogen exposure. Although the post-menopausal ovary produces virtually no estrog~.ns, the ovaries and the adrenal glands continue producing androgens, which are aromatized to estrogens in peripheral tissues such as fat a n d skin. Obesity tends to increase aromatization, liyer disease decreases the i n a c t i v a t i o n of estrogens, and both disorders are associated with an increased risk of endometrial carcinoma (38). T h a t progesdns appear to be clinically "antiestrogenic" wl'ien given to patients with hyperplasia a n d in some instances to patients w i t h adenocarcinoma of the endometrium can be partially accounted for by the modulation of E R a n d P R by progestins. Progestins do not bind to E R a n d hence a r e n o t truly antiestrogens (-as defined in the Introduction). However, the progestin-PR i n t e r a c t i o n markedly decreases the production of E R , thus decreasing the tissue's sensitivity to,estrogen (23, 45, 59, 72). Furthermore, the progestinP K interaction increases tenfold the activity of the enzym e :17-/~-hydroxysteroid dehydrogenase, which converts the potent estrogen estradiol to the less potent estrone (59, 66). T h u s progestins reduce thc-influence of estrogen in two ways: by directly reducing the a m o u n t of E R ; thus reducing tissue sensitivity to estrogen ;- a n d by reducing the intracellular concentration ofestradiol,-the most potent estrogen. Progestins, given exogenously to patients with endometrial hyperplasia, can cause a reversion to a normal histologic p a t t e r n (36, 37, 69):-!n patients w i t h recurrent or persistent adenomatous or: atypical hyperplasia who refuse surgical m a n a g e m e n t , progestin t h e r a p y can preventJthe development of malignancy. Left untreated, o v e r two-thi~ds of these patients ,,,could develop f r a n k adenocarcinoma (70). Currently, the preferred therapy for disseminated metastatic endometrial carcinoma, or for inoperable post-irradiation local disease, is progeatin therapy. Objective response m a y be expected in-30 to 4 0 % of patients (34, 48, 60, 61, 65), a n d occasional long term r e missions have been observed even in patients with progressive disease refi'actory tO irradiation a n d n o n h o r m o n a l chemotherapy. Clinically useful remissions are most freq u e n t l y seen in younger patients with well-differentiated tumo'urs a n d p u l m o n a r y metastases, a n d less frequently in those w i t h poorly differentiated lesions a n d pelvi~ o r a b d o m i n a l recurrencessoon after initial therapy (60, 6 I). T h e r e are, however, numerous exceptions to these rules (2). A p e r t i n e n t question is w h e t h e r t h e clinical use of receptor assays can improve the prediction ofresponse to progestinor other endocrine tllerapy-beyond t h a t achievedusing currently available indicators. E q u a l l y i m p o r t a n t is-whether response to non-endocrine c h e m o t h e r a p y can be predicted by receptor titers. These questions c a n n o t yet be.answered; A survey of the current knowledge o f r e c e p t o r s i n endometrium i n d i c a t e the problems, limitations, a n d promise-for the clinical u s e o f receptor assays in endometrial disease. Whereas n o r m a l breast tissue:has relatively :low-:E.R_and P R content, normal endom e t r i u m has high levels of these receptors (23, 45, 59, 7 2 ) . I n t h e progression from normal endometriurn through prOgressively severe hyperplasias, to weil-differentiated carcinomas a n d . a n a p i a s t i c lesions, most investigators have:f6und a steady decrease in P R content (45, 59, 72). Despite this general t r e n d , an occasional anaplastic lesion with high PP. v a l u e h a s b e e n reported, and in at least one series-ER titers were negatively correlated w i t h P R t i t e r s a n d increased in-less differentiated lesion s (21-), I f it is fG~ind t h a t receptor content simply reflects .morphologic differentiation, the test will be of-limited: value. O n e preliminary study suggests that progesterone receptor assays m a y be of value in predicting
HORMONE
R E C E P T O R ASSAYS I N M A L I G N A N T D I S E A S E
189
response to progestins in advanced disease. Ehrlich et al. reported that 3/3 patients with high P R responded to progestin therapy while only 1]10 with low, P R responded (14). W h e t h e r these results correlated with t u m o r differentiation was not reported.
R@I~LI c a n c e r
For well over 25 years, an a n i m a l m o d e l in which renal carcinoma-is s o m e w h a t comparabl e to that in h u m a n s has been studied; T h e male syrian hamster is sensitive to renal cancer induction by prolonged administration of estrogens (24, 35, 52). I n d u c t i o n of this t u m o r can be blocked by the simultaneous administration of testosterone or progesterone (24, 35). This t u m o r cannot be p r o d u c e d in female hamsters unless they have.undergone o o p h o r e c t o m y (35). I n transplanted or metastatic tumors, a variety of h o r m o n a l m a n l p u lations (such a s a d r e n a l e c t o m y o r progesterone therapy) can affect the growth of the t u m o r (4, 5). Li a n d associates measured t h e steroid h o r m o n e receptor content of four e n d o c r i n e - i n d u c e d h a m s t e r renal tumors. All of these had high titers-of E R and glucocorticoid recepiors, 3/4 had m o d e r a t e P R titers, a n d 2/4 h a d low, a n d r o g e n receptor titers (40-~42). D a t a exists supporting t h e h y p o t h e s i s that development of:renal a d e n o c a r c i n o m a in h u m a n s is als0 influenced by sex hormones. Frepubescent children have a very low incidence of t h e disease, a n d i n the a d u l t a 3 : 1 p r e p o n d e r a n c e of males : females with renal adenocarcinomas has been r e p o r t e d (6). For patients with disseminated renal cancer, t h e r a p y with p rogestational agents or androgens h a s b e e n advocated. Controversy exists as to the efticacy of such t r e a t m e n t ; objective response rates of b e t w e e n 0 a n d 30% have b e e n reported (6, 26), a n d the majority of responses occur in male patients with metastatic disease. T o date,- there have been few studies of h o r m o n e receptors in renal adenocarcinoma. G o l o m b a n d T h o m s e n described two r e n a l canCer specimens that lacked significant estradiol receptors (I 9). A series o f i 0 cases was reported by Conc01ino a n d associates ( l 0), who d e t e r m i n e d b o t h I~.R and PR. Five specimens h a d I~.R of 5.7 to 167 f m o l / m g protein (with a dissociation constant Ko o f 0.3 to 31 × 10-gM). Nine specimens h a d P R of 8 tO 196 fmo!/mg protein (with a K D of 0.47 to 64 x 10-gM) (10). The- presence o f P R i n 9 0 % o f the specimens assayed is discouraging in view of the m u c h smaller fracfion~of patients reported to ;espond to progestin therapy. However, the investigators g i v e data showing that o n l y one-fourth males a n d o n e - h a l f females had P R With a KD ofless than I 0-sM. Most investigators would consider this value a reasonable u p p e r limit for the KD o f P R : Concolino et al. treated 6 of the 10 patients with progestins, although w h e n their report was written, the t i m e o f foIIow-up wa s too brief to permit clinicaI correlations. I t is clear that further investigation o f P R in renal carcinoma must be done before a n e v a l u a t i o n of the c l i n i c a l worth Of receptor m e a s u r e m e n t i n this tumor is established.
iVJ[elano:mm T h e r e lisa teleost m o d e l system:in w h i c h sex hormones clearly affect the induction and p r o m 0 t i o n 0 f m a l i g n a n t m e l a n o m a s . : In-:the ~hybrid xiphophorus.species ofifish,~ the males s p o n t a n e o u s l y : d e v e l o p m e l a n o m a s fin their l a t e r a l chromophores w l t l a m u c h greater
190
h~. A. FRIEDMAN, P. G. HOFFI~IAN AND H. W. .JONES
frequency t h a n do the females, a n d the tumors do not arise until testicular function and androgen secretion begin. M a l i g n a n t pigmented lesions develop only in post-pubescent male fish (3, 64). Because h u m a n melanoma has a uniquely variable n a t u r a l history, its etiology has been subject of m u c h speculation. Some " l e g e n d s " suggest a strong influence of sex hormones, a n d some observations support this contention; I t is rare for m e l a n o m a to occur in the pre-pubescent child (8). W h e n noted in the pediatric population the tumors are usually associated with pre-existing pigmented lesions (such as giant nevi). T h e growth of melanomas has been reported to both regress a n d progress rapidly d u r i n g p r e g n a n c y (a state characterized b y exuberant hormonal excesses). T h a t a tumor m i g h t grow rapidly d u r i n g pregnancy can be easily explained: p r e g n a n c y is a relatively i m m u n o suppressed state and p r e g n a n t women are at an increased risk for a numbet~ of hazards including tuberculosis and fungal infections. T h e r e also have been a thw well'documented regressions of m~lanoma ~gsociated with t h e termination of p r e g n a n c y ; and conversely, melanomas have been reported to regress during p r e g n a n c y (1, 9). I n a disease notorious for its protean natural history, however, considerable restraint must be exercised in interpreting these da~a. Overalli Women with m e l a n o m a have a b e t t e r prognosis t h a n m e n irrespective of stage or site of disease a n d type of treatment received. W o m e n respond tO chemotherapy more often, more completely, a n d more dtirably (7, 12). Patients with disseminated m e l a n o m a also occasionally respond to hormonal therapy: In-a study b y J o h n s o n el aI., 11 ~o of patients had a n objective partial response to therapy with 6 0t-methyl preg-4-ene-3,11,20-trione (a d r u g with antiestrogenic a n d weak g l u c o corticoid properties) (32). Mor e recently, F i s h e r et al. studied 18 male a n d post-menopausal female patients with disseminated melanoma refractory to D T I C or m e t h y l C C N U . T h e y were treated w i t h diethylstilbestrol (DES) ( I S - r a g / d a y ) ; 2 patients (11 ~/o) h a d an objectivepartiai response and m i n i m a l toxicity was noted (17). Didolkar a n d coworkers (13) evaluated 90 patients with m e l a n o m a who h a d previously received D T I C or methyl C C N U . These patients received 15 mg/kg/day of estramustine phosphate ( E s t r a c y t - estradiol linked to nitroge n mustard). Four patients (3[7 women and 1/13 m e n ) e x perienced a n objective response a n d o n e complete response was noted. Nausea, vomiting, a n d fluid retention were the most serious side effects noted (13). T o date, only two studies by Fisher a n d his group have reported the incidence of El~ or P R i n m e l a n o m a tissue (16). In their first series 16[35 specimens were considered E R positive. These receptors were evenly distributed between male a n d female patients. I n their additional experience (17) 4[18 specimens were positive for E R , 3[6 for p R , 1/15 for androgen receptors, 4/12 for glucocorticoid receptor.-The published data in both of these preliminary reports were insufficient to j u d g e the quality of the receptor assays. Since Fisher found t h a t the two patients with partial responses to D E S w e r e estrogen receptor negative and P R w ~ not measured (17), the clinical value of receptor measurements i n m e l a n o m a remains completely unsubstantiated.
Ovari_" ~ n c a n c e r
T h e o v a r y is not o:fly the most obvious source o f e s t r o g e n s a n d Progestins b u t also a target organ for these h o r m o n e s and for androgens a s well. S o m e ovarian epithelial
H O R M O N E R E C E P T O R ASSAYS IN MALIGNANT DISEASE
191
turnouts are likely to c o n t a i n ste:~roid receptors. Unfortunately, very little has been reported on receptorsln either benign or malignant ovarian tumours. Estrogen receptors were n o t e d in one ovarian cancer specimen by Gollomb a n d T h o m s e n but they found no E K i n 3 n o r m a l ovaries (19). Young et al. described P R in 2 ovarian tumors (I 3 a n d 49 fmol/mg protein) (72)' Interest in the further evaluation of receptors h a s been piqued by reports of the efficacy of h o r m o n a l therapy in some patients with disseminated ovarian cancer. These data are summarized in T a b l e 1. Interpretation is difficult since the definition of Objective r e : sponses, the type of patient p o p u ~ t i o n , the h o r m o n e used, and the schedule of treatment differ significantly. No specific histo!ogic subtype, site or disease, or patient characteristic l~as been identified as a useful prognosticFactor for predicting response. Nevertheless, in this compilation !8/76 ( 2 4 % ) o f patients benefited objectively from this form ofendocrine therapy, which u s u a l l y w a s administered after the failure of conventional chemotherapeutic, surgical, or radiation therapy. Table
I. Horn~onal thersepy o f o v a r i a n
Investig'ator L o n g (44) ~ r a r d (68) Malkasian (49) Malkaaian (50) Jolles (33) Vama (67)
cancer
Agent Diethylstilbestrol |7 0t~Hydroxy-19-norprogcsterone 6-Dehydro-6, 1?-~t-diifi%thyl progesterone Medroxyprogestero//e acerbate 17'0t-HydroXyprogester0ne~ 17-n°caproat¢ ! 7-ct-Hydroxyprogestcrone17.n,~ap/'oate "
Number of patients
Partial rc.pome,
9 23 9
2 9 2
19 10
I ~
6
l
76
18
(24%)
COnclusions E x t e n s i v e b a s i c and clinical investigation-is continuing in an effort to define hormone fee:eptor distribution and clinical relevance in m a n y neoplasms. Some endometrial carcinomas ` c o n t a i n measurable ER: a n d PR, and some prostatic carcinomas contain a n d r o g e n receptors. I t is probable that some malignant melanomas, renal carcinomas a n d o v a r i a n c a r c i n o m a s also c o n t a i n E R o r P R o r both. Clinical correlation between receptor tilers and response to therapy is dtilI eitheria:ck~ng or tenuous for all these tt, mors, a n d it wouid be premature to base therapy for these tumors on receptor d a t a except i n clinical investigations. T h e receptor d a t a that is b e i n g r e p o r t e d shouId be approached criticallyt~by the i n d i v i d u a l reader with the caveat that initial lpublications are usually more optiiniStic daa~x final definitive facts. TO be c 0 n v i n c i n g a n : i n v e s t i g a t i 0 n should prove that wlmt is beingmeasurediS a c t u a l l y r e c e p t o r and that the receptor is in the tumori noi in-adjacent non-neoplastic dssue: Specifically, these questions should be considered by the reader. I. Has care been taken: to eliminate measurement of c o n t a m i n a t i n g se~Cumproteins which also bind the ligand (hormone) whose receptor is being measured ?
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M. A. FRIEDMAN, P. G. H O F F M A N AND H. W. J O N E S
2. I f a synthetic ligand is used, is the !igand specific for the receptor which is purported to be measured ? (SR-1881 binds avidly to both androgen and progesterone red,eptors; R-5020 binds.slightly to cortisol receptors a s well as to progesterone receptors). 3. Is adequate care taken to characterize the binding protein as receptor ? Thiscould be accomplished either by measuring its affinity for ligandor by characterizing its unique mobilitypattern (e.g., in a sucrose gradient;-in an electrophoretic field, or by using 'isoelectric focusing procedures) . 4. Is there adequate assurance that tumor tissue; rather than surrounding normal or hyperplastic tissue, contains the receptor that :is being measured ? T h i s point is espe6iM1g~critical i n assessing results Of primary endometrial and prostatic tumor studies, sincel tissue adjacent to t h e tumor may contain more receptor than the tumor itself. 5. When receptor assays are reported to be_negative, what: is the ttireshold of the analytic techn!que being u s e d ? W h e n reported as positive, is there assurance that the result is significantly different :from zero ? Are the criteria for positivity and negativity explained satisfactorily ? 6, Ih comparing receptor titers in tumors from diiTerent individuals, a r e the differences in endogenous hormones taken into account ? We have stressed the preliminary nature of the current data concerning receptors in tumors o~her than breast cancer. ~or the tumors discussed here, improved technology for relia.ble measurement of receptors is sorely nebded, iWell:designed clinical studies :indicating the relative influence of receptor titers on results ofendocrine and non-endocrine therapy a r e required in order tb--apply receptor m e a s u r e m e n ~ rationally in clinical management. Receptors m a y also b e indicat0rs ofprognosisirrespectiye of the therapy used. Will receptor measurements improvelselection of therapy or simply predict which patients are likel~ to sum,ive longer independent of therapy ? Both possibilities are equaily plausible at present. With So manyquesti0ns a s y e t unanswered;obvi0uSly t h e investigation of hormone receptors i n malignantr disease~Wiii continue:to bc one of the mbst vigorously pursued areasi;o-f onco!ogic research.
References
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AND
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56. Mobbs, B. G., Johnson, I. E., & Connolly,J. G. (1978) PFoc.Am. Assoc. Cancer Res. 19" 801. 57. Novack, E. R., Jones, G. S. & J'oncs,H. W. (1975) Novak's Textbook of Gynecology p. 346 Baltimorc: Williams and Wilkins. 58. Novack, E. R., Jones, G. S. & Jones, H. W. (1975) Novak's Textbook ofGynetologg p. 350. Bahimore: Williams and Wilkim. 59. Pollow, K., Schm~k-Gollwitzcr, M. & Nevlnny-Stlckcl,J, (1977) In W. L. McGuirc, J, P. Raymond & F. E. Baullcu (Eds), ProgesteroneReceptorsin Normal and Neoplasti¢.Tissr~r, p. 313. New York: Raven Press. 60. Reifenstein,E. C. (1971) Cancer 27: 485. 61. Reifcnstein, E. C~. (1974) Gyntcologi¢ Oncol. 2: 377. 62. Rochl, L. (1958) Br. 3". Urol. 30: 450. 63. Roscn; V.,Jung, I., Baulleu, F. E. & Robcl, P. (1975) or. Clin. Endocr. Metab. 41: 761. 64. Sicilalno, M.J., Perlmutte, A. &Clark, E. (197i)Cancer R~. $1: 725. 65, Smith, J. P, (1969) Cancerof the Uterg~and Ovary, p. 73. Chicago: Year Book Publlsh~rs. 66. Tseng, L. & Gurplde, E. (1974) Et~Iocrinolog9941:419. 67. Varga, A, & Henrikscn, E, (1962) Obstet. Gyne¢, 16."209. 68. Ward, H. W. C. (1972) J. Obstet. Gynec. Br. Commonw. 795 555. 69. Wentz, W. B' (1964) Obstet. Gyr~¢. 24: 370. 70. Wcntz, W. B. (1974) Gyntc. OncoL2: 354. 71. Whitterldgc, G, (1964) The Anatomical Lectarts of WilliamHarvey. London: Livingstoncs with the Royal College of Physicians. 72. Young, P. C. M. & Cleary, R. E. (1974) Y. Clin. Erdoer, Metab. 42:667.
T h e d i n i c a l v a l u e o f h o r m o n e r e c e p t o r a s s a y s in malignant disease M i c h a e l A. F r i e d m a n , * p h i l i p G. I ~ o f F m a n a n d H o w a r d W. J o n e s .
University of California San Francisco, Cancer Research Instituge, Hormone Receptor Laboratory, Department of Obstetrics and Gynecology
Introduetlon S t e r o i d h o r m o n e ~ e c e p t o r s a r e s o l u b l e c y t o p l a s m i c p r o t e i n s t h a t b i n d specific steriods with high affinity. The hormone-receptor complex can be translocated from the cytoplasm to t h e cell n u c l e u s w h e r e it i n t e r a c t s With c h r o m a t i n t o affect D N A t r a n s c r i p t i o n . I t-is virt u a l l y c e r t a i n t h a t a specific h o r m o n e c a n d i r e c t l y i n f l u e n c e t h e m e t a b o l i s m o f a cell or its g r o w t h o n l y if t h e cell h a s t h e r e c e p t o r for t h a t h o r m o n e . T h i s c o n c e p t i s so f u n d a m e n t a l t h a t i t is r e a s o n a b l e t o d e f i n e s t e r o i d h o r m o n e s b y t h e i r c a p a c i t y ' t o b i n d to a r e c e p t o r . T h u s , it~a m o l e c u l e Can b i n d to t h e a c t i v e site o f a n e s t r o g e n r e c e p t o r , it: is e i t h e r a n e s t r o g e n o r a n a n t i e s t r o g e n . . F u n c t i o n a l l y , a n e s t r o g e n is a m 0 1 e c u l e - r e c e p t o r c o m p l e x t h a t is c a p a b l e o f i n t e r a c t i n g a p p r o p r i a t e l y - w i t h n u c l e a r c h r o m a t i n to i n i t i a t e a series o f b i o c h e m i c a l e v e n t s t h a t will r e s u l t i n a m o r p h o l o g i c tissue c h a n g e . A n " e s t r o g e n i c " r e s p o n s e o c c u r s in t h e b r e a s t o r e n d o m e t r i M tissue o f m a r h m a l s e x p o s e d to estradiol, for example. A l t h o u g h s t e r o i d h o r m o n a l r e c e p t o r s h a v e b e e n a c t i v e l y s t u d i e d l n t h e l a b o r a t o r y for m a n y y e a r s ; o n l y r e c e n t l y ihave c o r r e l a t i o n s b e e n m a d e b e t w e e n in vitro d a t a a n d clinical responses to t h e r a p y : T h e w t l u e o f e s t r o g e n a n d p r o g e s t i n r e c e p t o r assays in t h e o v e r a l l m a n a g e m e n t o f p a t i e n t s w i t h b r e a s t c a r c i n o m a is n o w Clear W h e n c a r e f u l l y p e r f o r m e d , e s t r o g e n a n d p r o g e s t i n r e c e p t o r assays a r e o f u n e q u i v o c a l " v a l u e in s e l e c t i n g initial h o r m o n a l t h e r a p y for p a t i e n t s w i t h r e c u r r e n t : o r i n o P e r a b l e b r e a s t c a n c e r (25). A d d i t i o n ally, c o n v i n c i n g b u t as' y e t u n c o n f i r m e d e v i d e n c e exists d e m o n s t r a t i n g t h a t r e c e p t o r assays a r e i m p o r t a n t i n d e p e n d e n t f a c t o r s fo r p r e d i c t i n g risk o f r e c u r r e n c e in p a t i e n t s w i t h p m m a r y b r e a s t c a r c i n o m a s u n d e r g o i n g , d e f i n i t i v e s u r g e r y (39). A l t h o u g h c o n f l i c t i n g d a t a exist, : p r e l i m i n a r y e v i d e n c e suggests t h a t ~ e s t r o g e n receptor:i(ER)~ tigers m a y be predictive of the response of patients with advanced breast carcinoma to-multiagent c h e m o t h e r a p y as w e l f a s t o e n d o c r i n e t h e r a p y (18, 43). I t a p p e a r s t h a t , a t leastl for this * Reprint requests should be addressed to: Michael A. Friedman, M / D . , Cancer Research Institute-1282M, University of California, San Francisco, CA 94143 185 0305-7372/78/040 185 q- 10 $02.00/0
(~) 1978 Academic Press-Inc. (London)Ltd.
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one type of adenocarcinoma, receptor studiesyield useful data not only about w h e t h e r the tumor, when advanced, will respond to hormonal manipulation, but also a b o u t its clinical aggressiveness. Therefore, it is v, orthwhile to consider whether hormone recepti~rs m a y be similarly indicative 'of the behavior of malignancies other t h a n breast cancer. Breast, endometrifim, a n d prostate are target tissues for the sex hormones a n d contain specific receptors for these hormones. I t is not surPr!sing t h a t some tumors arising from these tissuesalso cc,ntain receptors. However, the sex steroids directly affect a wide r a n g e of biologic p h e n o m e n a occurring in less obvious target tissues. Tlaus, renal function,skin pigmentation, h~ir growth, h e p a t i c protein synthesis, fat distribution, a n d bone m a t u r a tion are all modified b y sex steroids.-The presence of steriod hormone receptors is not restricted tO neoplasms arising in sex organs; they m a y be found in tumors arising from virtually a n y tissue. T h e following discussion will focus on ;five specific tumors. T w o of these t u m o r s ~ cancer of the prostate a n d u t e r u s ~ a r e often clearly u n d e r hormonal regulation. I n these, hormonal therapy represents a widely accepted m a i n s t a y o f clinical m a n a g e m e n t . T h r e e other neoplasms =cancer of (the kidney, melanoma, a n d ovarian c a n c e r ~ h a v e been reported to be influenced by sex hormones. For each of these tumors, a discussion o f data from animal a n d h u m a n studies concerning h o r m o n e dependence will a c c o m p a n y a review e,favailable information regarding the titers of E R a n d progesterone receptor (PR) in each case.
Prostate
ca~¢er
T h e prostate gland is dependent- on androgen stimulation for growth, function, a n d maintenance. T h e observation that testes are necessary for the m a i n t e n a n c e of the prostate in animals is over 300 years old (71). I n bulls a n d dogs orchiectomy results in prostatic atrophy.(28). I n castrated male dogs, testosterone stimulates a n d estrogen inhibits prostatic growth (29). Physiologically, secretion of prostatic fluid is enhanced by testosterone and diminished by estrogen (30). A p p a r e n t l y androgens ~re also required for the development of prostatic hyperplasia a n d carcinoma, since in spite of the high frequency of these diseases in the male population, no case of either has e v e n b e e n described in a h u m a n castrated before puberty (15). I n tissue culture; h u m a n prostatic cell growth is stimulated by androgens and inhibited b y estrogens (62). This in vitro inhibition shows t h a t estrogen influences prostatic growth not o n l y b y inhibiting pituitary, gonadotropin secretion but also b y a direct effect. It is well known t h a t a large n u m b e r of patients with advanced prostatic c a r c i n o m a benefit from orchiectomy or the administration of e x o g e n o u s estrogens. As p r i m a r y t h e r a p y , such manoeuvers yield over 50% Objective or clinically:useful subjective response-in i)atients with unreseetable or metastatic disease. Androgen receptors have-been u n e q u i v o c a l l y demonstrated in the rat prostate (46). Recept0~=for dihydrotestosterone ( D H T ) h a v e also been. convincingly d e m o n s t r a t e d in cytos01 from h y p e r t r o p h i c h u m a n prostatic-tissue, but in remarkably' few samples a n d only- b y t h e tedious ~a n d expensive techniques 0f:igradient centrifugation a n d electro: ph0resis " (22,~'27, 47, 54, 63). Tlae re~tson for the lack o f success w i t h m o r e clinicaIly applicable, simple r techniques has recently become clear.. I n h u m a n ~p-z'bstate there: is a h i g h c o n c e n t r a t i o n of a sex steroid binding globulin (SBG)'like protein, which binds D H T with high affinity i I n addition, throughout adult life ~ind even in extreme old age, circu-
HORMOtNE RECEPTOR. ASSAYS IN h~ALIGNANT DISEASE
187
Iating testosterone is present in high concentration. T h e prostate contains enough 5 0treductase to convert this testosterone to D H T in sufficient quantities to saturate the SBG. T h e high concentration of D H T also saturates the cytoplasmic androgen receptor, which is then almost totally translocated to the nucleus. In adult males, therefore, the cytoplasm contains only a small q u a n t i t y of occupied receptors a n d virtually no unoccupied receptors. This c o m b i n a t i o n of factors has thwarted attempts to correlate cytosol androgen receptor content w i t h response to endocrine therapy. Either no receptors have been found or SBG has been erroneously identified as the receptor. However, a recent p r e l i m i n a r y report by Mobbs et at/. klescrib~d a protamine sulfate precipitation assay for androgen receptor which reduces,the interference by SBG (56). In their series of 54 patients w i t h prostatic carcinoma, p a t i e n t s who h a d not received h o r m o n a l therapy showed uniformly low cytosol D H T receptor titers. I n treated patients who had lower plasma testosterone levels, receptor levels ranged w i d e l y from undetectable to 7000 sites/cell.: I n h y p o a n d r o g e n i c patients whose tissue samples were at least 6 0 % m a l i g n a n t (as opposed to those patients whose samples h a d p r e d o m i n a n t l y hypertrophic e l e m h n t s ) e l e v a t e d r e c e p t o r levels correlated with favorable response to endocrine therapy. A n even more promising approach has been described b~ M a n o n a al. U s i n g the synthetic androgen methyltrienolone ( R - 1 8 8 1 ) i n a n assay ffhich allowed R-1881 to exchang e with endogenous D H T , they convincingly demonstrated the presence of nuclear b u t not cytoplasmic androgen receptor in hyperplasdc h u m a n prostates (55), Additli~nally, c y t o p l a s m i c •but not nuclear progesterone receptor was demonstrated. W i t h t h e use of such techniques, a widely a p p l i c a b l e clinical assay foi" nuclear D H T receptors '~n prostatic carcinoma m a y soon be available.
Endornetr~al
cancer
M o s t endometrial adenocarcinomas probably.arise in hyperplastic endometrium (57). A continuous spectrum o f pathology exists beginning with simple glandular hyperplasia through adenomatous h y p e r p l a s i a a n d atyFiical hyperplasia, to carcinoma in situ, a n d ending with frankly invasive carcinoma. T h e de~(elopment of hyperplasia of the endom e t r i u m is-a predictable process which occurs with estrogen stimulation i n t h e absence of significant progesterone:. In simplistic terms, estrogens promote endometrial growth while progesterone, Which is secreted only in the last h a l f of~Tulatory cycles, causes t h e estrogen-Primed endornetrium to slow its growth a n d differentiate into a secretory tissue in which theferfilized ovum can be implanted. •It is the d y n a m i c balance:between these two hormones t h a t causes cyclical endometl'ial shedding, another process which helps to prevent hyperplasia. 2although ~hyperplasia i s u n c o m m o n and endometrial carcinoma: is r a r e in the premenopausal• population, both occur more frequently in anovulatory women. Those at increased risk include patients with polycystie-ovarian disease: (31, 51), w i t h estrogen secreting ovarian tumors (20), or with g o n a d a l dysgenesis (i:e., Turners' s y n d r o m e ) w h o a r e treatect with exogenous estrogens ( ! 1). I n theperi-menopausal period, w h e n significant ovarian estrogen production is present buto~iulati0n is ler.s frequent, a marked increase in the rate of e n d o m e t r i a I h y p e r p l a s i a atad carcinoma occurs. Administration Of moderate or high doses ofestrogen:to:peri=menopausal or p o s t - m e n o p a u s a l w o m e n has now been
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M.A. FRIEDMAN, P. G. HOFFMAN AND H. W. JONES
clearly shown to increase the risk of developing endometrial cancer (53). O v e r two,thirds of endometrial carcinomas, however, occur in post-menopausal women not taking estrogens (58). It is now recognized that the post-menopausal period is also associated with chronic unopposed estrogen exposure. Although the post-menopausal ovary produces virtually no estrog~.ns, the ovaries and the adrenal glands continue producing androgens, which are aromatized to estrogens in peripheral tissues such as fat a n d skin. Obesity tends to increase aromatization, liyer disease decreases the i n a c t i v a t i o n of estrogens, and both disorders are associated with an increased risk of endometrial carcinoma (38). T h a t progesdns appear to be clinically "antiestrogenic" wl'ien given to patients with hyperplasia a n d in some instances to patients w i t h adenocarcinoma of the endometrium can be partially accounted for by the modulation of E R a n d P R by progestins. Progestins do not bind to E R a n d hence a r e n o t truly antiestrogens (-as defined in the Introduction). However, the progestin-PR i n t e r a c t i o n markedly decreases the production of E R , thus decreasing the tissue's sensitivity to,estrogen (23, 45, 59, 72). Furthermore, the progestinP K interaction increases tenfold the activity of the enzym e :17-/~-hydroxysteroid dehydrogenase, which converts the potent estrogen estradiol to the less potent estrone (59, 66). T h u s progestins reduce thc-influence of estrogen in two ways: by directly reducing the a m o u n t of E R ; thus reducing tissue sensitivity to estrogen ;- a n d by reducing the intracellular concentration ofestradiol,-the most potent estrogen. Progestins, given exogenously to patients with endometrial hyperplasia, can cause a reversion to a normal histologic p a t t e r n (36, 37, 69):-!n patients w i t h recurrent or persistent adenomatous or: atypical hyperplasia who refuse surgical m a n a g e m e n t , progestin t h e r a p y can preventJthe development of malignancy. Left untreated, o v e r two-thi~ds of these patients ,,,could develop f r a n k adenocarcinoma (70). Currently, the preferred therapy for disseminated metastatic endometrial carcinoma, or for inoperable post-irradiation local disease, is progeatin therapy. Objective response m a y be expected in-30 to 4 0 % of patients (34, 48, 60, 61, 65), a n d occasional long term r e missions have been observed even in patients with progressive disease refi'actory tO irradiation a n d n o n h o r m o n a l chemotherapy. Clinically useful remissions are most freq u e n t l y seen in younger patients with well-differentiated tumo'urs a n d p u l m o n a r y metastases, a n d less frequently in those w i t h poorly differentiated lesions a n d pelvi~ o r a b d o m i n a l recurrencessoon after initial therapy (60, 6 I). T h e r e are, however, numerous exceptions to these rules (2). A p e r t i n e n t question is w h e t h e r t h e clinical use of receptor assays can improve the prediction ofresponse to progestinor other endocrine tllerapy-beyond t h a t achievedusing currently available indicators. E q u a l l y i m p o r t a n t is-whether response to non-endocrine c h e m o t h e r a p y can be predicted by receptor titers. These questions c a n n o t yet be.answered; A survey of the current knowledge o f r e c e p t o r s i n endometrium i n d i c a t e the problems, limitations, a n d promise-for the clinical u s e o f receptor assays in endometrial disease. Whereas n o r m a l breast tissue:has relatively :low-:E.R_and P R content, normal endom e t r i u m has high levels of these receptors (23, 45, 59, 7 2 ) . I n t h e progression from normal endometriurn through prOgressively severe hyperplasias, to weil-differentiated carcinomas a n d . a n a p i a s t i c lesions, most investigators have:f6und a steady decrease in P R content (45, 59, 72). Despite this general t r e n d , an occasional anaplastic lesion with high PP. v a l u e h a s b e e n reported, and in at least one series-ER titers were negatively correlated w i t h P R t i t e r s a n d increased in-less differentiated lesion s (21-), I f it is fG~ind t h a t receptor content simply reflects .morphologic differentiation, the test will be of-limited: value. O n e preliminary study suggests that progesterone receptor assays m a y be of value in predicting
HORMONE
R E C E P T O R ASSAYS I N M A L I G N A N T D I S E A S E
189
response to progestins in advanced disease. Ehrlich et al. reported that 3/3 patients with high P R responded to progestin therapy while only 1]10 with low, P R responded (14). W h e t h e r these results correlated with t u m o r differentiation was not reported.
R@I~LI c a n c e r
For well over 25 years, an a n i m a l m o d e l in which renal carcinoma-is s o m e w h a t comparabl e to that in h u m a n s has been studied; T h e male syrian hamster is sensitive to renal cancer induction by prolonged administration of estrogens (24, 35, 52). I n d u c t i o n of this t u m o r can be blocked by the simultaneous administration of testosterone or progesterone (24, 35). This t u m o r cannot be p r o d u c e d in female hamsters unless they have.undergone o o p h o r e c t o m y (35). I n transplanted or metastatic tumors, a variety of h o r m o n a l m a n l p u lations (such a s a d r e n a l e c t o m y o r progesterone therapy) can affect the growth of the t u m o r (4, 5). Li a n d associates measured t h e steroid h o r m o n e receptor content of four e n d o c r i n e - i n d u c e d h a m s t e r renal tumors. All of these had high titers-of E R and glucocorticoid recepiors, 3/4 had m o d e r a t e P R titers, a n d 2/4 h a d low, a n d r o g e n receptor titers (40-~42). D a t a exists supporting t h e h y p o t h e s i s that development of:renal a d e n o c a r c i n o m a in h u m a n s is als0 influenced by sex hormones. Frepubescent children have a very low incidence of t h e disease, a n d i n the a d u l t a 3 : 1 p r e p o n d e r a n c e of males : females with renal adenocarcinomas has been r e p o r t e d (6). For patients with disseminated renal cancer, t h e r a p y with p rogestational agents or androgens h a s b e e n advocated. Controversy exists as to the efticacy of such t r e a t m e n t ; objective response rates of b e t w e e n 0 a n d 30% have b e e n reported (6, 26), a n d the majority of responses occur in male patients with metastatic disease. T o date,- there have been few studies of h o r m o n e receptors in renal adenocarcinoma. G o l o m b a n d T h o m s e n described two r e n a l canCer specimens that lacked significant estradiol receptors (I 9). A series o f i 0 cases was reported by Conc01ino a n d associates ( l 0), who d e t e r m i n e d b o t h I~.R and PR. Five specimens h a d I~.R of 5.7 to 167 f m o l / m g protein (with a dissociation constant Ko o f 0.3 to 31 × 10-gM). Nine specimens h a d P R of 8 tO 196 fmo!/mg protein (with a K D of 0.47 to 64 x 10-gM) (10). The- presence o f P R i n 9 0 % o f the specimens assayed is discouraging in view of the m u c h smaller fracfion~of patients reported to ;espond to progestin therapy. However, the investigators g i v e data showing that o n l y one-fourth males a n d o n e - h a l f females had P R With a KD ofless than I 0-sM. Most investigators would consider this value a reasonable u p p e r limit for the KD o f P R : Concolino et al. treated 6 of the 10 patients with progestins, although w h e n their report was written, the t i m e o f foIIow-up wa s too brief to permit clinicaI correlations. I t is clear that further investigation o f P R in renal carcinoma must be done before a n e v a l u a t i o n of the c l i n i c a l worth Of receptor m e a s u r e m e n t i n this tumor is established.
iVJ[elano:mm T h e r e lisa teleost m o d e l system:in w h i c h sex hormones clearly affect the induction and p r o m 0 t i o n 0 f m a l i g n a n t m e l a n o m a s . : In-:the ~hybrid xiphophorus.species ofifish,~ the males s p o n t a n e o u s l y : d e v e l o p m e l a n o m a s fin their l a t e r a l chromophores w l t l a m u c h greater
190
h~. A. FRIEDMAN, P. G. HOFFI~IAN AND H. W. .JONES
frequency t h a n do the females, a n d the tumors do not arise until testicular function and androgen secretion begin. M a l i g n a n t pigmented lesions develop only in post-pubescent male fish (3, 64). Because h u m a n melanoma has a uniquely variable n a t u r a l history, its etiology has been subject of m u c h speculation. Some " l e g e n d s " suggest a strong influence of sex hormones, a n d some observations support this contention; I t is rare for m e l a n o m a to occur in the pre-pubescent child (8). W h e n noted in the pediatric population the tumors are usually associated with pre-existing pigmented lesions (such as giant nevi). T h e growth of melanomas has been reported to both regress a n d progress rapidly d u r i n g p r e g n a n c y (a state characterized b y exuberant hormonal excesses). T h a t a tumor m i g h t grow rapidly d u r i n g pregnancy can be easily explained: p r e g n a n c y is a relatively i m m u n o suppressed state and p r e g n a n t women are at an increased risk for a numbet~ of hazards including tuberculosis and fungal infections. T h e r e also have been a thw well'documented regressions of m~lanoma ~gsociated with t h e termination of p r e g n a n c y ; and conversely, melanomas have been reported to regress during p r e g n a n c y (1, 9). I n a disease notorious for its protean natural history, however, considerable restraint must be exercised in interpreting these da~a. Overalli Women with m e l a n o m a have a b e t t e r prognosis t h a n m e n irrespective of stage or site of disease a n d type of treatment received. W o m e n respond tO chemotherapy more often, more completely, a n d more dtirably (7, 12). Patients with disseminated m e l a n o m a also occasionally respond to hormonal therapy: In-a study b y J o h n s o n el aI., 11 ~o of patients had a n objective partial response to therapy with 6 0t-methyl preg-4-ene-3,11,20-trione (a d r u g with antiestrogenic a n d weak g l u c o corticoid properties) (32). Mor e recently, F i s h e r et al. studied 18 male a n d post-menopausal female patients with disseminated melanoma refractory to D T I C or m e t h y l C C N U . T h e y were treated w i t h diethylstilbestrol (DES) ( I S - r a g / d a y ) ; 2 patients (11 ~/o) h a d an objectivepartiai response and m i n i m a l toxicity was noted (17). Didolkar a n d coworkers (13) evaluated 90 patients with m e l a n o m a who h a d previously received D T I C or methyl C C N U . These patients received 15 mg/kg/day of estramustine phosphate ( E s t r a c y t - estradiol linked to nitroge n mustard). Four patients (3[7 women and 1/13 m e n ) e x perienced a n objective response a n d o n e complete response was noted. Nausea, vomiting, a n d fluid retention were the most serious side effects noted (13). T o date, only two studies by Fisher a n d his group have reported the incidence of El~ or P R i n m e l a n o m a tissue (16). In their first series 16[35 specimens were considered E R positive. These receptors were evenly distributed between male a n d female patients. I n their additional experience (17) 4[18 specimens were positive for E R , 3[6 for p R , 1/15 for androgen receptors, 4/12 for glucocorticoid receptor.-The published data in both of these preliminary reports were insufficient to j u d g e the quality of the receptor assays. Since Fisher found t h a t the two patients with partial responses to D E S w e r e estrogen receptor negative and P R w ~ not measured (17), the clinical value of receptor measurements i n m e l a n o m a remains completely unsubstantiated.
Ovari_" ~ n c a n c e r
T h e o v a r y is not o:fly the most obvious source o f e s t r o g e n s a n d Progestins b u t also a target organ for these h o r m o n e s and for androgens a s well. S o m e ovarian epithelial
H O R M O N E R E C E P T O R ASSAYS IN MALIGNANT DISEASE
191
turnouts are likely to c o n t a i n ste:~roid receptors. Unfortunately, very little has been reported on receptorsln either benign or malignant ovarian tumours. Estrogen receptors were n o t e d in one ovarian cancer specimen by Gollomb a n d T h o m s e n but they found no E K i n 3 n o r m a l ovaries (19). Young et al. described P R in 2 ovarian tumors (I 3 a n d 49 fmol/mg protein) (72)' Interest in the further evaluation of receptors h a s been piqued by reports of the efficacy of h o r m o n a l therapy in some patients with disseminated ovarian cancer. These data are summarized in T a b l e 1. Interpretation is difficult since the definition of Objective r e : sponses, the type of patient p o p u ~ t i o n , the h o r m o n e used, and the schedule of treatment differ significantly. No specific histo!ogic subtype, site or disease, or patient characteristic l~as been identified as a useful prognosticFactor for predicting response. Nevertheless, in this compilation !8/76 ( 2 4 % ) o f patients benefited objectively from this form ofendocrine therapy, which u s u a l l y w a s administered after the failure of conventional chemotherapeutic, surgical, or radiation therapy. Table
I. Horn~onal thersepy o f o v a r i a n
Investig'ator L o n g (44) ~ r a r d (68) Malkasian (49) Malkaaian (50) Jolles (33) Vama (67)
cancer
Agent Diethylstilbestrol |7 0t~Hydroxy-19-norprogcsterone 6-Dehydro-6, 1?-~t-diifi%thyl progesterone Medroxyprogestero//e acerbate 17'0t-HydroXyprogester0ne~ 17-n°caproat¢ ! 7-ct-Hydroxyprogestcrone17.n,~ap/'oate "
Number of patients
Partial rc.pome,
9 23 9
2 9 2
19 10
I ~
6
l
76
18
(24%)
COnclusions E x t e n s i v e b a s i c and clinical investigation-is continuing in an effort to define hormone fee:eptor distribution and clinical relevance in m a n y neoplasms. Some endometrial carcinomas ` c o n t a i n measurable ER: a n d PR, and some prostatic carcinomas contain a n d r o g e n receptors. I t is probable that some malignant melanomas, renal carcinomas a n d o v a r i a n c a r c i n o m a s also c o n t a i n E R o r P R o r both. Clinical correlation between receptor tilers and response to therapy is dtilI eitheria:ck~ng or tenuous for all these tt, mors, a n d it wouid be premature to base therapy for these tumors on receptor d a t a except i n clinical investigations. T h e receptor d a t a that is b e i n g r e p o r t e d shouId be approached criticallyt~by the i n d i v i d u a l reader with the caveat that initial lpublications are usually more optiiniStic daa~x final definitive facts. TO be c 0 n v i n c i n g a n : i n v e s t i g a t i 0 n should prove that wlmt is beingmeasurediS a c t u a l l y r e c e p t o r and that the receptor is in the tumori noi in-adjacent non-neoplastic dssue: Specifically, these questions should be considered by the reader. I. Has care been taken: to eliminate measurement of c o n t a m i n a t i n g se~Cumproteins which also bind the ligand (hormone) whose receptor is being measured ?
192
M. A. FRIEDMAN, P. G. H O F F M A N AND H. W. J O N E S
2. I f a synthetic ligand is used, is the !igand specific for the receptor which is purported to be measured ? (SR-1881 binds avidly to both androgen and progesterone red,eptors; R-5020 binds.slightly to cortisol receptors a s well as to progesterone receptors). 3. Is adequate care taken to characterize the binding protein as receptor ? Thiscould be accomplished either by measuring its affinity for ligandor by characterizing its unique mobilitypattern (e.g., in a sucrose gradient;-in an electrophoretic field, or by using 'isoelectric focusing procedures) . 4. Is there adequate assurance that tumor tissue; rather than surrounding normal or hyperplastic tissue, contains the receptor that :is being measured ? T h i s point is espe6iM1g~critical i n assessing results Of primary endometrial and prostatic tumor studies, sincel tissue adjacent to t h e tumor may contain more receptor than the tumor itself. 5. When receptor assays are reported to be_negative, what: is the ttireshold of the analytic techn!que being u s e d ? W h e n reported as positive, is there assurance that the result is significantly different :from zero ? Are the criteria for positivity and negativity explained satisfactorily ? 6, Ih comparing receptor titers in tumors from diiTerent individuals, a r e the differences in endogenous hormones taken into account ? We have stressed the preliminary nature of the current data concerning receptors in tumors o~her than breast cancer. ~or the tumors discussed here, improved technology for relia.ble measurement of receptors is sorely nebded, iWell:designed clinical studies :indicating the relative influence of receptor titers on results ofendocrine and non-endocrine therapy a r e required in order tb--apply receptor m e a s u r e m e n ~ rationally in clinical management. Receptors m a y also b e indicat0rs ofprognosisirrespectiye of the therapy used. Will receptor measurements improvelselection of therapy or simply predict which patients are likel~ to sum,ive longer independent of therapy ? Both possibilities are equaily plausible at present. With So manyquesti0ns a s y e t unanswered;obvi0uSly t h e investigation of hormone receptors i n malignantr disease~Wiii continue:to bc one of the mbst vigorously pursued areasi;o-f onco!ogic research.
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