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Fertility Preservation in Prepubertal Girls Prior to Chemotherapy and Radiotherapy—Review of the Literature
Mini-Review Fertility Preservation in Prepubertal Girls Prior to Chemotherapy and Radiotherapy—Review of the Literature B. Lawrenz MD *, R. Rothmund MD, E. Neunhoeffer MD, S. Huebner MD, M. Henes MD Womens University Hospital, Tuebingen, Germany
a b s t r a c t Significant improvement in the survival rates of children with pediatric cancers has been achieved over the last 25 years, so the number of long-term survivors is increasing and their subsequent quality of life is of increasing importance. One of the most serious side effects of chemotherapy or radiotherapy is damage to the ovarian function, which can lead to loss of fertility. The degree of this damage depends on the substances used, the dose of radiotherapy reaching the ovaries, and the age of the girl at the time of treatment. Up to now, the only established method of fertility preservation has been cryoconservation of fertilized egg cells or embryos, but this is not possible in prepubertal girls because of their sexual immaturity. Removal of ovarian tissue and subsequent cryoconservation with the option of later orthotopic retransplantation is therefore an option to these girls. This method can lead to pregnancy and birth in adult women. Up to now there are no studies about the retransplantation of ovarian tissue which was removed before puberty. Displacement of the ovaries away from the radiation field before radiation to the pelvic area can be considered; however, the data is controversial. One problem in the use of fertility preservation methods in these very young patients is that they undergo procedures which, because of their age, they mostly do not understand and the parents must make a decision based on the assumed later wishes of their daughter. Key Words: Fertility preservation, Prepubertal girls, Ovarian toxicity, Chemotherapy, Radiotherapy, Fertility
Introduction
Approximately 1,800 cancer cases are diagnosed annually in Germany in children under 15 years of age. This is equivalent to an incidence of about 14 cases per 100,000 children in this age group. The mean age of onset is 5 years and 8 months, and boys are affected 1.2 times more often than girls. The most common illnesses are leukemias (34.1%), CNS tumors (22.1%) and lymphomas (11.8%).1 In the USA, cancer is the second most common cause of death in children aged between 1 and 14 years.2 As a result of advances in chemotherapy, a significant improvement in the 5-year survival rate has been achieved in all forms of cancer over the last 25 years, from 58% in 1975e1977 to 80% between 1996 and 2010.2,3 The number of long-term survivors of childhood cancer has consequently increased and because of this rising life expectancy, improving their subsequent quality of life has been increasingly brought to the attention of oncologists, patients, and their families. A particularly sensitive subject is the future fertility of surviving patients, because one of the most serious side effects of chemotherapy and radiotherapy is damage to the ovaries. Depending on the chemotherapy used, the possible use of radiotherapy to the pelvic area, and the age of the
Conflict of interest: We declare that we have no conflict of interest. * Address correspondence to: Dr. med. Barbara Lawrenz, Womens University € bingen, Calwerstr. 7, 72076 Tuebingen, Germany. Hospital Tu E-mail address: [email protected] (B. Lawrenz).
young patient at the time of treatment, reduction in or loss of ovarian function can result, and therefore infertility. As a result of advances in reproductive medicine and the development of fertility preservation methods, it has become possible over the last few years to integrate these preservation techniques into the oncological treatment concept in adult women.4 The idea of conceiving a child after surviving cancer has therefore become a reality. However, only a few of these techniques can be carried out in prepubertal girls. We describe the consequences of chemotherapy and radiotherapy on future fertility and discusses the fertility preservation methods which are currently available for these young girls. Effects of Chemotherapy on the Ovarian Function
Damage to the ovarian function in girls can occur as a result of chemotherapy and also after pelvic radiotherapy or total body irradiation. Radiotherapy to the head can lead to disruption to the hypothalamic-hypophyseal-ovarian axis with later disturbance to the ovarian function, without the ovary itself being affected. Follow-up studies on long-term survivors of childhood cancer have shown that about 8% of all survivors develop premature ovarian insufficiency (POI) compared to 0.8% of their healthy siblings.5 If radiotherapy was also used, the number of survivors with POF increased to 30e40%.5,6 Chemotherapeutic agents which reach the ovaries lead to damage to the primordial follicles. The greatest numbers
1083-3188/$ - see front matter Ó 2012 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. doi:10.1016/j.jpag.2011.05.009
B. Lawrenz et al. / J Pediatr Adolesc Gynecol 25 (2012) 284e288
of follicles are present in the ovary during the foetal period. Afterwards there is a steady decline in the number of follicles: a newborn baby girl has a “pool” of 106 oocytes; this pool decreases to about 3 105 during puberty. Over the course of the reproductive phase, about 300e400 oocytes are normally ovulated.7 The follicle pool diminishes exponentially with age, with a significant increase in the degeneration rate at age of 37e38 years. The menopause is reached when there are 1000 follicles or less, and the low number of follicles can no longer sustain the hormonal cycle regulation.8 It is presumed that the detrimental effect on the ovary of cytotoxic agents is caused by damage to the peri-oocyte granulosa cells in the ovaries. Damage to ovarian tissue as a result of the use of cytotoxic agents is irreversible. Histological samples of ovarian tissue after chemotherapy have shown images which range from a reduction in the follicle count to complete failure.9 According to Sonmezer et al,10 chemotherapeutic agents can be grouped according to their ovarian toxicity. Table 1 lists the ovarian toxicity of the chemotherapeutic agents. Because of the use of these substances in combination with several other substances in treatment regimens, it is often difficult to assess the ovarian toxicity of the individual substances. Cyclophosphamide is more cytotoxic than other substances because it damages dormant as well as dividing cells. Experiments on mice have shown that increasing doses lead to an exponential increase in follicle damage.11 Meirow12 developed a logistic regression model to calculate the risk of ovarian damage in a study using young cancer patients who were exposed to chemotherapy with alkylating substances. The use of alkylating substances was accompanied by an odds ratio (OR) of 4.0 for ovarian damage and was therefore significantly higher compared to the use of platinum agents (OR 5 1.8), plant alkaloids (OR 1.2), and anti-metabolites (OR ! 1). The high number of primordial follicles in prepubertal girls makes the ovaries less sensitive to radiotherapy than in postpubescent girls. Damage to the ovaries by radiotherapy depends of the radiation dose, the radiation field, the radiotherapy dose fractionation, and the age of the patient at the time of treatment.13,14 The actual radiotherapy doses to the ovaries that lead to sterility are 20.3 Gy at the time of birth, 18.4 Gy at the age of 10, 16.5 Gy at age 20, and 14.3 Gy at the age of 30 years. Depending on the dose reaching the ovaries, the age at which premature ovarian failure occurs can be calculated using the Faddy-Gosden Model with a 95% confidence interval.15 Radiotherapy to the pelvic area, but also total body and abdominal irradiation, can affect the uterus as well as the
ovaries. Consequences of radiotherapy are diminished uterine perfusion, reduced uterine volume, reduced endometrial thickness, and a loss of elasticity of the uterine musculature. The effect is greater with prepubertal radiotherapy. Women who first received radiotherapy after puberty have larger uteri and a greater chance of a live birth than women with prepubertal radiotherapy.16 Radiotherapy to the cranium can lead to disruption to the hypothalamic-hypophyseal-ovarian axis and therefore to the ovarian function, although the gonads are not directly affected by the radiotherapy. Patients who received cranial irradiation with doses of 35e45 Gy had reduced serum levels of gonadotrophins. This led to reduced sex hormone levels and delayed onset of puberty.17 The degree of damage to the ovaries depends on the planned chemotherapy agents and the age of the patient, and an exact prediction of the remaining ovarian function is therefore difficult. Table 2 gives an estimate of the risk of developing subfertility according to Wallace et al,18 depending on the illness and the established treatment regimens. Benign systemic diseases such as metachromatic adrenoleukodystrophies, immune defects and severe rheumatic diseases can also necessitate cytotoxic treatment which can lead to ovarian damage. Fertility Preservation Methods
The following fertility preservation treatment options are available to adult women: administration of a GnRH analogue (5GnRH protection), hormonal stimulation to collect oocytes with cryoconservation of fertilized or unfertilized oocytes, removal of ovarian tissue for cryoconservation with the option of later re-transplantation, ovarian transposition if pelvic radiotherapy is performed and a combination of the various methods. Because of their sexual immaturity and the absence of maturation of the hypothalamic-hypophyseal-ovarian axis, the options for fertility protection in prepubertal girls are Table 2 Risk of Developing Subfertility, According to Wallace et al18 Low risk
Medium risk
Table 1 Ovarian Toxicity of the Chemotherapeutic Agents According to Sonmezer et al10 High risk
Medium risk
Low risk
Cyclophosphamide Ifosfamide Chlormethine Busulfan Melphalan Chlorambucil
Cisplatin Carboplatin Doxorubicin
Vincristine Methotrexate Dactinomycin Bleomycin Mercaptopurine Vinblastine
285
High risk
Acute lymphoblastic leukemia Wilms tumor Soft-tissue sarcoma: stage I Germ-cell tumors (with gonadal preservation and no radiotherapy) Retinoblastoma Brain tumor: surgery only, cranial irradiation ! 24 Gy Acute myeloblastic leukemia Hepatoblastoma Osteosarcoma Ewing0 s sarcoma stage II or III Neuroblastoma Non-Hodgkin lymphoma Hodgkin disease: alternating treatment Brain tumor: craniospinal radiotherapy, cranial irradiation O 24 Gy Whole-body irradiation Localized pelvic radiotherapy Chemotherapy conditioning for bone-marrow transplantation Hodgkin disease: treatment with alkylating drugs Soft-tissue sarcoma: stage IV Metastatic Ewing0 s sarcoma
286
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limited to the removal and cryoconservation of ovarian tissue and ovarian transposition if radiotherapy of the pelvis is performed. Removal of Ovarian Tissue for Cryoconservation
Ovarian tissue, which is rich in primordial follicles, is removed and cryoconserved with the option of later retransplantation to re-establish fertility and hormone production. Recommendations differ in the literature as to whether ovarian tissue should be removed in the form of strips from the ovarian cortex, or whether the whole ovary should be removed.18,19 To avoid damage to the ovarian tissue, removal should be performed without trauma or thermal damage to the tissue if possible. Otherwise less vital tissue will be available for cryopreservation and later re-transplantation as a result. It should also be noted that arrest of bleeding after tissue removal can lead to damage to the remaining part of the ovary in situ in very young girls with a small ovarian volume. The surgical procedure necessary for this option can normally be performed using minimally invasive laparoscopy. If other surgical procedures are necessary as part of the planned treatment, they can be performed at the same time. After cancer is cured and the patient wishes to conceive, possibilities for the later use of the cryopreserved ovarian tissue are in vitro maturation of primordial follicles and later heterotopic or orthotopic autologous retransplantation. The possibility of xenografting the ovarian tissue, for example to immunodeficient mice with subsequent hormonal stimulation of the mice to collect oocytes is ethically very controversial and therefore not discussed at this time. The process of in vitro maturation of the immature follicle in the removed ovarian tissue up to metaphase could be a possibility in the future. The growth of follicles in vitro from a primordial follicle to the endpoint of an oocyte suitable for fertilization has only been possible in mice up to now. This procedure has led to healthy offspring.20 Because of the limited availability of human ovarian tissue, the efforts to establish efficient in vitro culture methods to grow follicles out of human ovaries have lagged behind. Outside the natural environment, the follicles are subjected to unphysiological conditions such as changing of temperature and oxygen tension. A review by Smitz et al21 describes the actual developments of in vitro maturation of follicles in ovarian tissue. The advantage of this process is that the tissue does not need to be re-transplanted in order to collect egg cells suitable for fertilization, which avoids the danger of re-transplanting malignant cells after surviving cancer. If the tissue is re-transplanted, both heterotopic and autologous re-transplantation are possible. The advantage of heterotopic re-transplantation under the skin in the underarm area or the abdominal wall is that no new intraabdominal procedure has to be performed. Follicle puncture to collect oocytes after hormonal stimulation would also be technically simple. Using this technique, egg cells have been collected and fertilized and a fertilized egg cell developed into a 4-cell embryo. However, a pregnancy was not achieved.22
Physiological conditions are restored with retransplantation in the adnexal space, so a pregnancy occurring spontaneously is possible. This option has been performed successfully in adult women and 10 known pregnancies after re-transplantation are mentioned in the literature.23 From experience in adults, it has been shown that ovarian function can be re-established up to a certain extent after transplantation of ovarian tissue. However, the efficacy of using cryoconserved ovarian tissue is reduced compared to the use of “fresh” non-cryoconserved tissue.24 In monozygotic twins, discordant for premature ovarian failure, transplantation of heterologous “fresh” ovarian tissue led to successful pregnancies.25 Proof of long-term efficacy and life expectancy of the ovarian transplant is not yet available. An important point that must be discussed is the risk of re-transplanting malignant cells with the ovarian tissue. Excluding of the presence of malignant cells in the ovarian tissue could be performed using histological techniques; however, on a cautionary note, only a small and therefore doubtfully representative tissue sample can be examined. In patients with Hodgkin’s disease, it appears to be certain that there is no risk of contamination of the removed ovarian tissue with malignant cells.26 An exception is Burkitt’s lymphoma.27 According to current data, ovarian tissue cannot be retransplanted in patients with leukemia because of the systemic nature of the disease. Ovarian tissue could only be removed and cryoconserved in this situation in the hope that in vitro maturation of the oocytes will be possible in the future. Several study groups have reported on ovarian tissue removal on girls and adolescents,19,23,28,29 although only in Poirot’s study group,29 the mean age was 6.1 years. The mean age of the young patients treated in the other groups mentioned was between 10.423 and 13.5 years.28 None of the study groups described complications occurring as part of the ovarian tissue removal process. A maximum of 5 days elapsed between ovarian tissue removal and the start of chemotherapy in the oncology patients.23 Up to now, there are no reports about re-transplantation of ovarian tissue which was removed before puberty. Admittedly, this technique was only developed during the last decade, and the report on the first retransplantation of cryoconserved ovarian tissue is from the year 2000.30 Patients who had ovarian tissue removed before puberty or during adolescence are usually still too young to enquire about re-transplantation of the tissue. Over the next few years, significant experience is expected to be gained in the field of cryoconservation and retransplantation. Ovarian Transposition
The aim of ovarian transposition before planned pelvic radiotherapy or the caudal spine is to relocate the ovaries away from the radiation field and therefore to reduce the radiation dosage reaching the ovaries. One or both of the ovaries are transposed either behind the uterus,
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craniolaterally or under the diaphragm. Scattered radiation can reduce the effectiveness of this technique. There is controversial data on the efficacy of ovarian transposition in the literature: Terenziani et al31 reported on 14 pregnancies with 12 live births in 11 women suffering from Hodgkin’s disease. The mean age at diagnosis and performance of this technique was 13 years (range 9e22 years), and the patients underwent retro-uterine ovarian transposition as part of a staging laparotomy between 1972 and 1988. A current review32 found the incidence of POI to be 50e90% after ovarian transposition. Alongside the risk of the surgical procedure itself, there is a danger of disturbed blood flow with tube infarction, the development of ovarian cysts and chronic pain after craniolateral transposition of the ovaries.33 To naturally achieve a pregnancy at a later date, a further surgical procedure is necessary to relocate the ovaries. Without relocation, extracorporeal fertilization must be performed. Treatment monitoring and especially egg cell collection would be much more difficult because of the cranial positioning of the ovaries. As a combination of radiotherapy and chemotherapy can have a negative effect on the ovarian reserve because of the substances used, ovarian transposition should be very critically considered in this situation. Counselling Situation
The possibility of a child becoming a mother at a later date has a low priority in girls with oncological disease compared to the worries about them surviving. Nevertheless, the effects of cancer treatment on the reproductive function and later fertility should be discussed with the patients and their families before the start of treatment. Anderson et al34 investigated the approach to counselling on the effects of chemotherapy and/or radiotherapy on fertility: while the negative effect of treatment on the ovarian function was discussed with 86% of the postpubertal girls and their parents, it was discussed only with 60% of the prepubertal girls. The most common reason for not discussing this was that no significant risk of developing infertility was seen (79%). Nevertheless, the study showed that there is a high sensitivity to this subject by the pediatric oncologists. This was also confirmed in another study.35 However, 64% of the oncologists had difficulty in finding a suitable information center regarding to fertility preservation methods. The FertiPROTEKT network was founded in Germany in 2006, with the aim of counselling patients before chemotherapy, and the performance of fertility preservation techniques including recording and scientifically evaluating the data.36 In 2007, the Task Force of the European Society of Human Reproduction and Embryology “Fertility preservation in severe diseases” was established (www.eshre.eu). The Task Force involves specialists from all areas of reproductive medicine, reproductive biology and psychology and focuses on the publication of review articles on different topics of fertility preservation and the organization of workshops. In addition, the American Society for Reproductive Medicine established the Fertility Preservation
287
Special Interest Group to promote knowledge among health care workers and the public on infertility induced by cancer therapy (www.asrm.org). Ethical Considerations
The aim of fertility preservation methods is to protect ovarian function from the negative effects of cytotoxic treatments or radiotherapy. The only established technique up to now is the cryoconservation of fertilized egg cells or embryos, depending on the legislation of the respective countries. This technique cannot be used in prepubertal girls because of their sexual immaturity. All other methods can only be regarded as experimental at the moment.37 Up to the age 18 or—depending on the law—age 21, children are not able to or only partly able to give consent. Considering their age, it can be assumed that prepubertal girls cannot understand the significance of a possible loss of fertility and the meaning of fertility preservation methods. The parents must therefore decide, and assume the possible future wishes of the girl. A decision for or against fertility preservation methods can only be made by the oncologists, specialists in reproductive medicine, the parents, and wherever possible, the young patient who is affected after comprehensive counselling on the prospects and risks of each technique in relation to the risk of the risk of loss of fertility. Acknowledgment
We are greatly indebted to Mrs. Elizabeth Kraemer for reviewing our manuscript. References 1. Gesundheitsberichterstattung des Bundes, Robert-Koch-Institut: Krebs in € €ufigkeiten und Trends 2008;6. Uberarbeitete Deutschland 2003 e 2004. Ha Auflage:102 2. Jemal A, Siegel R, Xu J, et al: Cancer Statistics, 2010. CA Cancer J Clin 2010; 60: 277 3. Ries LA, Eisner MP, Kosary CL, et al: SEER cancer statistics review, 1973 e 1998. Bethesda, MD, National Cancer Institute, 2001 4. Lawrenz B, Jauckus J, Kupka M, et al: Fertility preservation in O 1000 patients: patient’s characteristics, spectrum, efficacy and risks of applied preservation techniques. Arch Gynecol Obstet 2011; 283:651 5. Sklar CA, Mertens AC, Mitby P, et al: Premature menopause in survivors of childhood cancer: a report from the childhood cancer survivor study. J Natl Cancer Inst 2006; 98:890 6. Byrne J, Fears TR, Gail MH, et al: Early menopause in long-term survivors of cancer during adolescence. Am J Obstet Gynecol 1992; 166:788 7. Chabbert Buffet N, Djakoure C, Maitre SC, et al: Regulation of the human menstrual cycle. Front Neuroendocrinol 1998; 19:151 8. Faddy MJ, Gosden RG, Gougeon A, et al: Accelerated disappearance of ovarian follicles in mid-life: implications for forecasting menopause. Hum Reprod 1992; 7:1342 9. Warne GL, Fairley KF, Hobbs JB, et al: Cyclophosphamide induced ovarian failure. N Engl J Med 1973; 289:1159 10. Sonmezer M, Oktay K: Fertility preservation in female patients. Hum Reprod Update 2004; 10:251 11. Meirow D, Lewis H, Nugent D, et al: Subclinical depletion of primordial follicular reserve in mice treated with cyclophosphamide: clinical importance and proposed accurate investigative tool. Hum Reprod 1999; 14:1903 12. Meirow D: Reproduction post-chemotherapy in young cancer patients. Mol Cell Endocrinol 2000; 169:123 13. Wallace WH, Shalet SM, Hendry JH, et al: Ovarian failure following abdominal irradiation in childhood: the radiosensitivity of the human oocyte. Br J Radiol 1989; 62:995 14. Sanders JE, Hawley J, Levy W, et al: Pregnancies following high-dose cyclophosphamide with or without high-dose busulfan or total-body irradiation and bone marrow transplantation. Blood 1996; 87:3045
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15. Wallace WH, Thomson AB, Saran F, et al: Predicting age of ovarian failure after radiation to a field that includes the ovaries. Int J Radiat Oncol Biol Phy 2005; 62:738 16. Bath LE, Wallace WH, Critchley HO: Late effects of the treatment of childhood cancer on the female reproductive system and the potential for fertility preservation. BJOG 2002; 109:107 17. Littley MD, Shalet SM, Beardwell CG, et al: Radiation-induced hypopituitarism is dose-dependent. Clin Endocrinol 1989; 31:363 18. Wallace WH, Anderson RA, Irvine DS: Fertility preservation for young patients with cancer: who is at risk and what can be offered? Lancet Oncol 2005; 6: 209 19. Schmidt KT, Larsen EC, Andersen CY, et al: Risk of ovarian failure and fertility preserving methods in girls and adolescents with a malignant disease. BJOG 2010; 117:163 20. O’Brien MJ, Pendola JK, Eppig JJ: A revised protocol for in vitro development of mouse oocytes from primordial follicles dramatically improves their developmental competence. Biol Reprod 2003; 68:1682 21. Smitz J, Dolmans MM, Donnez J, et al: Current achievement and future research directions in ovarian tissue culture, in vitro follicle development and transplantation: implications for fertility preservation. Hum Reprod Update 2010; 16:395 22. Oktay K, Buyuk E, Veeck L, et al: Embryo development after heterotopic transplantation of cryopreserved ovarian tissue. Lancet 2004; 363:837 23. Jadoul P, Dolmans MM, Donnez J: Fertility preservation in girls during childhood: is it feasible, efficient and safe and to whom should it be proposed? Hum Reprod Update 2010; 16:617 24. Bedaiwy MA, El-Nashar SA, El Saman AM, et al: Reproductive outcome after transplantation of ovarian tissue: a systematic review. Hum Reprod 2008; 23: 2709 25. Silber SJ, DeRosa M, Pineda J, et al: A series of monozygotic twins discordant for ovarian failure: ovary transplantation (cortical versus microvascular) and cryopreservation. Hum Reprod 2008; 23:1531
26. Kim SS, Radford J, Harris M, et al: Ovarian tissue harvested from lymphoma patients to preserve fertility may be safe for autotransplantation. Hum Reprod 2001; 16:2056 27. Osborne B, Robboy SJ: Lymphomas or leukemia presenting as ovarian tumors. An analysis of 42 cases. Cancer 1983; 52:1933 28. Feigin E, Abir R, Fisch B, et al: Laparoscopic ovarian tissue preservation in young patients at risk for ovarian failure as a result of chemotherapy/irradiation for primary malignancy. J Pediatr Surg 2007; 42:862 res L, Genestie C, et al: [Ovarian tissue cryopreservation for 29. Poirot C, Brugie prepubertal girls: indications and feasibility]. [Article in French] Gynecol Obstet Fertil 2005; 33:799 30. Oktay K, Karlikaya G: Ovarian function after transplantation of frozen, banked autologous ovarian tissue. N Engl J Med 2000; 342:1919 31. Terenziani M, Piva L, Meazza C, et al: Oophoropexy: a relevant role in preservation of ovarian function after pelvic irradiation. Fertil Steril 2009; 91: 935.e15 32. Wo JY, Viswanathan AN: Impact of radiotherapy on fertility, pregnancy, and neonatal outcomes in female cancer patients. Int J Radiat Oncol Biol Phys 2009; 73:1304 33. Meirow D, Nugent D: The effects of radiotherapy and chemotherapy on female reproduction. Hum Reprod Update 2001; 7:535 34. Anderson RA, Weddell A, Spoudeas HA, et al: Do doctors discuss fertility issues before they treat young patients with cancer? Hum Reprod 2008; 23:2246 35. Goodwin T, Elizabeth Oosterhuis B, Kiernan M, et al: Attitudes and practices of pediatric oncology providers regarding fertility issues. Pediatr Blood Cancer 2007; 48:80 € r fertilita €tsprotektive 36. Lawrenz B, von Wolff M: FertiPROTEKT e Netzwerk fu € r Reproduktionsmedizin Maßnahmen bei Chemo- und Strahlentherapie. Journal fu und Endokrinologie 2010; 7:147 37. Lee SJ, Schover L, Partridge AH, et al: American Society of Clinical Oncology recommendations on fertility preservation in cancer patients. J Clin Oncol 2006; 24:2917
a b s t r a c t Significant improvement in the survival rates of children with pediatric cancers has been achieved over the last 25 years, so the number of long-term survivors is increasing and their subsequent quality of life is of increasing importance. One of the most serious side effects of chemotherapy or radiotherapy is damage to the ovarian function, which can lead to loss of fertility. The degree of this damage depends on the substances used, the dose of radiotherapy reaching the ovaries, and the age of the girl at the time of treatment. Up to now, the only established method of fertility preservation has been cryoconservation of fertilized egg cells or embryos, but this is not possible in prepubertal girls because of their sexual immaturity. Removal of ovarian tissue and subsequent cryoconservation with the option of later orthotopic retransplantation is therefore an option to these girls. This method can lead to pregnancy and birth in adult women. Up to now there are no studies about the retransplantation of ovarian tissue which was removed before puberty. Displacement of the ovaries away from the radiation field before radiation to the pelvic area can be considered; however, the data is controversial. One problem in the use of fertility preservation methods in these very young patients is that they undergo procedures which, because of their age, they mostly do not understand and the parents must make a decision based on the assumed later wishes of their daughter. Key Words: Fertility preservation, Prepubertal girls, Ovarian toxicity, Chemotherapy, Radiotherapy, Fertility
Introduction
Approximately 1,800 cancer cases are diagnosed annually in Germany in children under 15 years of age. This is equivalent to an incidence of about 14 cases per 100,000 children in this age group. The mean age of onset is 5 years and 8 months, and boys are affected 1.2 times more often than girls. The most common illnesses are leukemias (34.1%), CNS tumors (22.1%) and lymphomas (11.8%).1 In the USA, cancer is the second most common cause of death in children aged between 1 and 14 years.2 As a result of advances in chemotherapy, a significant improvement in the 5-year survival rate has been achieved in all forms of cancer over the last 25 years, from 58% in 1975e1977 to 80% between 1996 and 2010.2,3 The number of long-term survivors of childhood cancer has consequently increased and because of this rising life expectancy, improving their subsequent quality of life has been increasingly brought to the attention of oncologists, patients, and their families. A particularly sensitive subject is the future fertility of surviving patients, because one of the most serious side effects of chemotherapy and radiotherapy is damage to the ovaries. Depending on the chemotherapy used, the possible use of radiotherapy to the pelvic area, and the age of the
Conflict of interest: We declare that we have no conflict of interest. * Address correspondence to: Dr. med. Barbara Lawrenz, Womens University € bingen, Calwerstr. 7, 72076 Tuebingen, Germany. Hospital Tu E-mail address: [email protected] (B. Lawrenz).
young patient at the time of treatment, reduction in or loss of ovarian function can result, and therefore infertility. As a result of advances in reproductive medicine and the development of fertility preservation methods, it has become possible over the last few years to integrate these preservation techniques into the oncological treatment concept in adult women.4 The idea of conceiving a child after surviving cancer has therefore become a reality. However, only a few of these techniques can be carried out in prepubertal girls. We describe the consequences of chemotherapy and radiotherapy on future fertility and discusses the fertility preservation methods which are currently available for these young girls. Effects of Chemotherapy on the Ovarian Function
Damage to the ovarian function in girls can occur as a result of chemotherapy and also after pelvic radiotherapy or total body irradiation. Radiotherapy to the head can lead to disruption to the hypothalamic-hypophyseal-ovarian axis with later disturbance to the ovarian function, without the ovary itself being affected. Follow-up studies on long-term survivors of childhood cancer have shown that about 8% of all survivors develop premature ovarian insufficiency (POI) compared to 0.8% of their healthy siblings.5 If radiotherapy was also used, the number of survivors with POF increased to 30e40%.5,6 Chemotherapeutic agents which reach the ovaries lead to damage to the primordial follicles. The greatest numbers
1083-3188/$ - see front matter Ó 2012 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. doi:10.1016/j.jpag.2011.05.009
B. Lawrenz et al. / J Pediatr Adolesc Gynecol 25 (2012) 284e288
of follicles are present in the ovary during the foetal period. Afterwards there is a steady decline in the number of follicles: a newborn baby girl has a “pool” of 106 oocytes; this pool decreases to about 3 105 during puberty. Over the course of the reproductive phase, about 300e400 oocytes are normally ovulated.7 The follicle pool diminishes exponentially with age, with a significant increase in the degeneration rate at age of 37e38 years. The menopause is reached when there are 1000 follicles or less, and the low number of follicles can no longer sustain the hormonal cycle regulation.8 It is presumed that the detrimental effect on the ovary of cytotoxic agents is caused by damage to the peri-oocyte granulosa cells in the ovaries. Damage to ovarian tissue as a result of the use of cytotoxic agents is irreversible. Histological samples of ovarian tissue after chemotherapy have shown images which range from a reduction in the follicle count to complete failure.9 According to Sonmezer et al,10 chemotherapeutic agents can be grouped according to their ovarian toxicity. Table 1 lists the ovarian toxicity of the chemotherapeutic agents. Because of the use of these substances in combination with several other substances in treatment regimens, it is often difficult to assess the ovarian toxicity of the individual substances. Cyclophosphamide is more cytotoxic than other substances because it damages dormant as well as dividing cells. Experiments on mice have shown that increasing doses lead to an exponential increase in follicle damage.11 Meirow12 developed a logistic regression model to calculate the risk of ovarian damage in a study using young cancer patients who were exposed to chemotherapy with alkylating substances. The use of alkylating substances was accompanied by an odds ratio (OR) of 4.0 for ovarian damage and was therefore significantly higher compared to the use of platinum agents (OR 5 1.8), plant alkaloids (OR 1.2), and anti-metabolites (OR ! 1). The high number of primordial follicles in prepubertal girls makes the ovaries less sensitive to radiotherapy than in postpubescent girls. Damage to the ovaries by radiotherapy depends of the radiation dose, the radiation field, the radiotherapy dose fractionation, and the age of the patient at the time of treatment.13,14 The actual radiotherapy doses to the ovaries that lead to sterility are 20.3 Gy at the time of birth, 18.4 Gy at the age of 10, 16.5 Gy at age 20, and 14.3 Gy at the age of 30 years. Depending on the dose reaching the ovaries, the age at which premature ovarian failure occurs can be calculated using the Faddy-Gosden Model with a 95% confidence interval.15 Radiotherapy to the pelvic area, but also total body and abdominal irradiation, can affect the uterus as well as the
ovaries. Consequences of radiotherapy are diminished uterine perfusion, reduced uterine volume, reduced endometrial thickness, and a loss of elasticity of the uterine musculature. The effect is greater with prepubertal radiotherapy. Women who first received radiotherapy after puberty have larger uteri and a greater chance of a live birth than women with prepubertal radiotherapy.16 Radiotherapy to the cranium can lead to disruption to the hypothalamic-hypophyseal-ovarian axis and therefore to the ovarian function, although the gonads are not directly affected by the radiotherapy. Patients who received cranial irradiation with doses of 35e45 Gy had reduced serum levels of gonadotrophins. This led to reduced sex hormone levels and delayed onset of puberty.17 The degree of damage to the ovaries depends on the planned chemotherapy agents and the age of the patient, and an exact prediction of the remaining ovarian function is therefore difficult. Table 2 gives an estimate of the risk of developing subfertility according to Wallace et al,18 depending on the illness and the established treatment regimens. Benign systemic diseases such as metachromatic adrenoleukodystrophies, immune defects and severe rheumatic diseases can also necessitate cytotoxic treatment which can lead to ovarian damage. Fertility Preservation Methods
The following fertility preservation treatment options are available to adult women: administration of a GnRH analogue (5GnRH protection), hormonal stimulation to collect oocytes with cryoconservation of fertilized or unfertilized oocytes, removal of ovarian tissue for cryoconservation with the option of later re-transplantation, ovarian transposition if pelvic radiotherapy is performed and a combination of the various methods. Because of their sexual immaturity and the absence of maturation of the hypothalamic-hypophyseal-ovarian axis, the options for fertility protection in prepubertal girls are Table 2 Risk of Developing Subfertility, According to Wallace et al18 Low risk
Medium risk
Table 1 Ovarian Toxicity of the Chemotherapeutic Agents According to Sonmezer et al10 High risk
Medium risk
Low risk
Cyclophosphamide Ifosfamide Chlormethine Busulfan Melphalan Chlorambucil
Cisplatin Carboplatin Doxorubicin
Vincristine Methotrexate Dactinomycin Bleomycin Mercaptopurine Vinblastine
285
High risk
Acute lymphoblastic leukemia Wilms tumor Soft-tissue sarcoma: stage I Germ-cell tumors (with gonadal preservation and no radiotherapy) Retinoblastoma Brain tumor: surgery only, cranial irradiation ! 24 Gy Acute myeloblastic leukemia Hepatoblastoma Osteosarcoma Ewing0 s sarcoma stage II or III Neuroblastoma Non-Hodgkin lymphoma Hodgkin disease: alternating treatment Brain tumor: craniospinal radiotherapy, cranial irradiation O 24 Gy Whole-body irradiation Localized pelvic radiotherapy Chemotherapy conditioning for bone-marrow transplantation Hodgkin disease: treatment with alkylating drugs Soft-tissue sarcoma: stage IV Metastatic Ewing0 s sarcoma
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limited to the removal and cryoconservation of ovarian tissue and ovarian transposition if radiotherapy of the pelvis is performed. Removal of Ovarian Tissue for Cryoconservation
Ovarian tissue, which is rich in primordial follicles, is removed and cryoconserved with the option of later retransplantation to re-establish fertility and hormone production. Recommendations differ in the literature as to whether ovarian tissue should be removed in the form of strips from the ovarian cortex, or whether the whole ovary should be removed.18,19 To avoid damage to the ovarian tissue, removal should be performed without trauma or thermal damage to the tissue if possible. Otherwise less vital tissue will be available for cryopreservation and later re-transplantation as a result. It should also be noted that arrest of bleeding after tissue removal can lead to damage to the remaining part of the ovary in situ in very young girls with a small ovarian volume. The surgical procedure necessary for this option can normally be performed using minimally invasive laparoscopy. If other surgical procedures are necessary as part of the planned treatment, they can be performed at the same time. After cancer is cured and the patient wishes to conceive, possibilities for the later use of the cryopreserved ovarian tissue are in vitro maturation of primordial follicles and later heterotopic or orthotopic autologous retransplantation. The possibility of xenografting the ovarian tissue, for example to immunodeficient mice with subsequent hormonal stimulation of the mice to collect oocytes is ethically very controversial and therefore not discussed at this time. The process of in vitro maturation of the immature follicle in the removed ovarian tissue up to metaphase could be a possibility in the future. The growth of follicles in vitro from a primordial follicle to the endpoint of an oocyte suitable for fertilization has only been possible in mice up to now. This procedure has led to healthy offspring.20 Because of the limited availability of human ovarian tissue, the efforts to establish efficient in vitro culture methods to grow follicles out of human ovaries have lagged behind. Outside the natural environment, the follicles are subjected to unphysiological conditions such as changing of temperature and oxygen tension. A review by Smitz et al21 describes the actual developments of in vitro maturation of follicles in ovarian tissue. The advantage of this process is that the tissue does not need to be re-transplanted in order to collect egg cells suitable for fertilization, which avoids the danger of re-transplanting malignant cells after surviving cancer. If the tissue is re-transplanted, both heterotopic and autologous re-transplantation are possible. The advantage of heterotopic re-transplantation under the skin in the underarm area or the abdominal wall is that no new intraabdominal procedure has to be performed. Follicle puncture to collect oocytes after hormonal stimulation would also be technically simple. Using this technique, egg cells have been collected and fertilized and a fertilized egg cell developed into a 4-cell embryo. However, a pregnancy was not achieved.22
Physiological conditions are restored with retransplantation in the adnexal space, so a pregnancy occurring spontaneously is possible. This option has been performed successfully in adult women and 10 known pregnancies after re-transplantation are mentioned in the literature.23 From experience in adults, it has been shown that ovarian function can be re-established up to a certain extent after transplantation of ovarian tissue. However, the efficacy of using cryoconserved ovarian tissue is reduced compared to the use of “fresh” non-cryoconserved tissue.24 In monozygotic twins, discordant for premature ovarian failure, transplantation of heterologous “fresh” ovarian tissue led to successful pregnancies.25 Proof of long-term efficacy and life expectancy of the ovarian transplant is not yet available. An important point that must be discussed is the risk of re-transplanting malignant cells with the ovarian tissue. Excluding of the presence of malignant cells in the ovarian tissue could be performed using histological techniques; however, on a cautionary note, only a small and therefore doubtfully representative tissue sample can be examined. In patients with Hodgkin’s disease, it appears to be certain that there is no risk of contamination of the removed ovarian tissue with malignant cells.26 An exception is Burkitt’s lymphoma.27 According to current data, ovarian tissue cannot be retransplanted in patients with leukemia because of the systemic nature of the disease. Ovarian tissue could only be removed and cryoconserved in this situation in the hope that in vitro maturation of the oocytes will be possible in the future. Several study groups have reported on ovarian tissue removal on girls and adolescents,19,23,28,29 although only in Poirot’s study group,29 the mean age was 6.1 years. The mean age of the young patients treated in the other groups mentioned was between 10.423 and 13.5 years.28 None of the study groups described complications occurring as part of the ovarian tissue removal process. A maximum of 5 days elapsed between ovarian tissue removal and the start of chemotherapy in the oncology patients.23 Up to now, there are no reports about re-transplantation of ovarian tissue which was removed before puberty. Admittedly, this technique was only developed during the last decade, and the report on the first retransplantation of cryoconserved ovarian tissue is from the year 2000.30 Patients who had ovarian tissue removed before puberty or during adolescence are usually still too young to enquire about re-transplantation of the tissue. Over the next few years, significant experience is expected to be gained in the field of cryoconservation and retransplantation. Ovarian Transposition
The aim of ovarian transposition before planned pelvic radiotherapy or the caudal spine is to relocate the ovaries away from the radiation field and therefore to reduce the radiation dosage reaching the ovaries. One or both of the ovaries are transposed either behind the uterus,
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craniolaterally or under the diaphragm. Scattered radiation can reduce the effectiveness of this technique. There is controversial data on the efficacy of ovarian transposition in the literature: Terenziani et al31 reported on 14 pregnancies with 12 live births in 11 women suffering from Hodgkin’s disease. The mean age at diagnosis and performance of this technique was 13 years (range 9e22 years), and the patients underwent retro-uterine ovarian transposition as part of a staging laparotomy between 1972 and 1988. A current review32 found the incidence of POI to be 50e90% after ovarian transposition. Alongside the risk of the surgical procedure itself, there is a danger of disturbed blood flow with tube infarction, the development of ovarian cysts and chronic pain after craniolateral transposition of the ovaries.33 To naturally achieve a pregnancy at a later date, a further surgical procedure is necessary to relocate the ovaries. Without relocation, extracorporeal fertilization must be performed. Treatment monitoring and especially egg cell collection would be much more difficult because of the cranial positioning of the ovaries. As a combination of radiotherapy and chemotherapy can have a negative effect on the ovarian reserve because of the substances used, ovarian transposition should be very critically considered in this situation. Counselling Situation
The possibility of a child becoming a mother at a later date has a low priority in girls with oncological disease compared to the worries about them surviving. Nevertheless, the effects of cancer treatment on the reproductive function and later fertility should be discussed with the patients and their families before the start of treatment. Anderson et al34 investigated the approach to counselling on the effects of chemotherapy and/or radiotherapy on fertility: while the negative effect of treatment on the ovarian function was discussed with 86% of the postpubertal girls and their parents, it was discussed only with 60% of the prepubertal girls. The most common reason for not discussing this was that no significant risk of developing infertility was seen (79%). Nevertheless, the study showed that there is a high sensitivity to this subject by the pediatric oncologists. This was also confirmed in another study.35 However, 64% of the oncologists had difficulty in finding a suitable information center regarding to fertility preservation methods. The FertiPROTEKT network was founded in Germany in 2006, with the aim of counselling patients before chemotherapy, and the performance of fertility preservation techniques including recording and scientifically evaluating the data.36 In 2007, the Task Force of the European Society of Human Reproduction and Embryology “Fertility preservation in severe diseases” was established (www.eshre.eu). The Task Force involves specialists from all areas of reproductive medicine, reproductive biology and psychology and focuses on the publication of review articles on different topics of fertility preservation and the organization of workshops. In addition, the American Society for Reproductive Medicine established the Fertility Preservation
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Special Interest Group to promote knowledge among health care workers and the public on infertility induced by cancer therapy (www.asrm.org). Ethical Considerations
The aim of fertility preservation methods is to protect ovarian function from the negative effects of cytotoxic treatments or radiotherapy. The only established technique up to now is the cryoconservation of fertilized egg cells or embryos, depending on the legislation of the respective countries. This technique cannot be used in prepubertal girls because of their sexual immaturity. All other methods can only be regarded as experimental at the moment.37 Up to the age 18 or—depending on the law—age 21, children are not able to or only partly able to give consent. Considering their age, it can be assumed that prepubertal girls cannot understand the significance of a possible loss of fertility and the meaning of fertility preservation methods. The parents must therefore decide, and assume the possible future wishes of the girl. A decision for or against fertility preservation methods can only be made by the oncologists, specialists in reproductive medicine, the parents, and wherever possible, the young patient who is affected after comprehensive counselling on the prospects and risks of each technique in relation to the risk of the risk of loss of fertility. Acknowledgment
We are greatly indebted to Mrs. Elizabeth Kraemer for reviewing our manuscript. References 1. Gesundheitsberichterstattung des Bundes, Robert-Koch-Institut: Krebs in € €ufigkeiten und Trends 2008;6. Uberarbeitete Deutschland 2003 e 2004. Ha Auflage:102 2. Jemal A, Siegel R, Xu J, et al: Cancer Statistics, 2010. CA Cancer J Clin 2010; 60: 277 3. Ries LA, Eisner MP, Kosary CL, et al: SEER cancer statistics review, 1973 e 1998. Bethesda, MD, National Cancer Institute, 2001 4. Lawrenz B, Jauckus J, Kupka M, et al: Fertility preservation in O 1000 patients: patient’s characteristics, spectrum, efficacy and risks of applied preservation techniques. Arch Gynecol Obstet 2011; 283:651 5. Sklar CA, Mertens AC, Mitby P, et al: Premature menopause in survivors of childhood cancer: a report from the childhood cancer survivor study. J Natl Cancer Inst 2006; 98:890 6. Byrne J, Fears TR, Gail MH, et al: Early menopause in long-term survivors of cancer during adolescence. Am J Obstet Gynecol 1992; 166:788 7. Chabbert Buffet N, Djakoure C, Maitre SC, et al: Regulation of the human menstrual cycle. Front Neuroendocrinol 1998; 19:151 8. Faddy MJ, Gosden RG, Gougeon A, et al: Accelerated disappearance of ovarian follicles in mid-life: implications for forecasting menopause. Hum Reprod 1992; 7:1342 9. Warne GL, Fairley KF, Hobbs JB, et al: Cyclophosphamide induced ovarian failure. N Engl J Med 1973; 289:1159 10. Sonmezer M, Oktay K: Fertility preservation in female patients. Hum Reprod Update 2004; 10:251 11. Meirow D, Lewis H, Nugent D, et al: Subclinical depletion of primordial follicular reserve in mice treated with cyclophosphamide: clinical importance and proposed accurate investigative tool. Hum Reprod 1999; 14:1903 12. Meirow D: Reproduction post-chemotherapy in young cancer patients. Mol Cell Endocrinol 2000; 169:123 13. Wallace WH, Shalet SM, Hendry JH, et al: Ovarian failure following abdominal irradiation in childhood: the radiosensitivity of the human oocyte. Br J Radiol 1989; 62:995 14. Sanders JE, Hawley J, Levy W, et al: Pregnancies following high-dose cyclophosphamide with or without high-dose busulfan or total-body irradiation and bone marrow transplantation. Blood 1996; 87:3045
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B. Lawrenz et al. / J Pediatr Adolesc Gynecol 25 (2012) 284e288
15. Wallace WH, Thomson AB, Saran F, et al: Predicting age of ovarian failure after radiation to a field that includes the ovaries. Int J Radiat Oncol Biol Phy 2005; 62:738 16. Bath LE, Wallace WH, Critchley HO: Late effects of the treatment of childhood cancer on the female reproductive system and the potential for fertility preservation. BJOG 2002; 109:107 17. Littley MD, Shalet SM, Beardwell CG, et al: Radiation-induced hypopituitarism is dose-dependent. Clin Endocrinol 1989; 31:363 18. Wallace WH, Anderson RA, Irvine DS: Fertility preservation for young patients with cancer: who is at risk and what can be offered? Lancet Oncol 2005; 6: 209 19. Schmidt KT, Larsen EC, Andersen CY, et al: Risk of ovarian failure and fertility preserving methods in girls and adolescents with a malignant disease. BJOG 2010; 117:163 20. O’Brien MJ, Pendola JK, Eppig JJ: A revised protocol for in vitro development of mouse oocytes from primordial follicles dramatically improves their developmental competence. Biol Reprod 2003; 68:1682 21. Smitz J, Dolmans MM, Donnez J, et al: Current achievement and future research directions in ovarian tissue culture, in vitro follicle development and transplantation: implications for fertility preservation. Hum Reprod Update 2010; 16:395 22. Oktay K, Buyuk E, Veeck L, et al: Embryo development after heterotopic transplantation of cryopreserved ovarian tissue. Lancet 2004; 363:837 23. Jadoul P, Dolmans MM, Donnez J: Fertility preservation in girls during childhood: is it feasible, efficient and safe and to whom should it be proposed? Hum Reprod Update 2010; 16:617 24. Bedaiwy MA, El-Nashar SA, El Saman AM, et al: Reproductive outcome after transplantation of ovarian tissue: a systematic review. Hum Reprod 2008; 23: 2709 25. Silber SJ, DeRosa M, Pineda J, et al: A series of monozygotic twins discordant for ovarian failure: ovary transplantation (cortical versus microvascular) and cryopreservation. Hum Reprod 2008; 23:1531
26. Kim SS, Radford J, Harris M, et al: Ovarian tissue harvested from lymphoma patients to preserve fertility may be safe for autotransplantation. Hum Reprod 2001; 16:2056 27. Osborne B, Robboy SJ: Lymphomas or leukemia presenting as ovarian tumors. An analysis of 42 cases. Cancer 1983; 52:1933 28. Feigin E, Abir R, Fisch B, et al: Laparoscopic ovarian tissue preservation in young patients at risk for ovarian failure as a result of chemotherapy/irradiation for primary malignancy. J Pediatr Surg 2007; 42:862 res L, Genestie C, et al: [Ovarian tissue cryopreservation for 29. Poirot C, Brugie prepubertal girls: indications and feasibility]. [Article in French] Gynecol Obstet Fertil 2005; 33:799 30. Oktay K, Karlikaya G: Ovarian function after transplantation of frozen, banked autologous ovarian tissue. N Engl J Med 2000; 342:1919 31. Terenziani M, Piva L, Meazza C, et al: Oophoropexy: a relevant role in preservation of ovarian function after pelvic irradiation. Fertil Steril 2009; 91: 935.e15 32. Wo JY, Viswanathan AN: Impact of radiotherapy on fertility, pregnancy, and neonatal outcomes in female cancer patients. Int J Radiat Oncol Biol Phys 2009; 73:1304 33. Meirow D, Nugent D: The effects of radiotherapy and chemotherapy on female reproduction. Hum Reprod Update 2001; 7:535 34. Anderson RA, Weddell A, Spoudeas HA, et al: Do doctors discuss fertility issues before they treat young patients with cancer? Hum Reprod 2008; 23:2246 35. Goodwin T, Elizabeth Oosterhuis B, Kiernan M, et al: Attitudes and practices of pediatric oncology providers regarding fertility issues. Pediatr Blood Cancer 2007; 48:80 € r fertilita €tsprotektive 36. Lawrenz B, von Wolff M: FertiPROTEKT e Netzwerk fu € r Reproduktionsmedizin Maßnahmen bei Chemo- und Strahlentherapie. Journal fu und Endokrinologie 2010; 7:147 37. Lee SJ, Schover L, Partridge AH, et al: American Society of Clinical Oncology recommendations on fertility preservation in cancer patients. J Clin Oncol 2006; 24:2917