RE: EFFECT OF NONSTEROIDAL ANTI-INFLAMMATORY AGENTS AND FINASTERIDE ON PROSTATE CANCER RISK

0022-5347/03/1695-1798/0 THE JOURNAL OF UROLOGY® Copyright © 2003 by AMERICAN UROLOGICAL ASSOCIATION

Vol. 169, 1798 –1801, May 2003 Printed in U.S.A.

Letters to the Editor RE: COMPARING TAGUCHI AND LICH-GREGOIR URETEROVESICAL REIMPLANTATION TECHNIQUES FOR KIDNEY TRANSPLANTS F. P. Secin, A. R. Rovegno, R. E. J. Marrugat, R. Virasoro, G. A. Lautersztein and H. Ferna´ndez J Urol, 168: 926 –930, 2002 To the Editor. Although we continue to use the parallel incision extravesical ureteroneocystostomy as our primary method of ureteroneocystostomy for kidney transplants, we have had occasion to use the techniques so nicely described and illustrated by the authors.1 We believe that the incidence of significant reflux with the Lich-Gregoir technique can be decreased with the simple placement of a full thickness suture to anchor the toe of the ureter to the full thickness of the bladder.2 This application prevents the ureter from sliding within the submucosal tunnel. We have been pleased with the Taguchi technique, and use it as a secondary procedure when the bladder is small or when the mucosa is adherent to the bladder muscularis and it is difficult to develop a submucosal tunnel. The Taguchi procedure, as described in The Journal of Urology in 1968, was a stented procedure that used 2 U-stitches, 1 each on either side of the ureterotomy, rather than a single U-stitch as described by the authors. The single unstented U-stitch technique was probably first described by Schanfield in 1972.3 Respectfully, John M. Barry Division of Urology and Renal Transplantation Oregon Health and Science University 3181 SW Sam Jackson Park Rd. Portland, Oregon 97201-3098 1. Barry, J. M.: Unstented extravesical ureteroneocystostomy in kidney transplantation. J Urol, 129: 918, 1983 2. Campos-Freire Junior, G., de Goes, G. M. and de Campos-Freire, J. G.: Extravesical ureteral implantation in kidney transplantation. Urology, 3: 304, 1974 3. Schanfield, I.: New experimental methods for implantation of the ureter in bladder and conduit. Transplant Proc, 4: 637, 1972 DOI: 10.1097/01.ju.0000057801.95036.b6

RE: EFFECTS OF 5 DIFFERENT DIETS ON URINARY RISK FACTORS FOR CALCIUM OXALATE KIDNEY STONE FORMATION: EVIDENCE OF DIFFERENT RENAL HANDLING MECHANISMS IN DIFFERENT RACE GROUPS A. L. Rodgers and S. Lewandowski J Urol, 168: 931–936, 2002

a review of the literature we identified 7 articles reporting the urinary excretion of calcium and sodium in white and black subjects.1–7 While units of measurement of calcium and sodium differ from study to study (mmol./24 hours, mg./24 hours, mEq./24 hours, ␮g./mg. urinary creatinine, mg./mg. urinary creatinine, mEq./kg. body weight per 24 hours), in each study urinary calcium excretion as well as ratio of urinary calcium to urinary sodium was higher in white than in black subjects. This observation holds regardless of whether mean urinary sodium excretion in a particular study was higher or lower in white than in black subjects. It seems possible that there is a racial difference between white and black subjects in the competitive reabsorption of calcium and sodium in the renal tubules. However, the determinants of urinary calcium excretion are extremely complex, and more sophisticated testing would be required to separate a purely renal handling mechanism from a more generalized racial difference in calcium metabolism. The study of racial differences in calcium metabolism is important because it may lead to an understanding of why the incidence of urinary calculous disease and osteoporosis appears to be substantially lower in black than in white subjects.2, 5–7 Respectfully, P. R. Dodds Section of Urology Department of Surgery Norwalk Hospital Norwalk, Connecticut 06850 and J. H. Dodds Public Health Program Health Professions Division Nova Southeastern University Fort Lauderdale, Florida 33328 1. Bell, N. H., Greene, A., Epstein, S., Oexman, M. J., Shaw, S. and Shary, J.: Evidence for alteration of the vitamin D-endocrine system in blacks. J Clin Invest, 76: 470, 1985 2. Dibba, B., Prentice, A., Laskey, M. A., Stirling, D. M. and Cole, T. J.: An investigation of ethnic differences in bone mineral, hip axis length, calcium metabolism and bone turnover between West African and Caucasian adults living in the United Kingdom. Ann Hum Biol, 26: 229, 1999 3. Modlin, M.: The aetiology of renal stone: a new concept arising from studies on a stone-free population. Ann R Coll Surg Engl, 40: 155, 1967 4. O’Brien, K. O., Abrams, S. A., Stuff, J. E., Liang, L. K. and Welch, T. R.: Variables related to urinary calcium excretion in young girls. J Pediatr Gastroenterol Nutr, 23: 8, 1996 5. Pratt, J. H., Manatunga, A. K. and Peacock, M.: A comparison of the urinary excretion of bone resorptive products in white and black children. J Lab Clin Med, 127: 67, 1996 6. Whalley, N. A., Moraes, M. F., Shar, T. G., Pretorius, S. S. and Meyers, A. M.: Lithogenic risk factors in the urine of black and white subjects. Br J Urol, 82: 785, 1998 7. Widdowson, E. M. and McCance, R. A.: Use of random specimens of urine to compare dietary intakes of African and British children. Arch Dis Child, 45: 547, 1970 8. Kleeman, C. R., Bohannan, J., Bernstein, D., Ling, S. and Maxwell, M. H.: Effects of variations in sodium intake on calcium excretion in normal humans. Proc Soc Exp Biol Med, 115: 29, 1964

To the Editor. This report supports the findings of many other studies in which white subjects were noted to excrete more urinary calcium than black subjects.1–7 While not addressing the conclusion of Bell et al1 that racial differences in urinary calcium excretion are secondary to complex racial differences in vitamin D metabolism, the authors postulate that white and black subjects may have “different renal handling mechanisms” for dietary challenges. The authors do not propose a specific renal mechanism that would account for racial DOI: 10.1097/01.ju.0000060661.77701.e5 differences in calcium excretion. There is a known link between urinary calcium and sodium excretion apparently via competitive reabsorption in the renal tubules.4, 8 RE: EFFECT OF NONSTEROIDAL ANTI-INFLAMMATORY We noted that the ratio of urinary calcium to sodium was higher in AGENTS AND FINASTERIDE ON PROSTATE CANCER RISK white than in black subjects in all dietary groups in this study. This is in keeping with our own study of 96 healthy ambulatory adults on J. Irani, V. Ravery, J. L. Pariente, E. Chartier-Kastler, unrestricted diets from Norwalk, Connecticut, in which the ratio of E. Lechevallier, M. Soulie´, D. Chautard, P. Coloby, E. Fontaine, mean daily urinary calcium to sodium excretion was higher in the 78 F. Bladou, F. Desgrandchamps and O. Haillot white subjects (191.2 mg. calcium/162 mEq. sodium ⫽ 1.18) than in the 18 black subjects (69.0 mg. calcium/114 mEq. sodium ⫽ 0.61). In J Urol, 168: 1985–1988, 2002 1798

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LETTERS TO THE EDITOR To the Editor. We read with great interest this article in which the authors describe their findings of no relationship between nonsteroidal anti-inflammatory drugs and prostate cancer, and a statistically significant inverse association between finasteride use and prostate cancer. The authors went to considerable lengths to control for potential confounders in their assessments of these associations and gave thoughtful consideration to the interpretation of their findings. They also cautioned that their results should be interpreted in light of the fact that their subjects were recruited from a population that had undergone prostate biopsy at 12 different urological centers on the basis of biopsy result. While this caution is appropriate, we are concerned that it does not adequately alert readers to the problems this design aspect may have introduced. Although the investigators describe their study as population based, inclusion in the study was dependent on having an indication for a prostate biopsy, presumably an increased serum prostate specific antigen (PSA) level or an abnormal digital rectal examination. In fact, the distribution of serum PSA level was much higher in the control group than would be expected from the community at large.1 The increased serum PSA levels among men without prostate cancer are most likely due to benign prostatic hyperplasia, which would serve as an indication for treatment with a 5␣reductase inhibitor. Thus, the apparent association between finasteride and prostate cancer may solely be due to the spectrum of patients included in a biopsy series, which does not reflect the distribution of men from the community. Whether the association with finasteride would be observed in a truly representative sample of men from the community has yet to be evaluated. In a similar vein the results of the analyses of nonsteroidal antiinflammatory use and prostate cancer should be interpreted with great caution. While there is no a priori reason to expect use of these agents to be different in men with an indication for prostate biopsy compared to the general population, the concern remains a specter hanging over the potential inference. We hope that this letter will help to sensitize the urology community to the important issue of subject selection and its potential influence on the findings of observational studies.2 We applaud the attempt to ensure that the comparison group without prostate cancer is, in fact, without histological evidence of disease. Without this ascertainment, there is a potential for misclassification, most probably resulting in an estimate of association that is biased to no difference.3 However, this should not be done at any cost as the effect of misclassification is likely small but the selection factors, as present in a biopsy series, could introduce a substantial bias. Respectfully, Steven J. Jacobsen and Rosebud O. Roberts Division of Epidemiology Mayo Clinic 200 First St., SW Rochester, Minnesota 55905 1. Oesterling, J. E., Jacobsen, S. J., Chute, C. G., Guess, H. A., Girman, C. J., Panzer, L. A. et al: Serum prostate-specific antigen in a community-based population of healthy men. Establishment of age-specific reference ranges. JAMA, 270: 860, 1993 2. Jacobsen, S. J., Bergstralh, E. J., Guess, H. A., Katusic, S. K., Klee, G. G., Oesterling, J. E. et al: Predictive properties of serum-prostate-specific antigen testing in a community-based setting. Arch Intern Med, 156: 2462, 1996 3. Bross, I.: Misclassification in 2 ⫻ 2 tables. Biometrics, 10: 474, 1954 DOI: 10.1097/01.ju.0000057804.01025.13

RE: URETHRAL MOBILIZATION AND ADVANCEMENT FOR MIDSHAFT TO DISTAL HYPOSPADIAS A. Atala J Urol, 168: 1738 –1741, 2002 To the Editor. In recent decades several complex techniques have been developed to correct urethral defects. Flaps and organic or synthetic grafts have been used with significant variation in success rates. At present there is no available substitute for the male urethra that is as good as autologous urethral tissue.1 Despite the longstanding use of the extensible property of the male urethra in recon-

structive surgery, these procedures are not widely approved of by surgeons who perform urethroplasty for correction of hypospadias. The key point is how to define the mobilization limit between too much and not enough. While extensive mobilization of the male urethra may injure the urethral blood supply and spongiosclerosis or vascular erectile dysfunction may develop, a short mobilization can cause chordee and failure due to a lack of tension-free anastomosis. Guidelines in the literature about how far the male urethra can be stretched before causing penile curvature or ischemia are scarce, not only regarding anastomotic urethroplasties, but also regarding surgical procedures for hypospadias. While some authors have described a 3:1 empirical ratio (that is to bridge a 1 cm. gap 3 cm. normal urethra mobilization is recommended),2 Atala suggests that proximal mobilization of the spongy urethra to a 4:1 or 5:1 ratio is sufficient. Variations of ratios from 3:1 to 5:1 are significant and may influence the outcome of the urethral advancement procedure. Recently we presented data on urethral extensibility in fresh human cadavers.3 Considering that the proximal corpus spongiosum of patients with hypospadias is normal, we can recommend a general normal urethra-to-gap ratio of 4:1. However, age related variations of urethral extensibility should be considered. Thus, the ratio in younger patients is lower than in older patients. Respectfully, E. Alexsandro da Silva Urogenital Research Unit State University of Rio de Janeiro Av. 28 de Setembro Fundos-FCM-Terreo Rio de Janeiro, RJ 20551-030 Brazil 1. Da Silva, E. A. and Zungri Telo, E.: Urethral substitution with synthetic material. Actas Urol Esp, 24: 235, 2000 2. Hamdy, H., Awadhi, M. A. and Rasromani, K. H.: Urethral mobilization and meatal advancement: a surgical principle in hypospadias repair. Pediatr Surg Int, 15: 240, 1999 3. Da Silva, E. A. and Sampaio, F. J. B.: Urethral extensibility applied to reconstructive surgery. J Urol, 167: 2042, 2002

Reply by Authors. We would like to thank da Silva for his thoughtful comments regarding urethral mobilization for hypospadias repair. We agree that a ratio of 3:1 for urethral mobilization is insufficient and may lead to postoperative chordee. We have found that a ratio of at least 4:1 is necessary to achieve adequate urethral repair without any residual chordee. This finding is consistent with the work of da Silva in human cadavers. If a patient starts out with moderate to severe chordee, then a dissection ratio of 5:1 may be necessary. Inadequate urethral mobilization may be the reason why these procedures did not gain popularity in the past. Sufficient urethral mobilization, as well as aggressive glanular lateral dissection, allows for a successful cosmetic result. Perhaps with the advent of these new modifications and techniques urethral mobilization procedures will gain wide acceptance for hypospadias repair. Urethral mobilization and advancement for midshaft to distal defects has been our procedure of choice for the last 7 years. DOI: 10.1097/01.ju.0000057802.37619.92

RE: NITROUS OXIDE (ENTONOX) INHALATION AND TOLERANCE OF TRANSRECTAL ULTRASOUND GUIDED PROSTATE BIOPSY: A DOUBLE-BLIND RANDOMIZED CONTROLLED STUDY J. Masood, N. Shah, T. Lane, H. Andrews, P. Simpson and J. M. Barua J Urol, 168: 116 –120, 2002 To the Editor. The authors are among the many investigators finally attempting to face and deal with the pain of transrectal ultrasound guided prostate biopsy. They observed ample pain control using Entonox (50% nitrous oxide and oxygen, BOC Gases, Manchester, United Kingdom), and conclude that it should be the analgesia of choice in this setting. However, compared to periprostatic local anesthesia, Entonox has several shortcomings not fully acknowledged in the article.