Association of vitamin D receptor and 17 hydroxylase gene polymorphisms with benign prostatic hyperplasia and benign prostatic enlargement

BASIC SCIENCE CME ARTICLE

ASSOCIATION OF VITAMIN D RECEPTOR AND 17 HYDROXYLASE GENE POLYMORPHISMS WITH BENIGN PROSTATIC HYPERPLASIA AND BENIGN PROSTATIC ENLARGEMENT GEORG SCHATZL, ANDREA GSUR, GABRIELE BERNHOFER, GERALD HAIDINGER, SONJA HINTEREGGER, CHRISTIAN VUTUC, ANDREA HAITEL, MICHAEL MICKSCHE, MICHAEL MARBERGER, AND STEPHAN MADERSBACHER

ABSTRACT Objectives. To determine whether polymorphisms in 17 hydroxylase (CYP17) and vitamin D receptor (VDR) genes have an association to prostate volume/histology and endocrine patterns in elderly men with lower urinary tract symptoms (LUTS). Methods. Elderly men with LUTS underwent the following investigations: International Prostate Symptom Score (IPSS), uroflowmetry, serum prostate-specific antigen (PSA) assessment of prostate volume, and an endocrine study. Polymorphisms of CYP17 (T3C substitution in the 5⬘ promoter region) and VDR (T1055C) genes were detected by polymerase chain reaction followed by restriction-length polymorphism analysis, using DNA from peripheral white blood cells. Clinical and endocrine parameters and the prostate stroma/ epithelial ratio were correlated to CYP17 and VDR genotypes. Results. A total of 148 (mean ⫾ SD, 67.0 ⫾ 9.7 years) patients were analyzed. IPSS (17.8 ⫾ 7.0), prostate volume (41.9 ⫾ 17.9 cc), maximum flow rate (10.9 ⫾ 5.8 mL/s), and PSA (4.7 ⫾ 4.7 ng/mL) indicate a typical LUTS population. Mean endocrine levels were consistently within age-specific reference values. Neither CYP17 nor VDR gene polymorphisms revealed an association to prostate size, PSA, clinical parameters, and endocrine parameters. Men who had the A1/A1 CYP17 genotype had on average a greater stromal/epithelial ratio than men with the A1/A2 or A2/A2 genotypes, yet after adjusting for multiple testing, this significance disappeared. Conclusions. Gene polymorphisms of CYP17 and VDR have no association to prostate volume, clinical parameters, and endocrine parameters in elderly men. The association of CYP17 polymorphism and prostate histology warrants further studies. Assessment of gene polymorphisms might provide new insights into the pathogenesis of benign prostatic hyperplasia and benign prostate enlargement and may hold promise as genetic biomarkers of this disease. UROLOGY 57: 567–572, 2001. © 2001, Elsevier Science Inc.

B

enign prostatic hyperplasia (BPH) is the most common benign tumor in aging men.1 In parallel to BPH, the prevalence of an enlarged prostate (benign prostatic enlargement [BPE]) as well as the percentage of individuals with lower urinary From the Department of Urology; Divisions of Applied and Experimental Oncology and Epidemiology, Institute of Cancer Research; Department of Clinical Pathology, University of Vienna, Vienna, Austria Reprint requests: Stephan Madersbacher, M.D., Department of Urology, University of Vienna, Wa¨hringer Gu¨rtel 18-20, A-1090 Vienna, Austria Submitted: July 10, 2000, accepted (with revisions): October 4, 2000 © 2001, ELSEVIER SCIENCE INC. ALL RIGHTS RESERVED

tract symptoms (LUTS) because of BPH/BPE increases with age.1,2 Several population-based and large-scale cross-sectional studies demonstrated that up to 20% to 40% of men in their seventh and eighth decade of life have moderate or severe LUTS.2 Despite its high prevalence and socioeconomic implications, the pathogenesis of BPH/BPE is not fully elucidated, yet the relevance of androgenic steroid hormones is established. Men castrated before puberty, such as individuals with an inherited deficiency of 5 alpha-reductase, have only a vestigial prostate. Clinical experience with finasteride has documented the relevance of dihydrotestoster0090-4295/01/$20.00 PII S0090-4295(00)01004-9 567

one on prostate size. Despite these data, the majority of studies failed to demonstrate an association between serum androgen levels and prostate volume in elderly men.3–5 Schatzl et al.5 have shown that estradiol was the only sex steroid hormone to correlate with prostate volume. Gann et al.6 found a strong correlation for increasing risk and serum estrogens. Testosterone is synthesised from cholesterol by a series of enzymatic reactions, involving several of the cytochrome P450 enzymes.7 Of interest is the cytochrome p450c17 (17 hydroxylase [CYP17]), which is the rate-limiting step in androgen biosynthesis and catalyzes two sequential reactions in the steroid biosynthesis pathway. A polymorphism in the 5⬘ promoter region within the CYP17 gene has attracted considerable interest as a biomarker for breast cancer. Recently Lunn et al.8 and Gsur et al.9 have shown that individuals with the A2/A2 allele are at higher risk for prostate cancer.10 –12 Besides adrenal and gonadal sex steroids, the steroid hormone superfamily additionally comprises vitamin D.13 There are several lines of evidence suggesting a potential role of vitamin D for the development of BPH/BPE, as the activated form of vitamin D, vitamin D3, and some of its analogues have been described as potent regulators of cell growth and differentiation.14 –16 The association between vitamin D and prostate cancer was first proposed by Schwartz et al.17 and further by Hanchette et al.,18 who first described a connection between exposure to ultraviolet light and prostate cancer mortality in the United States. In parallel to CYP17, gene polymorphisms of the vitamin D receptor (VDR) have been associated with the risk for prostate cancer.19 –21 This association, however, was not confirmed by others.22,23 Although cellular origins of BPH and prostate cancer are different, both diseases may have common risk factors and may be under comparable genetic control. The above-mentioned studies prompted us to determine the association between CYP-17 and VDR genetic polymorphisms and prostate volume, PSA, endocrine parameters, and the stroma/epithelial (S/E) ratio in elderly men. The rationale for analyzing the S/E ratio was to investigate whether polymorphism of genes involved in androgen metabolism affect the histologic composition of the prostate. MATERIAL AND METHODS STUDY POPULATION The Department of Urology and the Institute of Cancer Research of the University of Vienna are currently conducting a case-control study primarily set up to identify genetic biomarkers and lifestyle factors for the development of prostate cancer.12 The human subject protocol for this study was approved by the ethics committee of the University of Vienna. All included subjects gave written, informed consent. 568

As a control population, we have studied elderly men (white) with untreated LUTS because of BPH/BPE. This control population underwent the following investigations: International Prostate Symptom Score (IPSS), including the quality of life question (IPSS-Q1); a digital rectal examination (DRE); a free uroflow study; postvoid residual volume measurement by transabdominal ultrasonography, determination of prostate size by transrectal ultrasonography; and a serum prostatespecific antigen (PSA) determination (equimolar AxSYM PSA assay, Abbott Laboratories, Chicago, Ill). Principal inclusion criteria were an IPSS higher than 7 and aged 40 years or older. Prostate cancer was excluded clinically (negative DRE and serum PSA below age-specific reference values) or histologically by negative transrectal ultrasoundguided biopsy or negative histology, following transurethral resection of the prostate. Further exclusion criteria were (a) previous surgery of the bladder, prostate, or urethra; (b) medical therapy for LUTS by alpha1-receptor blockers, finasteride, anticholinergics; or (c) neurogenic bladder dysfunction. All controls who entered the case-control study to date (recruitment is ongoing) were analyzed; no patient was excluded. The 68 patients who underwent histologic analysis represent a subgroup of the 148 participants of this study.

ENDOCRINE STUDY Blood samples for endocrinologic and genotyping analyses were obtained by cubital vein puncture of fasting patients between 7:30 AM and 10:00 AM. The following hormones were quantified with commercially available immunoassays (the respective inter- and intra-assay coefficients of variation as given by the manufacturers are given): dehydroepiandrostendionesulphate (DHEA-S; 4.5%/2.0%; Spectrica Coated Tube Radioimmunoassay by Orion Diagnostica, Finland; normal range 0.38 to 4.13 ␮g/mL), human luteinizing hormone (LH; 4.5%/ 2.0%; normal range 1 to 9 mIU/mL), human follicle-stimulating hormone (FSH; 4.3%/3.2%; normal range 1 to 8 mIU/mL), and estradiol (5.6%/2.6%; normal range 14 to 60 pg/mL) were quantified by automated fluorescence polarization assays on AxSYM (Abbott Laboratories). Testosterone (8.9%/5.2%; normal range 2.7 to 10.7 ng/mL) was assessed by a coat-a-count radioimmunoassay (Diagnostics Products Corporation).

GENOTYPING Peripheral blood mononuclear cells (PBMCs) were isolated, using Ficoll-Paque (Amersham Pharmacia Biotech) as described by the supplier. Genomic DNA was extracted from PBMC, using QIAmp Blood Kit (Qiagen GmbH, Germany). CYP17 Gene Polymorphism. A 459-base pair (bp) fragment, containing the bp substitution, was amplified by polymerase chain reaction (PCR), using the forward primer 5⬘-CATTCGCACCTCTGGAGTC-3⬘ and the reverse primer 5⬘-GGCTTGGGGTACTTG-3⬘ described by Feigelson et al.10 All primers for PCR were obtained from Vienna Biocenter (VBC-Genomics, Austria). A total volume of 50 ␮L reaction mixture contained 200 ng DNA, PCR buffer (Perkin Elmer), 1.5 mM MgCl2 (Perkin), 200 ␮mol deoxynucleotide triphosphate (Roche Diagnostics GmbH, Austria), 10 pmol of each primer, and 1.5 U Taq Polymerase (Perkin). PCR condition was an initial denaturation step for 5 minutes at 94°C, 30 cycles at 94°C for 30 seconds, 57°C for 30 seconds, and 72°C for 30 seconds, followed by a final elongation step at 72°C for 5 minutes. The PCR products were digested for 2 hours at 37°C, using restriction enzyme MspAI (New England Biolabs MgbH, Germany) and separated on a 2% ethidium bromide-stained agarose gel. VDR Gene Polymorphism. VDR Taq genotype was determined by a PCR-based method. A 740-bp fragment was amplified, using the primers 5⬘-CAG AGC ATG GAC AGG GAG CAA and 5⬘-GCA ACT CCT CAT GGC TGA GGT CTC, described by Riggs et al.24 The PCR primers were obtained from Vienna Biocenter (VBC-Genomics). The C3 T bp substituUROLOGY 57 (3), 2001

TABLE I. Principal clinical and endocrinologic parameters of the study population (n ⴝ 148) Percentiles Parameter Clinical Age (yr) IPSS Qmax (mL/s) Prostate volume (cc) PSA (ng/mL) Endocrinologic Testosterone (ng/mL) Estradiol (pg/mL) DHEA-S (␮g/mL) LH (mIU/mL) FSH (mIU/mL) Histologic S/E ratio (n ⫽ 68)

Mean (ⴞSD)

25th

50th

75th

67.0 17.8 10.9 41.9 4.7

⫾ ⫾ ⫾ ⫾ ⫾

9.7 7.0 5.8 17.9 4.7

60 13 6.8 30 1.2

67 17 10 40 3.2

74 23 13.6 50 6.3

4.1 30.1 1.1 7.5 8.5

⫾ ⫾ ⫾ ⫾ ⫾

1.6 14.0 0.8 6.3 6.0

3.1 19 0.51 3.9 4.8

3.8 29 0.93 6.0 6.6

4.9 38 1.52 9.3 10.7

1.7

2.3

4.0

2.9 ⫾ 1.6

KEY: IPSS ⫽ International Prostate Symptom Score; Qmax ⫽ maximum flow rate; PSA ⫽ prostate-specific antigen; DHEA-S ⫽ dehydroepiandrostendionesulphate; LH ⫽ luteinizing hormone; FSH ⫽ follicle-stimulating hormone; S/E ⫽ stroma/epithelial.

tion in exon 9 leads to the loss of the TaqI restriction site. The PCR fragment was digested with the restriction enzyme TaqI and separated on a 3% ethidium bromide-stained agarose gel, which allows designation of the alleles T (TaqI site absent) and t (TaqI site present).24

HISTOLOGY

BPH tissues (n ⫽ 68) obtained by transurethral resection of the prostate (n ⫽ 61) or transrectal ultrasound-guided biopsies (n ⫽ 7) were formalin fixed and paraffin embedded. All histologic sections were stained with hematoxylin and eosin. These sections were reviewed by one pathologist (A.H.) experienced in prostate pathology who had no knowledge of the genotyping results. The S/E ratio was quantified at ⫻100 magnification. The area of glands, including the glandular lumen, was expressed as the percentage of the total area analyzed. BPH was histologically classified, according to World Health Organization criteria, as atypical adenomatous hyperplasia, and high-grade prostatic intraepithelial neoplasia was given in the case of atypia.25–28

STATISTICAL ANALYSIS Statistical procedures were calculated by the computer software SPSS (version 6.0.1 for Windows). Patients were grouped according to their CYP17 and VDR genotypes. Differences between groups regarding clinical, endocrinologic parameters, and S/E ratio were tested, using Student’s t test. To adjust for multiple testing, the methods of Bonferroni-Holm were applied. The Hardy-Weinberg equilibrium of the genetic polymorphisms was determined by the chi-square test.

RESULTS PRINCIPAL PATIENT CHARACTERISTICS Principal patient characteristics with respect to clinical and endocrinologic parameters are given in Table I. Values for IPSS (mean ⫾ SD, 17.8 ⫾ 7.0), IPSS-Q1 (3.4 ⫾ 1.5), maximum flow rate (Qmax; 10.9 ⫾ 5.8 mL/s), prostate volume (41.9 ⫾ 17.9 cc), and serum PSA (4.7 ⫾ 4.7 ng/mL) indicate a UROLOGY 57 (3), 2001

typical LUTS population seen at a referral center (Table I). In parallel, mean endocrine levels of testosterone (4.1 ⫾ 1.6 ng/mL), estradiol (30.1 ⫾ 14 pg/mL), DHEA-S (1.1 ⫾ 0.8 ␮g/mL), LH (7.5 ⫾ 6.3 mIU/mL), and FSH (8.5 ⫾ 6.0 mIU/mL) were consistently within age-specific reference values (Table I). ASSOCIATION OF CYP17/VDR GENE POLYMORPHISMS CLINICAL/ENDOCRINOLOGIC PARAMETERS CYP17 Polymorphism. A total of 52 (35.1%) patients had the wild type A1/A1 genotype, which was in the Hardy-Weinberg equilibrium, 81 (54.7%) the A1/A2 genotype, and 15 (10.2%) the A2/A2 genotype. We subsequently tested for differences of clinical (prostate volume/PSA) and endocrinologic (testosterone, estradiol, DHEA-S, LH, and FSH) parameters, depending on the CYP17 genotype (A1/A1 versus A1/A2 versus A2/A2). These data are given in Table II. Age did not differ in the three groups. Neither PSA level nor prostate size differed by the CYP17 genotype. Regarding serum hormone levels, no statistically significant difference was detectable for LH, FSH, testosterone, estradiol, and DHEA-S in the three CYP17 genotype groups. VDR Gene Polymorphism. VDR gene polymorphism was in the Hardy-Weinberg equilibrium in which 37.8% (n ⫽ 56) had the wild type genotype (TT), 48.6% (n ⫽ 72) the Tt haplotype, and 13.6% (n ⫽ 20) the tt genotype. We subsequently grouped clinical and endocrinologic parameters, depending on VDR genotypes (Table III). VDR gene polymorphism revealed no association to TO

569

TABLE II. Clinical and endocrinologic parameters and S/E ratio by the CYP17 gene type Parameter

Wild Type*

Clinical Age (yr) IPSS Qmax (mL/s) Prostate volume (cc) PSA (ng/mL) Endocrinologic Testosterone (ng/mL) Estradiol (pg/mL) DHEA-S (␮g/mL) LH (mIU/mL) FSH (mIU/mL) Histologic S/E ratio (n ⫽ 68)

(n 66.4 18.1 9.6 40.2 3.7

⫽ ⫾ ⫾ ⫾ ⫾ ⫾

54) 9.8 7.9 4.3 16.4 3.5

(n 67.7 17.2 11.4 43.5 5.3

⫽ ⫾ ⫾ ⫾ ⫾ ⫾

79) 9.9 6.2 5.5 19.7 5.1

(n 65.7 17.3 12.6 39.7 5.1

⫽ ⫾ ⫾ ⫾ ⫾ ⫾

15) 9.2 7.4 9.6 12.5 6.0

4.1 33.9 1.2 8.0 9.1

⫾ ⫾ ⫾ ⫾ ⫾

1.7 16.1 0.8 6.6 6.5

4.1 28.3 1.0 7.3 8.0

⫾ ⫾ ⫾ ⫾ ⫾

1.6 12.1 0.7 6.5 5.5

3.9 26.8 1.4 7.5 9.4

⫾ ⫾ ⫾ ⫾ ⫾

1.7 14.1 1.0 4.0 6.7

3.5 ⫾ 2.0 (n ⫽ 25)

A1/A2*

2.6 ⫾ 1.1† (n ⫽ 34)

A2/A2*

2.7 ⫾ 1.5† (n ⫽ 9)

KEY: S/E ⫽ stroma/epithelial; CYP17 ⫽ 17 hydroxylase; IPSS ⫽ International Prostate Symptom Score; Qmax ⫽ maximum flow rate; PSA ⫽ prostate-specific antigen; DHEA-S ⫽ dehydroepiandrostendionesulphate; LH ⫽ luteinizing hormone; FSH ⫽ follicle-stimulating hormone. * Numbers indicate the respective means ⫾ SD. † P ⫽ 0.03 as compared to A1/A1 genotype in Student’s t test. When adjusted for multiple testing according to the methods of Bonferroni and Holm, however, no statistical significance was calculated (P ⫽ 0.86).

TABLE III. Clinical and endocrinologic parameters and S/E ratio by VDR gene type Parameter Clinical Age (yr) IPSS Qmax (mL/s) Prostate volume (cc) PSA (ng/mL) Endocrinologic Testosterone (ng/mL) Estradiol (pg/mL) DHEA-S (␮g/mL) LH (mIU/mL) FSH (mIU/mL) Histologic S/E ratio (n ⫽ 68)

Wild Type (TT)*

Tt*

tt*

(n ⫽ 56) 66.5 ⫾ 10.1 18.3 ⫾ 7.7 11.6 ⫾ 5.9 40.2 ⫾ 16.9 4.1 ⫾ 3.5

(n ⫽ 72) 67.2 ⫾ 9.9 17.3 ⫾ 7.2 10.6 ⫾ 6.1 42.5 ⫾ 19.2 5.2 ⫾ 5.7

(n ⫽ 20) 68.1 ⫾ 8.1 17.9 ⫾ 4.1 9.8 ⫾ 3.8 44.3 ⫾ 16.2 4.8 ⫾ 4.8

4.1 30.6 1.2 7.1 8.5

⫾ ⫾ ⫾ ⫾ ⫾

2.0 14.2 0.8 5.7 5.3

3.0 ⫾ 1.7 (n ⫽ 22)

4.1 29.8 1.0 8.2 8.7

⫾ ⫾ ⫾ ⫾ ⫾

1.5 14.7 0.7 7.2 6.9

3.7 30.1 1.2 6.3 7.7

2.8 ⫾ 1.1 (n ⫽ 34)

⫾ ⫾ ⫾ ⫾ ⫾

1.1 11.4 0.8 4.0 4.4

3.0 ⫾ 2.5 (n ⫽ 12)

KEY: S/E ⫽ stroma/epithelial; VDR ⫽ vitamin D receptor; IPSS ⫽ International Prostate Symptom Score; Qmax ⫽ maximum flow rate; PSA ⫽ prostate-specific antigen; DHEA-S ⫽ dehydroepiandrostendionesulphate; LH ⫽ luteinizing hormone; FSH ⫽ follicle-stimulating hormone. * Numbers indicate the respective means ⫾ SD.

prostate size, PSA, IPSS, uroflow parameters, and hormone values. ASSOCIATION BETWEEN VDR AND CYP17 GENOTYPES AND PROSTATE HISTOLOGY In a subgroup of patients (n ⫽ 68) for whom prostate specimens were available, we correlated the S/E ratio to VDR and CYP17 genotypes. There was no correlation between VDR gene polymorphism and the S/E ratio (Table III). In contrast, the CYP17 polymorphism yielded a statistically significant association to the S/E ratio: 570

the S/E ratio was significantly higher in individuals with the A1/A1 genotype (3.4) as compared to those with A1/A2 (2.6) and A2/A2 genotypes (P ⫽ 0.03) (Table II). When adjusted for multiple testing according to the methods of Bonferroni and Holm, however, no statistical significance was calculated (P ⫽ 0.86). COMMENT The identification of genetic markers predictive for the development of BPH/BPE would be a major UROLOGY 57 (3), 2001

step toward a comprehensive understanding of the most common benign tumor in men and for the design of (chemo)preventive strategies. Of particular interest in this respect are genes involved in steroid hormone synthesis. In this study we report for the first time on the association between the CYP17 gene polymorphism and BPH/BPE; one recent study29 reported on the effect of VDR gene polymorphisms in this respect. A limitation of the current study is that we have not included a control population; therefore, we cannot directly evaluate whether the specific gene polymorphisms are important for the development of BPH/BPE/LUTS. Given the high prevalence of LUTS, BPH, and BPE in this age group, it is difficult to identify an agematched control group (eg, to exclude BPH, all controls would have to undergo prostate biopsy). The CYP17 gene maps to chromosome 10q24.3 and contains eight exons.30 –32 A T3 C transition (A2 allele) in the 5⬘ promoter region of CYP17 creates an additional Sp1-type (CCACC box) promoter site, suggesting that the A2 allele may have an increased rate of transcription that might lead to an enhanced rate of testosterone production.32 This hypothesis, however, has not been proven to date. The frequency distribution of CYP17 genotypes in our white study population was comparable to the white control group in the study by Lunn et al.,8 who reported on a case-control study regarding CYP17 polymorphism and prostate cancer risk: A1/A1, 35.1% (present study) versus 43% (North Carolina); A1/A2, 54.7% versus 46%, and 10.2% versus 11%.8 These observations indicate a high consistency regarding the CYP17 genotype pattern in white men on different continents. In our population, the CYP17 genotype had no effect on sex steroid serum hormone levels and prostate volume. In parallel to CYP17 genotypes, this study failed to demonstrate an association between a VDR gene polymorphism and a number of clinical and endocrinologic parameters and prostate volume. These data are in line with a recent publication of Bousema et al.,29 who also did not observe an effect of VDR gene polymorphisms on the risk for the development of LUTS, BPE, and benign prostatic obstruction. Obviously, VDR gene polymorphisms have a different effect on benign and malignant prostatic diseases.19 –21,29 Several VDR polymorphisms (intron 8, exon 9, and 3⬘UTR of the VDR gene) have been identified; as there is strong linkage disequilibrium with one another, we analyzed just one.33 Because of the fact that vitamin D is a member of the steroid hormone superfamily and that steroid hormone receptors share substantial homologies, it was of interest to study the effect of the VDR gene polymorphism on the endocrine status in elderly men. This attempt was also negative. In a subgroup of patients (n ⫽ 68) for whom prostate specimens were available for histologic UROLOGY 57 (3), 2001

analysis, we correlated CYP17 and VDR genotypes to the histologic composition in the human prostate and focused on the S/E ratio. The VDR gene polymorphism was not predictive for the S/E ratio. In contrast, the CYP17 polymorphism yielded a significant correlation to the S/E ratio as individuals with the A1/A2 and A2/A2 genotype had significantly lower ratios than the wild type group. After adjusting for multiple testing (Bonferroni-Holm), this significance disappeared. Nevertheless, these findings warrant further studies; for example, whether the same holds also true for other gene polymorphism involved in androgen biosynthesis or androgen receptor expression.29,34,35 CONCLUSIONS Gene polymorphisms of CYP17 and VDR have no association to prostate volume, clinical parameters, and endocrine parameters in elderly men. Individuals with the CYP17 wild type (A1/A1) genotype had a higher S/E ratio than those with A1/A2 and A2/A2 genotypes. Assessment of gene polymorphisms by PCR of PBMCs might provide new insights into the pathogenesis of BPH/BPE and, in parallel to prostate cancer, might hold promise as genetic biomarkers of this disease. REFERENCES 1. Oishi K, Boyle P, Barry MJ, et al: Epidemiology and natural history of benign prostatic hyperplasia, in Denis L, Griffiths K, Khoury S, et al (Eds): 4th International Consultation on Benign Prostatic Hyperplasia (BPH). Plymouth, United Kingdom, Health Publication Distributors Ltd, 1998, pp 25– 59. 2. Madersbacher S, Haidinger G, Temml C, et al: The prevalence of lower urinary tract symptoms in Austria as assessed by an open survey of 2096 men. Eur Urol 34: 136 –141, 1998. 3. Suzuki K, Ito K, Ichinose Y, et al: Endocrine environment of benign prostatic hyperplasia: prostate size and volume are correlated with serum estrogen concentration. Scand J Urol Nephrol 29: 65– 68, 1995. 4. Lagiouo P, Mantzoros CS, Tzonou A, et al: Serum steroids in relation to benign prostatic hyperplasia. Oncology 54: 497–501, 1997. 5. Schatzl G, Bro¨ssner C, Schmid S, et al: Endocrine status in elderly men with lower urinary tract symptoms: correlation of age, hormonal status and lower urinary tract function. Urology 55: 397– 402, 2000. 6. Gann PH, Hennekens CH, Longcope C, et al: A prospective study of plasma hormone levels, nonhormonal factors, and development of benign prostatic hyperplasia. Prostate 26: 40 – 49, 1995. 7. Waterman MR, and Keeney DS: Genes involved in androgen biosynthesis and the male phenotype. Horm Res 38: 217–221, 1992. 8. Lunn RM, Bell DA, Mohler JL, et al: Prostate cancer risk and polymorphism in 17 hydroxylase (CYP17) and steroid reductase (SRD5A2). Carcinogenesis 20: 1727–1731, 1999. 9. Gsur A, Bernhofer G, Hinteregger S, et al: A polymorphism in the CYP17 gene is associated with prostate cancer. Int J Cancer 87: 434 – 437, 2000. 10. Bergmann-Jungstrom M, Gentile M, Lundin AC, et al: As571

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UROLOGY 57 (3), 2001