Purpose Population-based studies have established a link between race and prostate cancer (PC) risk, but whether race predicts PC after adjusting for clinical characteristics is unclear. We investigated the association between race and risk of low- and high-grade PC in men undergoing initial prostate biopsy in an equal access medical center. Methods We conducted a retrospective record review of 887 men (48.6 % black, 51.4 % white) from the Durham Veterans Affairs Medical Center who underwent initial prostate biopsy between 2001 and 2009. Multivariable logistic regression analysis of race and biopsy outcome was conducted adjusting for age, body mass index, number of cores taken, prostate-specific antigen (PSA), and digital rectal examination findings. Multinomial logistic regression was used to test the association between black race and PC grade (Gleason <7 vs. ≥7). Results Black men were younger at biopsy (61 vs. 65 years, p <0.001) and had a higher pre-biopsy PSA (6.6 vs. 5.8 ng/ml, p = 0.001). A total of 499 men had PC on biopsy (245 low grade; 254 high grade). In multivariable analyses, black race was significantly predictive of PC overall [odds ratio 1.50, p = 0.006] and high-grade PC [relative risk ratio (RRR) 1.84, p = 0.001], but was not significantly associated with low-grade PC (RRR 1.29, p = 0.139). Conclusion In an equal access healthcare facility, black race was associated with greater risk of PC detection on initial biopsy and of high-grade PC after adjusting for clinical characteristics. Additional investigation of mechanisms linking black race and PC risk and PC aggressiveness is needed.

Aims: Uridine diphosphate-glucuronosyltransferase 2B (UGT2B) enzymes conjugate testosterone metabolites to enable their excretion in humans. The functional significance of the UGT2B genetic variants has never been described in humans. We evaluated UGT2B variants in relation to plasma androstane-3a,17b-diol-glucuronide (AAG) levels and the prostate cancer risk. Results: AAG levels were measured in sera from 150 controls and compared to the polymorphisms of UGT2B17, UGT2B15, and UGT2B7. Genomic DNA from controls (301) and cases (148) was genotyped for the polymorphisms, and odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression analyses. Having two copies of UGT2B17 was associated with higher AAG levels in controls among Whites ( p = 0.02), but not Blacks ( p = 0.82). Logistic regression models adjusting for age and race revealed that homozygosity for the G allele of the UGT2B15 D85Y polymorphism was directly associated with the prostate cancer risk (OR = 2.70, 95% CI = 1.28, 5.55). Conclusions: While the small sample size limits inference, our findings suggest that an association between the UGT2B17 copy number variant (CNV) and serum AAG levels in Whites, but unexpectedly not in Blacks. This novel observation suggests that genetic determinants of AAG levels in Blacks are unrelated to the UGT2B17 CNV. This study replicates the results that show an association of UGT215 D85Y with an increased prostate cancer risk.

The role of metformin in prostate cancer chemoprevention remains unclear. REDUCE, which followed biopsy-negative men with protocol-dictated PSA-independent biopsies at 2- and 4-years, provides an opportunity to evaluate the link between metformin use and prostate cancer diagnosis with minimal confounding from screening biases. In diabetic men from REDUCE, we tested the association between metformin use, use of other anti-diabetic medications, vs. no anti-diabetic medication use and prostate cancer diagnosis as well as prostate cancer grade (low-grade Gleason 4–6, high-grade Gleason 7–10) using logistic regression. Of the 540 diabetic men with complete data, 205 (38%) did not report use of any anti-diabetic medications, 141 (26%) reported use of at least one anti-diabetic medication other than metformin, and 194 (36%) reported use of metformin. During the 4-year study, 122 men (23%) were diagnosed with prostate cancer. After adjusting for various clinical and demographic characteristics, we found that metformin use was not significantly associated with total (OR=1.19, p=0.50), low- (OR=1.01, p=0.96), or high-grade (OR=1.83, p=0.19) prostate cancer diagnosis. Likewise, there was no significant association between the use of non-metformin anti-diabetic medications and prostate cancer risk in both crude (OR=1.02, p=0.95) and multivariable analysis (OR=0.85, p=0.56). Furthermore, the interactions between anti-diabetic medication use and BMI, geographic location, coronary artery disease, smoking, and treatment group were not significant (all p>0.05). Among diabetic men with a negative pre-study biopsy who all underwent biopsies largely independent of PSA, metformin use was not associated with reduced risk of prostate cancer diagnosis.

Prostate cancer (PC) is the second leading cause of cancer death in men. Recent reports suggest that excess of nutrients involved in the one-carbon metabolism pathway increases PC risk; however, empirical data are lacking. Veteran American men (272 controls and 144 PC cases) who attended the Durham Veteran American Medical Center between 2004–2009 were enrolled into a case-control study. Intake of folate, vitamin B12, B6, and methionine were measured using a food frequency questionnaire. Regression models were used to evaluate the association among one-carbon cycle nutrients, MTHFR genetic variants, and prostate cancer. Higher dietary methionine intake was associated with PC risk (OR = 2.1; 95%CI 1.1–3.9) The risk was most pronounced in men with Gleason sum <7 (OR = 2.75; 95%CI 1.32– 5.73). The association of higher methionine intake and PC risk was only apparent in men who carried at least one MTHFR A1298C allele (OR = 6.7; 95%CI = 1.6–27.8), compared to MTHFR A1298A noncarrier men (OR = 0.9; 95%CI = 0.24–3.92) (p-interaction = 0.045). There was no evidence for associations between B vitamins (folate, B12, and B6) and PC risk. Our results suggest that carrying the MTHFR A1298C variants modifies the association between high methionine intake and PC risk. Larger studies are required to validate these findings.