Dietary calcium and risk for prostate cancer: a case-control study among US veterans.

OBJECTIVE: The objective of this study was to examine the association between calcium intake and prostate cancer risk. We hypothesized that calcium intake would be positively associated with lower risk for prostate cancer. METHODS: We used data from a case-control study conducted among veterans between 2007 and 2010 at the Durham Veterans Affairs Medical Center. The study consisted of 108 biopsy-positive prostate cancer cases, 161 biopsy-negative controls, and 237 healthy controls. We also determined whether these associations differed for blacks and whites or for low-grade (Gleason score <7) and high-grade prostate cancer (Gleason score ≥7). We administered the Harvard food frequency questionnaire to assess diet and estimate calcium intake. We used logistic regression models to obtain odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Intake of calcium from food was inversely related to risk for prostate cancer among all races in a comparison of cases and biopsy-negative controls (P = .05) and cases and healthy controls (P = .02). Total calcium was associated with lower prostate cancer risk among black men but not among white men in analyses of healthy controls. The highest tertile of calcium from food was associated with lower risk for high-grade prostate cancer in a comparison of high-grade cases and biopsy-negative controls (OR, 0.37; 95% CI, 0.15-0.90) and high-grade cases and healthy controls (OR, 0.38; 95% CI, 0.17-0.86). CONCLUSION: Calcium from food is associated with lower risk for prostate cancer, particularly among black men, and lower risk for high-grade prostate cancer among all men.

Exercise and prostate cancer risk in a cohort of veterans undergoing prostate needle biopsy.

PURPOSE: Epidemiological and molecular evidence suggest potential associations between exercise and prostate cancer risk reduction. We further characterized this relationship by examining exercise and cancer risk among men undergoing prostate needle biopsy. MATERIALS AND METHODS: A total of 190 men who underwent prostate biopsy at the Durham Veterans Affairs Medical Center completed a questionnaire on current exercise behavior. Participants were asked average frequency of mild, moderate and strenuous intensity exercise in a typical week, as well as average duration as assessed by the Godin Leisure Time Exercise Questionnaire. Total current exercise was calculated in terms of metabolic equivalent task hours per week. Primary outcome measures were prostate biopsy result and Gleason sum. RESULTS: After adjusting for age, race, body mass index, prostate specific antigen, digital rectal examination, family history, previous prostate biopsy and comorbidity score, men who reported 9 or more metabolic equivalent task hours per week of exercise were significantly less likely to have cancer on biopsy (OR 0.35, CI 0.17-0.75, p = 0.007). Furthermore, among men with malignant biopsy results, reporting moderate exercise (3 to 8.9 metabolic equivalent task hours weekly) was associated with a lower risk of high grade disease (Gleason 7 or greater, OR 0.14, CI 0.02-0.94, p = 0.04). CONCLUSIONS: To our knowledge these results provide the first evidence of an association between exercise and prostate cancer risk as well as grade at diagnosis in men scheduled to undergo prostate biopsy. Specifically moderate exercise was associated with a lower risk of prostate cancer and in men with cancer, lower grade disease. Further investigation using an objective measure of exercise in a larger sample size is required to confirm these findings.

A high ratio of dietary n-6/n-3 polyunsaturated fatty acids is associated with increased risk of prostate cancer.

Experimental studies suggest omega-3 (n-3) polyunsaturated fatty acids (PUFA) suppress and n-6 PUFA promote prostate tumor carcinogenesis. Epidemiologic evidence remains inconclusive. The objectives of this study were to examine the association between n-3 and n-6 PUFA and prostate cancer risk and determine if these associations differ by race or disease aggressiveness. We hypothesize that high intakes of n-3 and n-6 PUFA will be associated with lower and higher prostate cancer risk, respectively. A case-control study comprising 79 prostate cancer cases and 187 controls was conducted at the Durham VA Medical Center. Diet was assessed using a food frequency questionnaire. Logistic regression analyses were used to obtain odds ratios (ORs) and 95% confidence intervals (95% CI) for the associations between n-3 and n-6 PUFA intakes, the dietary ratio of n-6/n-3 fatty acids, and prostate cancer risk. Our results showed no significant associations between specific n-3 or n-6 PUFA intakes and prostate cancer risk. The highest dietary ratio of n-6/n-3 was significantly associated with elevated risk of high-grade (OR, 3.55; 95% CI, 1.18-10.69; P(trend) = 0.03), but not low-grade prostate cancer (OR, 0.95; 95% CI, 0.43-2.17). In race-specific analyses, an increasing dietary ratio of n-6/n-3 fatty acids correlated with higher prostate cancer risk among white men (P(trend) = 0.05), but not black men. In conclusion, our findings suggest that a high dietary ratio of n-6/n-3 fatty acids may increase the risk of overall prostate cancer among white men and possibly increase the risk of high-grade prostate cancer among all men.