Abstract B107: A pooled analysis of 14 prospective cohort studies on the association between red meat, poultry, fish, and egg intake and risk of prostate cancer

Abstract

Abstract Background: Findings from epidemiological studies that have examined the association between intakes of red meat, poultry, fish and eggs and prostate cancer risk are inconsistent. Methods: We examined the associations of these dietary factors with risk of prostate cancer in an international collaboration of 14 cohort studies. The primary data from each study were analyzed using standardized criteria for the exposure and outcome variables. During the follow-up ranging from up to 10 to 22 years across studies, 51,896 incident prostate cancer cases were identified among 806,969 participants. Of these, 5,061 cases were advanced stage cases (equivalent to T4, N1 or M1 or fatal). The majority of advanced cases (n=3,692) were fatal cases. There were 37,006 low-grade cases (defined as Gleason score <8 or well/moderately differentiated) and 9,414 high-grade cases (Gleason score>=8 or poorly differentiated/ undifferentiated). A Cox proportional hazard model was used to calculate multivariate study-specific relative risks (RR) and then these results were pooled employing a random effects model. Results: Higher unprocessed red meat and processed meat intakes were not associated with a substantially increased risk of prostate cancer regardless of stage or grade, e.g. pooled RR (95% confidence interval (CI)) for advanced cancers when comparing highest versus lowest category was 0.96 (0.77–1.19) for unprocessed red meat and 1.05 (0.91–1.20) for processed meat intake. Poultry and egg intakes were not associated with risk of localized, low-grade or high-grade cancers. However, higher poultry intake was associated with a non-significant 16% decreased risk of advanced cancer when comparing the highest (≥40 g/day, equivalent to ≥1.4 ounces/day) with the lowest intake category (<5 g/day, equivalent to <0.18 ounces/day) (pooled RR, 95% CI: 0.84, 0.70–1.00, p-value test for common effects, localized vs. advanced: 0.009). Associations for poultry intake were slightly stronger and statistically significant for fatal cancers (pooled RR, 95% CI: 0.74, 0.62–0.88). Participants in the highest category of egg intake (≥25 g/day, equivalent to at least half an egg per day) had a 14% increased risk of advanced cancers when compared to participants in the lowest intake category (<5 g/day) (pooled RR, 95% CI: 1.14, 1.03–1.26, p-value test for common effects, localized vs. advanced: <0.001). However, the positive association between egg intake and risk of advanced prostate cancer was restricted to studies in North America (≥ 25g/day vs. <5 g/day: pooled RR, 95% CI: 1.23, 1.10–1.37) whereas egg intake was not associated with risk of advanced cancer in studies in other continents (pooled RR, 95% CI: 0.95, 0.79–1.14). Intake of seafood (i.e. fish and other types of seafood including shellfish) was not associated with risk of prostate cancer regardless of stage and grade. Conclusion: Our results do not support a substantial association between unprocessed red meat, processed meat or seafood intake and risk of prostate cancer regardless of stage or grade. Higher poultry intake was associated with a modest decreased risk of fatal prostate cancer. The positive association between egg intake and risk of advanced cancers warrants further investigation given the observed differences in associations by geographical region. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B107.