While many studies examine diet and prostate cancer (PCa) risk, few have assessed whether diet could influence prostate cancer-specific survival. Dietary factors that modulate the inflammatory response may alter clinical outcome, as chronic systemic inflammation may enhance PCa progression. As such, dietary zinc and fatty acids affecting the inflammatory response are promising targets for secondary prevention to impact survival after diagnosis.

We studied intake of dietary zinc and fatty acids in relation to cancer survival within the Örebro Swedish Cohort, including 525 confirmed PCa cases living in Örebro County who were diagnosed from 1989 to 1991. At the time of diagnosis, dietary data was collected by food frequency questionnaire specific to the Swedish diet. Use of dietary supplements was negligible in this population, which was assembled before the introduction of PSA testing. We studied intake of zinc and fatty acids (quartiles) and time to death (all cause and PCa-specific through Februrary 2009) using Cox proportional hazards models adjusted for lifestyle and clinical factors. Analyses were also stratified by clinical stage at diagnosis (early: T0-T2/M0, and advanced: T3-T4/M0/M1).

During follow-up, 218 men died from PCa and 257 from other causes. Zinc was not significantly associated with overall PCa-specific mortality, total mortality or in men diagnosed at an advanced stage. Yet among those diagnosed at an early stage, men with the highest zinc intake were 74% less likely to die of PCa (95% CI:0.10-0.68, ptrend=0.005) compared to lowest. High versus low intake of marine omega-3 docosahexaenoic acid (DHA) was associated with a reduced risk of PCa mortality overall (OR: 0.70, 95% CI: 0.47-1.03, ptrend=0.26), particularly among men diagnosed at an early stage (OR: 0.55, 95% CI: 0.23-1.58). DHA was not associated with death from other causes (OR: 1.07, 95% CI: 0.74-1.55, ptrend=0.68). The highest quartiles of saturated (HR: 1.15, 95% CI: 0.78-1.69), monounsaturated (HR: 1.18, 95% CI: 0.80-1.75) and polyunsaturated (HR: 0.90, 95% CI: 0.62-1.31) fatty acids were not associated with PCa survival.

Our results suggest men diagnosed at early stage prostate cancer may be sensitive to dietary zinc levels, which may prolong disease-specific survival. Omega-3 DHA may also be beneficial against prostate cancer-specific mortality, with inflammation being a potential common mechanism. Further research is needed to confirm these findings.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5747.