BACKGROUND:

Fish and seafood n-3 fatty acids may prevent or delay the progression of prostate cancer, but epidemiologic studies do not uniformly support this hypothesis.

OBJECTIVE:

We examined the relation of fish and seafood n-3 fatty acid intakes with prostate cancer incidence and mortality.

DESIGN:

We conducted a prospective cohort study among 20,167 men participating in the Physician's Health Study who were free of cancer in 1983.

RESULTS:

During 382 144 person-years of follow-up, 2161 men were diagnosed with prostate cancer and 230 died of prostate cancer. Fish intake was unrelated to prostate cancer incidence. Survival analysis among the men diagnosed with prostate cancer revealed that those consuming fish >or=5 times/wk had a 48% lower risk of prostate cancer death than did men consuming fish less than once weekly [relative risk (RR) = 0.52; 95% CI: 0.30, 0.91; P for trend = 0.05]. A similar association was found between seafood n-3 fatty acid intake and prostate cancer mortality (RR(Q5 versus Q1) = 0.64; 95% CI: 0.42, 0.99; P for trend = 0.02). These associations became stronger when the analyses were restricted to clinically detected cases.

CONCLUSION:

These results suggest that fish intake is unrelated to prostate cancer incidence but may improve prostate cancer survival.