Abstract A90: Fish intake and prostate cancer risk: Results from a multiethnic case-control study

Background: The role of diets high in fish and prostate cancer (PCa) risk is unclear. Whereas studies from Japan and Sweden have reported positive associations, others have reported protective effects. These inconsistencies might be explained by lack of consideration of the type of fish (dark vs. white) and by racial/ethnic differences in study populations. Few studies have included African-American men, who have the highest incidence of PCa.

Methods: We used data from the California Collaborative Case-Control Study of Prostate Cancer, a multi-ethnic population-based study of 1949 cases (1195 advanced and 754 localized PCa cases) and 1135 controls, which included 25%African Americans. We considered intake of white fish (flounder, halibut, snapper, bass, cod, sole), dark fish (salmon, mackerel, cat fish, trout, herring, sardines, etc.), fried fish and tuna fish. We used conditional logistic regression analysis to estimate odds ratios (OR) and 95% confidence intervals (CI), adjusting for age, PCa family history, body mass index, caloric intake, vitamin D and total fat.

Results: Consumption of white fish (highest vs. lowest quartile) was associated with increased PCa risk (OR = 1.7; 95% CI = 1.2–2.5). OR estimates did not differ by stage (localized vs advanced) or race (African Americans vs Caucasians or Hispanics). Dark fish consumption was not associated with risk. Consumption of fried fish (highest vs. lowest quartile) was associated with increased risk only among whites and Hispanics (OR = 2.4; 95% CI = 1.2–4.9) but not African Americans. Among whites and Hispanics, this effect was stronger for localized PCa (OR 3.2; 95% CI = 1.4–7.4), than advanced PCa (OR = 2.0; 95% CI = 0.9–4.3). When taking into account cooking methods, we found that the positive association between high intake of white fish and PCa risk was restricted to subjects who usually cooked fish using high temperature methods, such as pan-frying, oven broiling, or grilling, but not baking or other methods. Moreover, the effect of high intake of white fish was stronger among subjects who cooked the fish well done to very well done (highest vs lowest quartile OR = 3.1; 95% CI = 1.6–6.2) than among those who cooked fish just until done (OR = 1.2; 95% CI = 0.8–2.0).

Conclusions: Diets high in white fish seem to increase risk of all PCa among white, African-American, and Hispanic men, particularly when the fish is cooked using high-temperature methods and/or to very well doneness level. Diets high in fried fish seem to increase risk of localized PCa among white and Hispanic men, but not among African American men. Carcinogens that accumulate when cooking white fish at high temperatures might explain our findings. Differences in fish types used for fried fish dishes might explain the disparity we observed between white or Hispanic men versus African American men.