Association between fish and shellfish consumption, n-3polyunsaturated fatty acids, and gastric cancer risk: the Japan Public Health Center-based Prospective Study.

Abstract

Fish and shellfish consumption is suggested to be a cancer-protective factor. However, studies investigating this association for gastric cancer, especially considering Helicobacter pylori (H. pylori) and atrophic gastritis (AG), are limited. We investigated gastric cancer risk associated with fish, shellfish, and n-3 polyunsaturated fatty acids (n-3 PUFAs)consumption among Japanese adults. 90,504 subjects enrolled in the Japan Public Health Center-based Prospective Study(JPHC Study) were followed until December 2013. Dietary intake data were collected using a food frequency questionnaire. Hazard ratios (HRs) and 95% confidence intervals (CIs) werecalculated for gastric cancer risk associated with fish and shellfishconsumption and marine n-3 PUFAs (sum of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA)) using Cox proportional hazards models. Among those with avaliable data, we conducted a subgroup analysis takingH. pylori infectionand AGstatusinto consideration. There were 2,701 gastric cancer cases during an average of 15years of follow-up. We observed an increased gastric cancer risk for salted fish consumption for men [HR for fifth quintile versus first quintile 1.43 (95% CI 1.18-1.75)] and for women [HR 1.33 (95% CI 1.00-1.77)]. We observed a weak risk reduction trend for women as the intake ofmarine n-3 PUFAs increased (p-trend:0.07). When we included H. pylori infection and atrophic gastritis status in the analysis, the associations diminished. Our results suggest that salted fish increases gastric cancer risk for men and women, while marine n-3 PUFAs marginally decreases this risk among women in Japan.