Dietary intake of lignans and risk of esophageal and gastric adenocarcinoma: a cohort study in Sweden.

High intake of phytoestrogen lignans has been found to be associated with decreased risk of esophageal adenocarcinoma in our previous population-based case-control study in Sweden. To further evaluate this possible association, we tested the hypothesis of an inverse association between dietary lignan intake and risk of esophageal and gastric adenocarcinoma using a prospective design. In a population-based cohort study in Sweden, 81,670 participants who were cancer-free at baseline were followed up during 1998 to 2009. All participants completed a 96-item food frequency questionnaire (FFQ), which was used to assess dietary exposure to lignans (secoisolariciresinol, matairesinol, lariciresinol, pinoresinol, medioresinol, and syringaresinol). All cases of esophageal, gastroesophageal junctional, and gastric adenocarcinoma were identified through linkage to the Swedish Cancer Register. Cox proportional hazard models were used to estimate HRs and 95% confidence intervals (CI), with adjustment for potential confounding factors. During an average follow-up of 9.9 years, a total of 211 cases were identified, including 83 cases of esophageal or junctional adenocarcinoma, and 128 cases of gastric adenocarcinoma. There was no statistically significant association between dietary intake of lignans and any of the studied adenocarcinomas. Compared with participants in the lowest quartile of lignan intake, the adjusted HR of the highest quartile was 0.96 (95% CI, 0.46-2.00; P(trend) = 0.70) for adenocarcinoma of the esophagus or gastroesophageal junction, and 0.89 (95% CI, 0.52-1.55: P(trend) = 0.78) for gastric adenocarcinoma. No clear support for a protective role of dietary intake of lignans in the development of esophageal or gastric adenocarcinoma was found.