The potential role of allium vegetables on endometrial cancer risk has been scarcely investigated and the results of previous Chinese studies are not easily applicable to Western populations. Therefore, we evaluated the relationship between onion and garlic intake and endometrial cancer, using data from an Italian case–control study.

We analysed data from a multi-centre case–control study of 454 endometrial cancer cases and 908 controls, admitted to the same hospitals for a wide spectrum of acute, non-neoplastic conditions. Information was collected by trained interviewers using a validated and reproducible FFQ. Multivariate odds ratios and 95 % confidence intervals were obtained after allowance for recognized confounding factors.

Compared with non-users, the OR of endometrial cancer for successive categories of onion intake were 0·94 (95 % CI 0·72, 1·21) for <2 portions/week and 0·40 (95 % CI 0·22, 0·72) for ≥2 portions/week, with a significant inverse trend in risk (P = 0·01). The OR for an increment of one portion (i.e. 80 g) of onions per week was 0·81 (95 % CI 0·70, 0·95). For garlic, the OR for successive categories of intake were 0·89 (95 % CI 0·68, 1·15) for intermediate use and 0·62 (95 % CI 0·42, 0·92) for high use, with a significant inverse trend in risk (P = 0·02).

Our study found a moderate protective role of allium vegetables on the risk of endometrial cancer.