Abstract 1104: Folate intake and colorectal cancer risk during 36 years of follow-up in US women: A prospective cohort study

Abstract

Abstract Background: Folate intake has been reported to be associated with a lower colorectal cancer (CRC) risk in several epidemiological studies. However, there are concerns about the potential for cancer promotion with an overly-abundant folate intake, especially after the mandatory folate fortification in the United States in 1998. Method: We investigated the association between folate intake and CRC risk among 83,165 women in the Nurses' Health Study, including 18 years of post-fortification follow-up; 2268 incident CRC cases were ascertained from 1980 to 2016. Folate intake from foods and supplements was assessed at baseline and updated every 4 years using a validated food-frequency questionnaire. Multivariate hazards ratios (HR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards regression. Results: Over the entire follow-up period (1980-2016), higher total folate intake was associated with a decreased risk of CRC (HRQ5vsQ1=0.80; 95% CI: 0.64-0.99). This association was stronger when total folate was assessed 12-24 years before CRC diagnosis. Multivitamin use for >15 years, but not a shorter duration of use, was associated with lower CRC risk. In the post-fortification period (1998-2016, n= 1169 CRC cases), high total folate intake (HRQ5vsQ1=0.80; 95% CI: 0.64-1.00) and current multivitamin uses, regardless of duration, were each associated with lower CRC risk. Conclusions: There was no evidence that high folate intake in the post-fortification period was related to increased CRC risk. Rather, high total folate intake was inversely associated with risk of CRC. Citation Format: Fenglei Wang, Kana Wu, Yanping Li, Stephanie Smith-Warner, Edward Giovannucci, Walter Willett. Folate intake and colorectal cancer risk during 36 years of follow-up in US women: A prospective cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1104.