Premium
Pre‐diagnostic plasma unmetabolized folic acid and the risk of colorectal cancer (136.5)
Author(s) -
Cho Eunyoung,
Townsend Mary,
Selhub Jacob,
Paul Ligi,
Rosner Bernard,
Fuchs Charles,
Willett Walter,
Giovannucci Edward
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.136.5
Subject(s) - medicine , colorectal cancer , relative risk , prospective cohort study , confidence interval , gastroenterology , folic acid , cohort study , cancer
Objective: To investigate the association between pre‐diagnostic plasma unmetabolized folic acid levels and risk of colorectal cancer (CRC). Methods: We evaluated pre‐diagnostic plasma levels of unmetabolized folic acid in relation to the risk of CRC in nested case‐control studies within two prospective cohort studies, Nurses’ Health Study (NHS) and Health Professionals Follow‐up Study (HPFS). Blood samples were collected prior to folic acid fortification (in 1989‐1990 in NHS and 1993‐1995 in HPFS). A total of 618 cases of CRC up to 2010 follow‐up and 1215 matched controls (344/680 women and 274/532 men) were included in the analysis. Results: Unmetabolized folic acid was detected in 22 % of the controls and 21% of the CRC cases. Among those detected, the median value of unmetabolized folic acid was 0.61 nmol/L in both controls and cases. Overall, pre‐diagnostic plasma levels of unmetabolized folic acid were not associated with CRC risk. Compared to those undetected, the multivariate relative risks (RRs) of CRC were 1.14 (95% confidence interval (CI), 0.79‐1.65) for <0.5 nmol/L and 1.13 (95% CI, 0.79‐1.60; P for trend, 0.30) for 蠅0.5 nmol/L. When we stratified the association by sex, there was a positive association between unmetabolized folic acid levels and CRC risk among men (RR=1.58 [95% CI 1.01‐2.49] for 蠅0.5 nmol/L vs. undetected) but not among women (RR=0.64 [95% CI 0.39‐ 1.05] for the same comparison; P for interaction=0.05). The association was also positive among those with methylene‐tetrahydrofolate reductase (MTHFR) CT/TT genotype (RR=2.20 [95% CI 1.24‐3.90] for 蠅0.5 nmol/L vs. undetected) but not among those with CC genotype (RR=0.49 [95% CI 0.22‐1.08] for the same comparison; P for interaction=0.03) Conclusions: Pre‐diagnostic plasma levels of unmetabolized folic acid from pre‐fortification period were not associated with the risk of CRC. The positive association in some subgroups of the population needs to be further explored. Grant Funding Source : Supported by CA136950, CA87969, and CA55075