Circulating folate levels and colorectal adenoma: a case-control study and a meta-analysis

Abstract

BACKGROUND/OBJECTIVESThe relationship between folate and colorectal neoplasia remains controversial. We examined the association between serum folate concentrations and colorectal adenomas in a case-control study of Korean adults and conducted a meta-analysis.SUBJECTS/METHODSOur case-control study included 113 pairs of case and control who underwent colonoscopy and provided blood samples. We used multivariable conditional logistic regression models to obtain the odds ratios and 95% confidence interval (CIs). For meta-analysis, we identified the relevant studies by searching the PubMed database up to February 2017, included our case-control study and combined the study-specific relative risks (RRs) using a random-effects model.RESULTS In this case-control study, we included 58 men and 55 women with colorectal adenomas and sex and fasting status matched the controls. We did not find any significant association between the serum folate levels and colorectal adenomas in either men or women. For meta-analysis, a total of eleven studies were included in our analysis and classified into two groups; polyp clearance group (PC) for the studies that included participants who underwent endoscopies and had their polyps removed at baseline; and no polyp clearance group (NPC) for the studies that included participants whose histories of endoscopies were unknown or who underwent their first endoscopies. Four PC (1,311 cases and 1,672 non-cases) and eight NPC studies (3,501 cases and 11,347 non-cases) were included. The combined RRs (95% CIs) comparing the bottom with the top categories of circulating folate levels were 1.07 (0.97-1.18) for the NPC group but 1.45 (1.16-1.74) for the PC group.CONCLUSIONSLow circulating folate levels were associated with new adenoma formation.

Association Between Risk Factors for Colorectal Cancer and Risk of Serrated Polyps and Conventional Adenomas

“…For example, although total fiber intake was not associated with overall conventional adenomas or SPs, it was associated with lower risk advanced conventional adenomas, in line with the meta-analysis findings that fiber was associated with a lower risk of CRC. 57 Similarly, we confirmed previous findings that intake of total calcium, vitamin D, and folate was inversely associated with risk of conventional adenomas 58-60 . In contrast, we did not find any association between calcium and folate intake and risk of SPs.…”

MTHFR Gene C677T Polymorphism (rs1801133) and Susceptibility to Colorectal Polyps in an Azerbaijani Population

“…The current evidence indicates a clear link between folate metabolism and the development of both CRA and CRC. In a meta-analysis of eleven epidemiologic studies by Park et al, low folate levels were associated with a greater prevalence or incidence of colorectal adenomas, suggesting that low folate may contribute to colorectal cancer in the early stages [ 31 ]. Numerous studies have found that folate intake was inversely associated with colorectal cancer and adenoma risk, with the highest folate intake depicting a 20–40% lower risk [ 32 ].…”

Enzymes involved in folate metabolism and its implication for cancer treatment

“…Folate deficiency is reportedly associated with the development of neural tube defects and congenital disorders, anemia, atherosclerosis, adverse pregnancy outcomes, neuropsychiatric disorders, and cognitive impairments [3]. Accumulating epidemiological evidence suggests an inverse relationship between dietary folate intake or blood folate levels and the risk of multiple malignancies, including lung, oropharyngeal, esophageal, stomach, colorectal, prostate, and breast cancer [3][4][5][6][7]. However, clinical and preclinical studies suggest that excess FA consumption is associated with an increased risk of progression of established precancerous lesions, indicating that folate may play a dual modulatory role in cancer development and progression [5,6,[8][9][10].…”