There are suggestions of an inverse association between folate intake and serum folate levels and the risk of oral cavity and pharyngeal cancers (OPCs), but most studies are limited in sample size, ...with only few reporting information on the source of dietary folate. Our study aims to investigate the association between folate intake and the risk of OPC within the International Head and Neck Cancer Epidemiology (INHANCE) Consortium. We analyzed pooled individual‐level data from ten case–control studies participating in the INHANCE consortium, including 5,127 cases and 13,249 controls. Odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were estimated for the associations between total folate intake (natural, fortification and supplementation) and natural folate only, and OPC risk. We found an inverse association between total folate intake and overall OPC risk (the adjusted OR for the highest
vs
. the lowest quintile was 0.65, 95% CI: 0.43–0.99), with a stronger association for oral cavity (OR = 0.57, 95% CI: 0.43–0.75). A similar inverse association, though somewhat weaker, was observed for folate intake from natural sources only in oral cavity cancer (OR = 0.64, 95% CI: 0.45–0.91). The highest OPC risk was observed in heavy alcohol drinkers with low folate intake as compared to never/light drinkers with high folate (OR = 4.05, 95% CI: 3.43–4.79); the attributable proportion (AP) owing to interaction was 11.1% (95% CI: 1.4–20.8%). Lastly, we reported an OR of 2.73 (95% CI:2.34‐3.19) for those ever tobacco users with low folate intake, compared with nevere tobacco users and high folate intake (AP of interaction =10.6%, 95% CI: 0.41‐20.8%). Our project of a large pool of case–control studies supports a protective effect of total folate intake on OPC risk.
What's new?
Folate is essential to DNA synthesis and repair, suggesting that folate deficiency, in disrupting normal DNA processes, may facilitate the development of certain cancers, including oral and pharyngeal cancer (OPC). The relationship between folate intake and risk of OPC, however, is unclear. In this analysis of data from the International Head and Neck Cancer Epidemiology (INHANCE) Consortium, high levels of folate intake were found to be inversely associated with overall OPC risk. The association was strongest for cancer of the oral cavity. Risk of OPC was highest among heavy alcohol drinkers with low folate levels.
Evidence of associations between single nutrients and head and neck cancer (HNC) is still more limited and less consistent than that for fruit and vegetables. However, clarification of the protective ...mechanisms of fruit and vegetables is important to our understanding of HNC etiology.
We investigated the association between vitamin C intake from natural sources and cancer of the oral cavity/pharynx and larynx using individual-level pooled data from ten case-control studies (5959 cases and 12248 controls) participating in the International Head and Neck Cancer Epidemiology (INHANCE) consortium. After harmonization of study-specific exposure information via the residual method, adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using unconditional multiple logistic regression models on quintile categories of ’non-alcohol energy-adjusted’ vitamin C intake. In the presence of heterogeneity of the estimated ORs among studies, we derived those estimates from generalized linear mixed models.
Higher intakes of vitamin C were inversely related to oral and pharyngeal (OR=0.54, 95% CI: 0.45–0.65, for the fifth quintile category versus the first one, p for trend<0.001) and laryngeal cancers (OR=0.52, 95% CI: 0.40–0.68, p for trend=0.006), although in the presence of heterogeneity among studies for both sites. Inverse associations were consistently observed for the anatomical subsites of oral and pharyngeal cancer, and across strata of age, sex, education, body mass index, tobacco, and alcohol, for both cancer sites.
The inverse association of vitamin C intake from foods with HNC may reflect a protective effect on these cancers; however, we cannot rule out other explanations.
There are suggestions of an inverse association between folate intake and serum folate levels and the risk of oral cavity and pharyngeal cancers (OPC), but most studies are limited in sample size, ...with only few reporting information on the source of dietary folate. This study aims to investigate the association between folate intake and the risk of OPC within the International Head and Neck Cancer Epidemiology (INHANCE) Consortium.
We analyzed pooled individual-level data from 10 case-control studies participating in the INHANCE consortium, including 5,127 cases and 13,249 controls. Odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were estimated for the associations between total folate intake (natural, fortification and supplementation) and natural folate only, and OPC risk.
We found an inverse association between total folate intake and overall OPC risk (the adjusted OR for the highest versus the lowest quintile was 0.65, 95% CI: 0.43–0.99), with a stronger association for oral cavity (OR=0.57, 95% CI: 0.43–0.75). A similar inverse association, though somewhat weaker, was observed for folate intake from natural sources only (OR=0.64, 95% CI: 0.45–0.91).
The highest OPC risk was observed in heavy alcohol drinkers with low folate intake as compared to never/light drinkers with high folate (OR=4.05, 95% CI: 3.43–4.79); the attributable proportion due to interaction was 11.1%(95% CI: 1.4–20.8%).
The present project of a large pool of case-control studies supports a protective effect total folate intake on OPC risk.
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