Association between dietary folate intake and clinical outcome in head and neck squamous cell carcinoma.

BACKGROUND The association between dietary folate intake, two polymorphisms in methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TYMS), and survival in head and neck squamous cell carcinoma (HNSCC) patients is not clarified. PATIENTS AND METHODS We conducted a retrospective cohort study of 437 HNSCC patients treated at Aichi Cancer Center. We evaluated the survival impact of pretreatment dietary folate intake, which was estimated using a food-frequency questionnaire, and two polymorphisms, MTHFR C677T and a 6-bp insertion/deletion in the 3'-untranslated region of TYMS, using multivariate proportional hazard models. RESULTS Patients with high folate intake (≥320 μg/day; n=144) had significantly higher survival than patients with low or medium folate intake (<320 μg/day; n=278; 79.1% versus 68.2%, respectively, P=0.020). This association was consistent with multivariate analyses adjusted for established prognostic factors (hazard ratio 0.56; 95% confidence interval 0.37-0.84). MTHFR and TYMS polymorphisms did not show significant association with survival, although the TYMS 6-bp insertion allele showed potential association with a reduced risk of death. Notably, no significant interaction was observed between folate intake and the two examined polymorphisms. CONCLUSIONS High pretreatment dietary folate intake was identified as an independent prognostic factor associated with improved clinical outcomes in HNSCC patients. Further study is warranted.