Plasma folate, vitamin B6, vitamin B12, and homocysteine and pancreatic cancer risk in four large cohorts.

Cancer research
Q1
Jun 2007
Citations:84
Influential Citations:4
Observational Studies (Human)
83
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Methods
Four prospective cohorts (Nurses’ Health Study, Health Professionals Follow-up Study, Physicians’ Health Study, Women’s Health Initiative) were used in a nested case-control design. Participants were adults including women and men; final analysis included 208 pancreatic cancer cases and 623 controls with baseline blood samples collected before diagnosis; cases diagnosed after blood collection; controls matched to cases on year of birth, cohort, smoking status, fasting status, and month of blood draw; plasma folate, PLP (vitamin B6), vitamin B12, and homocysteine measured in blinded assays.
Results
Overall, plasma levels of folate, PLP, B12, and homocysteine were not associated with pancreatic cancer risk. Highest vs lowest quartiles: folate OR 1.20 (0.76–1.91); PLP OR 0.80 (0.51–1.25); B12 OR 0.91 (0.57–1.46); homocysteine OR 1.43 (0.90–2.28). Among nonusers of multivitamins, there is an inverse trend for folate, PLP, and B12; PLP shows a statistically significant inverse association (top vs bottom quartile OR 0.47; 95% CI 0.24–0.92), attenuated to OR 0.51 (0.25–1.02) with further adjustment. In BMI below median subgroups, stronger inverse relationships are observed for PLP (top vs bottom OR 0.19; 95% CI 0.06–0.59) and B12 (0.27; 0.09–0.80) among nonmultivitamin users; folate weaker (0.41; 0.14–1.17). Among never smokers who were nonmultivitamin users, folate suggests a non-significant risk reduction (OR 0.30; 95% CI 0.08–1.04). Overall, findings imply that any potential protective effect may relate to dietary folate and to non-supplement sources, but not to supplements, and require confirmation in future studies.
Limitations
Observational pooled design across four cohorts with varying covariate assessment; potential residual confounding; measurement error in biomarker assays; pre-fortification era folate measurements; limited power in subgroup analyses; multiple comparisons; results may not generalize to all populations.

Abstract

Folate deficiency induces DNA breaks and may alter cellular capacity for mutation and epigenetic methylation. Few studies have examined the influence of one-carbon nutrients on pancreatic cancer risk, although recent studies suggest a potential prote...