Vitamin B6 Inversely Associated with Lung Cancer

LYON, FranceSerum levels of vitamin B6 and methionine were inversely associated with risk of lung cancer, according to a recently published study in JAMA (2010;303(23):2377-2385). Context  B vitamins and factors related to 1-carbon metabolism help to maintain DNA integrity and regulate gene expression and may affect cancer risk. The European Prospective Investigation into Cancer and Nutrition (EPIC) recruited 519,978 participants from 10 countries between 1992 and 2000, 385,747 of which donated blood. By 2006, 899 lung cancer cases were identified and 1,770 control participants were individually matched by country, sex, date of birth, and date of blood collection. Serum levels were measured for six factors of 1-carbon metabolism and cotinine. Odds ratios (ORs) of lung cancer by serum levels of four B vitamins (B2, B6, folate [B9], and B12), methionine and homocysteine were the main outcomes measured.

Within the entire EPIC cohort, the age-standardized incidence rates of lung cancer (standardized to the world population, aged 35-79 years) were 6.6, 44.9 and 156.1 per 100,000 person-years among never, former, and current smokers for men, respectively. The corresponding incidence rates for women were 7.1, 23.9, and 100.9 per 100,000 person-years, respectively. After accounting for smoking, a lower risk for lung cancer was seen for elevated serum levels of B6, as well as for serum methionine. Similar and consistent decreases in risk were observed in never, former, and current smokers, indicating that results were not due to confounding by smoking. The magnitude of risk was also constant with increasing length of follow-up, indicating that the associations were not explained by preclinical disease. A lower risk was also seen for serum folate, although this was apparent only for former and current smokers. When participants were classified by median levels of serum methionine and B6, having above-median levels of both was associated with a lower lung cancer risk overall, as well as separately among never, former and current smokers.