Serum vitamin E level and risk of female cancers

A sample of 15,093 women, aged 15-99 and initially free from cancer, participated in the Finnish Social Insurance Institution's Mobile Clinic Health Survey in 1968-71. A record linkage to the Cancer Registry revealed that during a mean follow-up of eight years cancer was diagnosed in 313 women. Serum alpha-tocopherol levels were measured from stored samples (at -20 C) of the cancer patients and of 578 controls, matched for municipality and age. An inverse relation was observed between alpha-tocopherol level and risk of cancer, even if the cancers in the first two years of follow-up were excluded. Women in the lowest quintile for alpha-tocopherol levels compared to those with higher values had a 1.6-fold (95% confidence interval: 1.1-2.5) risk of cancer as adjusted for possible confounding effects of several other factors. A low level of alpha-tocopherol in general strongly predicted epithelial cancers while it carried an only slightly elevated risk of cancers in reproductive organs exposed to oestrogens. The results suggest that a low vitamin E intake is a risk factor for cancer in many, but not all, organs. The expression of its protective effect may depend on the primary causes, which vary between different cancers.