Individuals who took a dietary supplement called "factor D", which included selenium, vitamin E, and beta-carotene, continued to have lower gastric cancer and overall mortality 10 years after supplementation ceased compared with individuals who did not take the supplements, according to long-term follow-up data from the randomized, double-blind General Population Nutrition Intervention Trial in Linxian, China.
The trial tested the impact of four dietary supplement combinations on gastric and esophageal cancer incidence and overall mortality in a nutritionally-deprived population. The trial enrolled 29,584 adults between the ages of 40 and 69 years. Participants took dietary supplements from 1986 to 1991. The initial results from the study showed a significant reduction in risk of gastric cancer and overall mortality in individuals taking factor D.
In the current analysis, Philip R. Taylor, M.D., Sc.D., of the National Cancer Institute in Bethesda, Md., and colleagues at the Chinese Academy of Medical Sciences in China examined 10-year follow-up data.
Individuals who took factor D continued to show benefits, with a 5% reduction in overall mortality (from a cumulative mortality of 33.62% of participants not taking factor D to 32.19% of participants taking factor D) and an 11% reduction in gastric cancer mortality (from a cumulative gastric cancer mortality of 4.28% in the no-factor D group to 3.84% in the factor D group). Individuals who were under the age of 55 derived the majority of benefit from the supplement. Esophageal cancer incidence decreased by 17% in participants under the age of 55, but increased by 14% in those participants over age 55.
"The persistence of risk reduction for up to 10 years after treatment in this trial reinforces the validity of the original trial findings and is consistent with an emerging new paradigm in cancer prevention, namely, that prevention may be achievable with short-term as opposed to life-long treatment," the authors write.
The research is published in the March 24 online issue of the Journal of the National Cancer Institute.
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