Phytoestrogens Inhibit Lung Cancer 32965

Phytoestrogens Inhibit Lung Cancer

HOUSTON--Dietary intake of phytotestrogens reduces the risk of lungcancer, according to a study published in the Journal of the American MedicalAssociation (JAMA), http://jama.ama-assn.org/294:1493-1504, 2005).

In the eight-year study, researchers used food frequency questionnaires tocollect demographic information and assess dietary intake of 12 individualphytoestrogens in subjects from an ongoing case-control study of 1,674 patientswith lung cancer and 1,735 matched healthy controls. Risk of lung cancer wasestimated using unconditional, multivariable logistic regression analysesstratified by sex and smoking status, and adjusted for established and putativelung cancer risk factors. With each increasing quartile of phytoestrogen intake,risk of lung cancer dropped. Subjects with the highest intake of totalphytosterols, isoflavones, lignans and phytoestrogens showed reductions in riskof lung cancer ranging from 21 percent for phytosterols to 46 percent for totalphytoestrogens derived solely from food sources.

The researchers also discovered gender-specific effects. For men,statistically significant trends for the inverse association betweenphytoestrogen intake and lung cancer were noted for each phytoestrogen group,with protective effects for the highest quartile of intake ranging from 24percent for phytosterols to 44 percent for isoflavones; in women, significanttrends were only present for intake of total phytoestrogens derived solely fromfood sources, with a 34-percent protective effect for the highest quartile ofintake. High phytoestrogen intake had an apparently beneficial effect in bothindividuals with no history of smoking as well as current smokers, but thebeneficial effects were less in former smokers. In women taking hormone therapyand consuming phytoestrogens, statistically significant effects were evidentbetween the combination of hormone therapy and phytoestrogen intake;specifically, high intake of the lignans enterolactone and enterodiol and use ofhormone therapy were associated with a 50-percent reduction in risk of lungcancer.

The researchers concluded while there are limitations and concerns regardingcase-control studies of diet and cancer, these data provide further support forthe limited but growing epidemiologic evidence that phytoestrogens areassociated with a decrease in risk of lung cancer, and noted confirmation ofthese findings is still required in large-scale, hypothesis-driven, prospectivestudies.