Lung cancer is the leading cause of cancer death among women worldwide. With a 5-year survival rate of only 15%, it is estimated that lung cancer will cause almost twice as many deaths as breast cancer among US women in 2012. Prognosis is affected by a number of factors, including age at diagnosis and tumor stage. It also appears that female sex hormones may affect lung cancer survival.
Even tissues that are not involved in reproduction can have estrogen receptors, and of these non-reproductive tissues, lungs have the highest number of these receptors. This may explain in part why women who take hormone therapy are at higher risk for lung cancer. In contrast, those who are treated with the anti-estrogen breast cancer drug tamoxifen are at lower risk.
Chinese investigators previously demonstrated that soy consumption may decrease risk of developing lung cancer by 40 percent in non-smokers. In new research, these same researchers set out to determine whether soyfoods affect survival in people who have been diagnosed with lung cancer. Researchers involved in this study were associated with several different institutions including Vanderbilt University Medical Center in Nashville, the Shanghai Cancer Institute in Shanghai and the US National Cancer Institute in Bethesda.
Their analysis included 444 women with lung cancer who had been enrolled in the Shanghai Women’s Health Study. During follow up, 318 of the women died. The researchers assessed the impact of soyfoods on survival by dividing the subjects into five groups according to their intake. Women who consumed less than one serving of soy per day were as much as 80 percent more likely to die from lung cancer than those who consumed a serving per day. Consuming more than one serving per day offered little additional protection. The protective effects of soy consumption were even more pronounced among non-smokers.
This study is the first to evaluate whether usual soy consumption impacts the prognosis of lung cancer patients. It’s not known if women who add soyfoods to their diet after a diagnosis of lung cancer will have the same benefits. However, the growing body of research suggests that eating more soy is a good decision for any woman who wants to reduce her risk for lung cancer.
Yang G, Shu XO, Li HL, et al. Prediagnosis soy food consumption and lung cancer survival in women. J Clin Oncol 2013.