One of the most intriguing findings, says Schabath, is that people who had never smoked had a reduced chance of developing the disease if they ate large quantities of phytoestrogen-rich food. "About 15 percent of lung cancers occur in lifetime never smokers, and besides exposures to second-hand smoke, other risk factors for these cancers are yet to be determined."
The study builds on the group's 2004 finding that women who used hormone replacement therapy - which restores estrogen to postmenopausal women - had a lower risk of developing lung cancer than women who did not use these agents, given a similar history of cigarette use. If estrogen drugs could protect against lung cancer, the researchers wondered if the same is true of foods that have naturally occurring low levels of estrogens. Several epidemiological studies of phytoestrogenic foods had suggested that might be the case for breast, endometrial and prostate cancers. The researchers further noted that lung cancer rates are substantially lower in Asian populations that typically eat larger amounts of phytoestrogens than is consumed in America.
Between 1995 and 2003, the research team enrolled 1,674 patients treated for lung cancer at M. D. Anderson, and 1,735 healthy "control" volunteers from private clinics in the Houston area. The participants were asked detailed questions about their diet for the year prior to their enrollment or to their cancer diagnosis, with the assumption that what they ate that year reflected their general eating pattern over a number of years, Schabath says.
The two groups were matched in terms of age, gender, ethnicity and smoking status. The researchers then divided consumption into three categories of foods that contain phytoestrogens: isoflavones (soy
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Contact: Laura Sussman
lsussman@mdanderson.org
713-745-2457
University of Texas M. D. Anderson Cancer Center
27-Sep-2005