June 1 (HealthDay News) -- The current use of combined hormone replacement therapy (HRT) is associated with a higher risk of dying for women diagnosed with non-small cell lung cancer, a new study shows.
The risk was highest in current smokers, less high in former smokers and least high in women who never smoked, say researchers reporting Saturday at the annual meeting of the American Society of Clinical Oncology (ASCO), in Orlando, Fla.
"This is a major concern," said study lead author Dr. Rowan Chlebowski, a medical oncologist with the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center. "In current smokers, one in 100 experience avoidable death from non-small cell lung cancer. Women almost certainly shouldn't be using both combined hormone replacement therapy and tobacco at the same time," he said at a Saturday ASCO news briefing.
"We want to do everything we can to prevent lung cancer," added Dr. Jeffrey Crawford, chief of medical oncology at Duke Comprehensive Cancer Center in Durham, N.C. "But if you're a current or former smoker, in particular, this is another reason not to consider hormone replacement therapy."
According to Chlebowski, about 15 percent of postmenopausal women in the United States still take hormone therapy, although that is down from previous years.
The new results, based on data from the landmark Women's Health Initiative (WHI) trial, relate only to the combined estrogen-plus-progestin regimen of hormone therapy, not to the use of estrogen on its own.
The findings do appear to be another blow for hormone replacement therapy, which has already been associated with an elevated risk of heart attack, stroke and breast cancer.
This new findings were based a secondary analysis of data on more than 16,600 women participating in the Women's Health Initiative. Some of these women had taken combined hormone therapy -- conjugated equine estrogen (CEE) plus medroxyprogesterone acetate (MPA) -- while others had not.
Smoking rates were similar in the two groups. Half of the participants were never smokers, 40 percent were past smokers, and only 10 percent currently smoked.
The risk of developing lung cancer was similar in both groups, but women taking the hormones were 61 percent more likely to die of lung cancer than women in the placebo arm (67 women died in the hormone group vs. 39 of those taking a placebo).
Over a period of almost eight years of treatment and follow-up, 3.4 percent of smokers taking hormone therapy who also developed lung cancer died of the disease, compared to 2.3 percent of smokers who were diagnosed with the illness but did not take HRT, the study found.
"Median survival was 9.4 months versus 16.1 months in favor of the group that did not receive estrogen plus progestin," Chlebowski said.
The findings build on previous research that has hinted that estrogen might play a role in non-small cell lung cancer.
"Such a large trial helps to bring that information home and, especially in smokers, we know that there's an interaction between HRT, lung cancer and smoking from prior observational studies and pre-clinical studies," said Dr. Karen Reckamp, assistant professor of medicine at City of Hope Cancer Center in Duarte, Calif. "We see more and more non-smoking women getting lung cancer in general and often younger women. We know that there are estrogen receptors in the lung and in lung cancers and so there's definitely an interaction between the development of lung cancer and hormones."
There's more on results from the Women's Health Initiative at the U.S. National Heart, Lung, and Blood Institute.
SOURCES: Jeffrey Crawford, M.D., chief, medical oncology, Duke Comprehensive Cancer Center, Durham, N.C.; Karen Reckamp, M.D., assistant professor of medicine, thoracic oncology division, City of Hope Cancer Center, Duarte, Calif.; May 30, 2009, American Society of Clinical Oncology news conference with Rowan Chlebowski, M.D., Ph.D., medical oncologist, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center