The study was based on data collected during the Women's Health Initiative (WHI) study, which was halted early when the health risks associated with HRT were found to exceed the benefits. The WHI study found that women who took combined hormone replacement therapy had higher risks of heart disease, stroke, breast cancer, and other health problems.
Although the risk of death from any cause did not differ between the groups at the time the study ended, researchers say additional follow-up now shows a higher risk of lung cancer deaths among women who took combined HRT.
"These findings should be considered before the initiation or continuation of combined hormone therapy in postmenopausal women, especially those with a high risk of lung cancer, such as current smokers or long-term past smokers," write researcher Rowan Chlebowski, MD, of the Los Angeles Biomedical Research Institute at Harbour-UCLA Medical Center in Torrance, Calif., and colleagues in The Lancet.
The WHI study involved 16,608 postmenopausal women at 40 different centers across the U.S. who were randomly assigned to take a daily dose of hormone replacement therapy or a placebo.
The percentages of women who died from lung cancer from the HRT group and the placebo group were low (0.11% and 0.06%), but statistically significant. When they looked at deaths due to lung cancer, they found 73 women who took HRT died of lung cancer compared with 40 in the placebo group. The researchers found this was mainly due to a higher number of deaths from non-small-cell lung cancer in the combined HRT group.
"These results, along with the findings showing no protection against coronary heart disease, seriously question whether hormone-replacement therapy has any role in medicine today," writes Apar Kishor Ganti, MD, of the University of Nebraska Medical Center in Omaha, in a commentary that accompanies the study. "It is difficult to presume that the benefits of routine use of such therapy for menopausal symptoms outweigh the increased risks of mortality, especially in the absence of improvement in the quality of life."