Hormone replacement therapy, already linked to increased risk of breast cancer, heart disease and stroke, nearly doubles a woman's risk of dying from lung cancer, researchers reported Saturday in a finding that may be the final blow for a therapy that is already in rapidly declining use.
The findings "seriously question whether hormone-replacement therapy has any role in medicine today," Dr. Apar Kishor Ganti of the University of Nebraska Medical Center wrote in an editorial accompanying the online publication of the report in the medical journal Lancet.
The link to lung cancer "is yet another reason to not use hormone replacement therapy if it can be avoided," said Dr. Mark Faries of the John Wayne Cancer Institute in Santa Monica, who was not involved in the research. "It raises the bar for deciding to do HRT."
The findings come from the Women's Health Initiative, a large study originally begun in 1991 to demonstrate, in part, that administering estrogen and progestin could relieve debilitating symptoms of menopause and reduce the risk of heart attack and stroke. The hormone replacement part of the study, which enrolled more than 16,000 women, was halted prematurely after about 5 1/2 years when it was observed that the risks far outweighed any potential benefits.
Not only did the therapy not protect against heart disease and stroke, but it also yielded questionable improvements in quality of life and produced a small but statistically significant increase in the risk of heart disease, stroke and breast cancer. Several subsequent reports have shown that breast cancer rose by at least 15% during the 1990s when HRT was blooming, then dropped sharply when many women abandoned the treatment after a 2002 report.
Treatment with estrogen has a deleterious effect on breast cancer patients because the hormone binds to estrogen receptors on tumor tissue, accelerating its growth. Recent studies have shown that lung tissue also has estrogen receptors and that the accelerated growth is even more dramatic in lung tumor cells, according to Dr. Richard J. Pietras, who directs the Stiles program on oncology at UCLA's Jonsson Comprehensive Cancer Center.
"We've been suspecting for a long time that this is an area we need to investigate," Pietras said. The incidence of lung cancer in women has been growing, and more women die from it than from breast, ovarian and colon cancers combined. About 99,000 women are diagnosed with lung cancer each year, and 71,000 die from it.
