Hormone therapy may nearly double the risk of lung cancer

Hormone replacement therapy, already linked to increases in 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 nail in the coffin for a therapy that is already in rapidly declining use.

The findings "seriously question whether hormone-replacement therapy has any role in medicine today," wrote Dr. Apar Kishor Ganti of the University of Nebraska Medical Center 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, director of translational tumor immunology at the John Wayne Cancer Institute in Santa Monica, Calif., 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 administration of a combination of estrogen and progestin could relieve debilitating symptoms of menopause and reduce the risk of heart attack and stroke. The hormone replacement arm, which enrolled more than 16,000 women, was halted prematurely after about 51/2 years when it was observed that the risks far outweighed any potential benefits.

The therapy not only did not protect against heart disease and stroke, but it yielded only 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 the rate of breast cancer rose by at least 15 percent during the 1990s when HRT was blooming, then dropped sharply when many women abandoned the treatment after a 2002 report on the subject.

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 laboratory 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 the University of California, Los Angeles' Jonsson Comprehensive Cancer Center. Among other effects, the hormone promotes the growth of blood vessels that nourish growing tumors.

"We've been suspecting for a long time that this is an area we need to investigate," Pietras said. The need is especially dramatic because the incidence of lung cancer in women has been growing and more women now 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.