"We found women who were treated with tamoxifen for breast cancer were less likely to die from lung cancer than women in the general population," says Elisabetta Rapiti, MD, MPH, a medical researcher at the University of Geneva in Switzerland.
In contrast, breast cancer patients who were not treated with anti-hormone drugs had the same risk of lung cancer death as other women, she tells WebMD.
Tamoxifen, which blocks the activity of estrogen, thereby slowing tumor growth, has been used for decades to treat breast cancer.
In recent years, its use has been largely supplanted by aromatase inhibitors, which actually shut down the body's ability to make estrogen. Although the new study involved too few women treated with aromatase inhibitors to draw any firm conclusions, Rapiti says she believes these drugs would also help combat lung cancer.
"We believe it's an anti-estrogen effect," she says. "But much more study is needed."
The findings were presented at the annual San Antonio Breast Cancer Symposium.
Hormone Drugs Raise Risk of Dying From Lung Cancer
The new research builds on findings, presented earlier this year at a major cancer meeting, showing that the hormone replacement therapy taken by millions of women to relieve hot flashes and other symptoms of menopause may raise the risk of dying from lung cancer.
The study involved 6,715 women living in the Geneva region of Switzerland who were diagnosed with breast cancer between 1980 and 2003. Forty-six percent of the women were on anti-estrogen therapy, primarily tamoxifen.
By the end of 2007, 40 of the women had been diagnosed with lung cancer.
The risk of developing lung cancer in breast cancer patients treated with anti-estrogen drugs and breast cancer patients not treated with the drugs was the same as women in the general population.
However, the risk of dying from lung cancer was more than sevenfold higher among women who received anti-estrogen therapy than among women in the general population.
"Fifteen of the women on anti-estrogen drugs died of lung cancer, while only two deaths from lung cancer would be expected in a similar number of women of the same ages in the general population," Rapiti says.
P. Kelly Marcom, MD, an expert in cancer genetics at Duke University, tells WebMD that estrogen is present in tissue throughout the body, creating a hormonal environment that is conducive to the growth and spread of cancer cells.
"There's more estrogen in breast cells, which is why we use the anti-estrogen drugs to treat breast cancer, but lung tissue has estrogen, too. So one would expect the anti-estrogen drugs to impact lung cancer, just in a more subtle way," he says.
Rapiti says that studies looking at whether adding anti-hormone drugs to traditional chemotherapy can improve the prognosis of lung cancer patients are under way.