Anti-estrogens linked to fewer lung cancer deaths

NEW YORK (Reuters Health) - Anti-estrogen drugs such as tamoxifen may reduce a woman’s risk of dying from lung cancer, suggests a new study. The analysis included a very small number of women with lung cancer, however, and the findings do not mean that women should take these drugs to prevent or treat lung cancer, doctors say.

Lung cancer kills more people than any other type of cancer. In the United States, over 200,000 people are diagnosed with lung cancer every year, and more than 150,000 die from it.

Research suggests that some hormones, including estrogen, may play a role in the progression of the disease by interacting with lung cancer cells.

Anti-estrogens, like tamoxifen, are currently used to treat women who have certain types of breast cancer that need estrogen to grow. Because some prior research, including the large Women’s Health Initiative study of hormone replacement therapy, showed that women taking estrogen had an increased risk of dying from lung cancer, some scientists began wondering if the opposite might be true. That is, if women taking drugs designed to block the effects of estrogen might be at lower-than-average risk of dying from lung cancer.

The current results are “intriguing,” Dr. Apar Ganti, who studies lung cancer at the University of Nebraska Medical Center but was not involved in the new research, told Reuters Health. “It provides more evidence to the role of estrogen in lung cancer,” he said. However, “this study does not say that you should treat lung cancer with tamoxifen or any other anti-estrogens,” he added.

In the new analysis, researchers led by Dr. Christine Bouchardy of the University of Geneva in Switzerland tracked more than 6,000 women with breast cancer who had been entered into a Swiss cancer registry between 1980 and 2003.

From that registry, the researchers gathered information on which women had been treated with tamoxifen -- sold under multiple names including Nolvadex. They also determined those who were later diagnosed with lung cancer, and who had died from it through 2007.

Bouchardy and her colleagues then calculated the chances of getting lung cancer and of dying from it in women who took tamoxifen and those who didn’t.

The results, published in the journal Cancer, show that if about 10,000 women took tamoxifen for a year, five or six would get lung cancer, compared to about eight women out of 10,000 who are not taking tamoxifen. There were so few lung cancer cases in total, though -- only 40 out of all 6,655 women in the study -- the differences between the two groups could have been due to chance.

When the team looked at women who were not only diagnosed with lung cancer but also died of the disease, tamoxifen did appear to make a significant difference. The findings suggest that less than one out of 10,000 women taking the drug for a year will die of lung cancer, compared to four or five out of 10,000 not taking tamoxifen.

Nevertheless, when the authors took into account women’s age at treatment and other factors, women taking tamoxifen in the study were not statistically less likely to die of lung cancer than women in the general population -- again, possibly because the number of women with lung cancer in the study was so small, according to the authors.

The findings suggest that “there may be additional benefits for taking (tamoxifen), particularly for breast cancer patients who are also at risk of lung cancer,” Dr. Elisabetta Rapiti, another of the study’s authors from the University of Geneva, told Reuters Health in an e-mail.

“The body of evidence seems to be leaning toward a real association between anti-estrogens and improved lung cancer outcome,” she said. In the future it’s possible that anti-estrogens could be used to treat lung cancer, she added, “opening a major new potential therapy for this very difficult disease.”

The nature of the study means the authors cannot prove that taking tamoxifen is what protected women from dying of lung cancer. More research is needed, they caution, before tamoxifen will be prescribed solely for the purpose of preventing death from lung cancer.

“I don’t think this is conclusive enough to say that (tamoxifen) helps one way or another” in regards to lung cancer, Ganti said. That, he said, “is mostly an intriguing research question. It’s not ready for clinical primetime yet.”

SOURCE: Cancer, online January 24, 2011.