If the link bears out in future studies, giving tamoxifen for lung cancer may become another option for doctors, the researchers say.
The team of Swiss and French researchers followed more than 6,000 women diagnosed with breast cancer between 1980 and 2003. The researchers found that women on tamoxifen for their breast cancer who also contracted lung cancer were 87% less likely to die from the lung cancer than women who weren't on tamoxifen.
"A reduction of 87% is definitely more than modest," Elisabetta Rapiti, MD, senior epidemiologist at the Geneva Cancer Registry, tells WebMD in an email interview.
The study is published online in the journal Cancer.
Tamoxifen for Lung Cancer: The Back Story
"We have seen in the laboratory that estrogens can stimulate the growth and proliferation of lung cancer cells," she says.
So, it would follow that the tamoxifen, an “anti-estrogen,” may work against lung cancer.
"Our findings are quite new and exciting, as they are the first to document such a strong association between the use of tamoxifen and reduced mortality of lung cancer," she says.
The work builds on earlier studies, as far back as the late 1980s, that found evidence that estrogen may be involved in the development of lung cancer, she says, especially adenocarcinomas.
The adenocarcinomas occur in smokers and nonsmokers and are more common in women than in men, the American Cancer Society says. The tumors are usually found in the outer region of the lung and account for about 40% of all lung cancers.
Tamoxifen for Lung Cancer: Study Details
Rapiti's team found that 40 women in the study -- out of a total of 6,655 -- contracted lung cancer during the follow-up, which lasted until December 2007. Although 46% of the women were prescribed tamoxifen or other anti-estrogen drugs to treat their breast cancer, 54% were not.
The researchers looked at which women had been treated with anti-estrogen drugs and didn't find a difference between the groups when it came to getting lung cancer.
But fewer women with lung cancer on the anti-estrogen drugs died than what would be expected in the general population. They found 87% fewer cases of death from lung cancer in women on the anti-estrogen drugs than in the population at large.
The women not treated with anti-estrogen drugs had the same risk of dying from lung cancer as other women.
Tamoxifen for Lung Cancer: Second View
The study finding ''makes sense based on what we have seen in the lab," says Carolyn M. Klinge, PhD, professor of biochemistry and molecular biology at the University of Louisville, who reviewed the study findings for WebMD. She has done basic research in the laboratory on lung cancer cells.
In her research, she found that lung adenocarcinoma cells sometimes grew when treated with estradiol, a potent natural estrogen, and sometimes did not.
On looking further, she discovered that the cells that originated from women grew, but those from men did not.
Tamoxifen for Lung Cancer: The Future
''The question now is not whether there is an effect [of tamoxifen on lung cancer] but just how big it really is," Rapiti says.
The value of tamoxifen for lung cancer treatment will probably be in a select group of patients, she says.