Doctors have suspected that the hormone estrogen, which can cause hormone-receptor-positive breast cancers to grow, also may affect lung cancers. A large Swiss study found that women treated with hormonal therapy for breast cancer were 87% less likely to die from lung cancer compared to the average person's risk of dying from lung cancer.
The researchers looked at the medical records of 6,655 women diagnosed with breast cancer between 1980 and 2003. The women's medical records were part of the Geneva Cancer Registry. About 46% of the women got hormonal therapy (called anti-estrogen therapy in the article) to treat breast cancer. Most of the women took tamoxifen because the aromatase inhibitors weren't available when many of the women were treated.
Forty of the 6,655 women also were diagnosed with lung cancer 6 months or more after being diagnosed with breast cancer. Although smoking is strongly linked to lung cancer risk, more than 60% of these 40 women had never smoked. Looking at all the women in the study, the women diagnosed with lung cancer were no more likely to have a history of smoking than the women who weren't diagnosed with lung cancer. Still, the researchers didn't have complete smoking histories for all of the women.
The researchers compared lung cancer risk and survival in the two groups of women: those who took hormonal therapy to treat breast cancer and those who didn't.
Women who got hormonal therapy treatment for breast cancer were 37% less likely to be diagnosed with lung cancer compared to the average person. This difference wasn't statistically significant, which means that it could have been due to chance and not because the women took hormonal therapy.
Still, compared to the average person, women who got hormonal therapy treatment for breast cancer were 87% less likely to die from lung cancer.
Women who didn't get hormonal therapy had about the same risk of being diagnosed with lung cancer as the average person.
Among the 40 women also diagnosed with lung cancer, women treated with hormonal therapy for breast cancer were 80% less likely to die from the lung cancer compared to women who didn't get hormonal therapy. Women diagnosed with lung cancer and breast cancer who weren't treated with hormonal therapy were as likely to die of lung cancer as the average person diagnosed with lung cancer.
These results suggest that estrogen may play a role in the development, growth, and spread of lung cancer. Some lung cancer cells have hormone receptors and hormones such as estrogen are known to play a role in the normal growth and development of lung tissue. More information about the possible link between estrogen and lung cancer could help doctors better understand how estrogen fuels breast cancer and might lead to better prevention strategies and new treatment options for breast, lung, and other cancers.
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