Large studies have shown that using hormone replacement therapy (HRT) -- especially combination HRT containing estrogen AND progesterone -- increases breast cancer risk. Other studies have suggested a link between HRT use and lung cancer, especially among women with a history of smoking.
A large study found that women who used combination HRT were up to 48% more likely to develop lung cancer compared to women who never used HRT or used estrogen-only HRT.
The researchers looked at the medical records of 36,588 women for 6 years to see if there were any links between HRT use and lung cancer risk. The women in the study were age 50 to 76 and were in early menopause (perimenopause), actual menopause, or had gone through menopause. The women were part of the VITAL (Vitamins and Lifestyle) study, which was looking at links between nutritional supplements and breast cancer risk.
The researchers looked at whether a woman used HRT, the type of HRT, and how long it was taken. About 66% of the women reported using HRT in the past and/or during the study. About 66% of the women also had a history of cigarette smoking. Also, about 66% of the women had a personal or family history of cancer. During the 6 years the women were followed, 344 women were diagnosed with lung cancer.
Combination HRT use was associated with a higher risk of lung cancer risk. The amount of risk increase was linked to how long a woman used HRT. Compared to women who never used HRT:
- women who used combination HRT for 10 years or more had a 48% higher risk of lung cancer
- women who used combination HRT for 9 years or fewer had a 27% higher risk of lung cancer; still, this increase in risk wasn't statistically significant, which means it could have been due to chance and not because of HRT use
The researchers also found:
- women who used combination HRT and developed lung cancer were more likely to have more advanced lung cancer at diagnosis compared to women who developed lung cancer but never used combination HRT
- women who used estrogen-only HRT during or after menopause had the same lung cancer risk as women who never used HRT
- combination HRT use increased lung cancer risk no matter if a woman smoked or not
Menopausal side effects can dramatically reduce quality of life for some women. These women have to weigh the benefits of HRT against the risks. Those risks include increased breast cancer risk and, as the study reviewed here suggests, increased lung cancer risk.
If you're having severe hot flashes or other menopausal side effects and are considering HRT, talk to your doctor about all of your options. Ask how you can minimize your cancer risk AND relieve your symptoms. Be sure to discuss the pros and cons of different types of HRT. Other research strongly suggests that estrogen-only HRT appears to increase breast cancer risk less than combination HRT. The study reviewed here suggests that estrogen-only HRT doesn't increase lung cancer risk. If you do decide to take HRT, ask if you can take a low-dose formula and try to take it for the shortest time possible. Remember that smoking is a major risk factor for lung cancer and also may be a risk factor for breast cancer. If you don't smoke, don't start. If you do smoke, take steps to quit.
Learn more about more about menopause and ways to manage side effects in the Breastcancer.org Managing Menopausal Symptoms section.