Research consistently has shown that regularly drinking alcohol increases a woman's risk of hormone-receptor-positive invasive breast cancer. Results from a study agree with the earlier research and also show that drinking alcohol increases the risk of lobular -- but not ductal -- hormone-receptor-positive invasive breast cancer.
Invasive lobular carcinoma (ILC) is breast cancer that begins in the milk-producing lobules that empty into ducts that carry milk to the nipple. ILC is the second most common type of invasive breast cancer. Invasive ductal carcinoma (IDC), which begins in the ducts that carry milk from the lobules to the nipple, is the most common type of invasive breast cancer.
The very large Women's Health Initiative (WHI) study allowed researchers to look at the drinking habits and health histories of nearly 88,000 women. Women joined the WHI from 1993 to 1998. Each woman reported her lifetime drinking habits, including the amount and type of alcohol she drank. During the follow-up period that ended in September 2005, 2,944 of the women were diagnosed with invasive breast cancer. The researchers compared the drinking habits of women diagnosed with invasive breast cancer to the drinking habits of women who didn't develop invasive breast cancer.
- Just one drink a day doubled the risk of hormone-receptor-positive invasive breast cancer; the more alcohol a woman consumed, the more likely she was to develop hormone-receptor-positive breast cancer.
- Drinking alcohol increased the risk of lobular, but not ductal, hormone-receptor-positive invasive breast cancer.
- The risk of lobular hormone-receptor-positive invasive breast cancer was 63% greater in women who drank any amount of alcohol compared to women who never drank. This difference was significant, which means it was likely because of drinking and not just due to chance.
- The risk of ductal hormone-receptor-positive invasive breast cancer was 18% greater in women drank alcohol compared to women who never drank. This difference wasn't significant, which means it could have been due to chance and not because of drinking.
- Drinking alcohol didn't increase the risk of hormone-receptor-negative invasive breast cancer.
It's not clear why alcohol affected the risk of lobular and ductal hormone-receptor-positive breast cancer differently.
Estrogen can cause hormone-receptor-positive breast cancer to grow and alcohol can increase estrogen levels in a woman's body. This estrogen increase may be why there is a link between drinking alcohol and breast cancer.
The results of this study support the results of many other large studies linking alcohol and breast cancer risk. If you want to do everything you can to lower your risk of breast cancer, limiting how much alcohol you drink makes sense.
To learn more about how you can keep your risk of breast cancer as low as it can be, visit the Breastcancer.org Lower Your Risk section.