Alcohol increases the risk of lobular and hormone receptor-positive breast cancer, but not necessarily invasive ductal carcinomas, according to a study published Aug. 23 online in The Journal of the National Cancer Institute.
Although alcohol intake is an established risk factor for breast cancer overall, few studies have looked at the relationship between alcohol use and breast cancer risk by subtype of breast cancer. While some studies have shown alcohol use is more strongly related to risk of hormone receptor-positive breast cancer, not many have looked at breast cancer risk by whether a tumor is in the milk ducts (ductal) or in the milk-producing lobules (lobular).
To understand how alcohol may influence these sub-types of breast cancer, Drs. Chris Li and Ross Prentice of the Public Health Sciences Division and colleagues conducted an observational study of a subset of patients in the Women’s Health Initiative study, conducted between 1993 and 1998, which included more than 87,000 50- to 79-year-old postmenopausal women.
The researchers looked data from the nearly 3,000 women in the WHI study who developed invasive breast cancer: tumor subtypes and hormone status, alcohol consumption, demographic and lifestyle characteristics, family disease history and reproductive history.
The researchers found that alcohol use is more strongly related to the risk of lobular carcinoma than ductal carcinoma, and more strongly related to hormone-receptor-positive breast cancer than hormone-receptor-negative breast cancer. These results confirm previous findings of an association of alcohol consumption with hormone-positive breast cancer risk, as well as three previous case control studies that identified a stronger association of alcohol with lobular carcinoma. The risks observed did not vary by the type of alcohol women consumed.
“We found that women who drank one or more drinks per day had about double the risk of lobular type breast cancer, but no increase in their risk of ductal type breast cancer,” the authors wrote. Ductal cancer is much more common than lobular cancer, accounting for about 70 percent of all breast cancers. Lobular cancer accounts for only about 10 percent to 15 percent of cases.
The study’s primary limitation, the authors said, is that alcohol usage was only assessed at the beginning of the study, so the researchers had no information on past or subsequent alcohol consumption.
A National Heart, Lung and Blood Institute grant supported the work.
[Adapted from a JNCI news release]