Alcohol consumption is a well-established risk factor for breast cancer. As few as three alcoholic drinks per week (including red wine) have been shown to increase risk. The increased risk conferred by drinking can begin as early as the teenage years—one study reported that girls who consume alcohol during adolescence are more likely to develop proliferative benign breast disease and that this risk increases in proportion with the amount of alcohol they consume. Drinking before first birth has been linked to later breast cancer in several studies. Alcohol consumption appears to preferentially heighten breast cancer risk among women already at high risk for the disease. Alcohol consumption has been shown to increase risks of hormone receptor positive (ER+/PR+), HER2 overexpressing (HER2+) and lobular breast cancer. Alcohol also appears to heighten the breast cancer risk associated with using hormone replacement therapy (HRT).
In addition to being a risk factor for the development of breast cancer, high alcohol intake before diagnosis appears to have an unfavorable effect on the course of the disease. While a limited amount of alcohol consumption does not appear to increase risk of breast cancer recurrence, one prospective study reported that consuming three to four alcoholic drinks per week increased the risk of relapse, especially for postmenopausal and overweight women. Several drinks consumed over a short period of time is a more potentially harmful pattern than the same amount of alcohol consumed over a period of days. Note that consuming alcohol has been shown to interfere with the effectiveness of treatment with tamoxifen.
There are genetically derived differences between African-American women and those from other U.S. racial groups in terms of frequency, age at diagnosis, and type of breast cancer. Generally speaking, diet and lifestyle-related factors appear to affect risk similarly. However, there is some evidence that certain risk factors (such as being overweight or not breastfeeding children) influence breast cancer risk differently for women of different groups. While alcohol has been shown to increase breast cancer risk across ethnic groups in most studies, one 2016 study (see Adherence to diet, physical activity and body composition guidelines and breast cancer in the black women's health study below) reported that alcohol may be "less relevant in this population." Now a large new study has reported that African-American women who consume at least seven drinks per week are at increased risk of triple negative (ER-/PR-/HER2-) breast cancer.
Latest research links alcohol to triple negative disease among African Americans
The study referenced at the beginning of this news story was designed to investigate the association between number of alcoholic drinks consumed per week and risk of breast cancer among African American women. The study included 22,338 women in the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium, including 5,108 women with invasive breast cancer. Approximately 35% of the cancer-free controls were current drinkers at the time of interview.
Women who reported current consumption of at least 14 drinks per week were found to have 1.33 times the risk of breast cancer as light drinkers (no more than three drinks per week). Women consuming at least seven drinks per week had elevated risks of ER- (1.31 x) , PR- (1.28 x), HER2- (1.36 x) and triple negative disease (1.39 x). Alcohol consumption was also associated with elevated risks of ER+/PR+ and HER2+ breast cancer, but less so than for receptor-negative cases. The patterns of association did not appear to be influenced by age of exposure (under 30 years, 30-49, over 50 years of age). Nor did birth control pill use, smoking, or menopausal status vary the risks associated with alcohol intake. The authors conclude that African-American women who consumed seven or more drinks per week had an increased risk of breast cancer. Since alcohol intake is a modifiable risk factor for breast cancer, reduced intake among African-American women should be encouraged, according to the authors.