Alcohol and Obesity Raise Risk of Breast Cancer Recurrence
San Antonio, TX — For women with breast cancer, alcohol consumption and obesity herald a poorer prognosis, according to studies presented at the 32nd Annual San Antonio Breast Cancer Symposium. In one of the few studies to evaluate the role of alcohol in breast cancer outcomes, consumption of just a half drink per day—or two to three per week—raised the risk of recurrence by 39% (SABCS Abstract 17). In a second study of nearly 19,000 women, body mass index (BMI) ≥25 increased the risk of distant metastasis by approximately 45% (SABCS Abstract 18), speakers reported.
Alcohol consumption has been found in several studies to raise the risk of developing breast cancer, but conflicting findings have been reported for its role in survival after a breast cancer diagnosis, said Marilyn Kwan, PhD, of the Division of Research at Kaiser Permanente, Oakland, California. The LACE study prospectively examined 1898 survivors of early stage breast cancer diagnosed from 1997 to 2000. Alcohol consumption was assessed by food frequency questionnaire an average of 2 years after diagnosis. A standard drink was defined as 13.7 g (0.6 oz) of alcohol. Half the subjects reported some alcohol use, primarily wine (90%), followed by liquor (43%) and beer (36%). The women reporting alcohol use tended to be younger, white, well-educated and former or current smokers.
“We found that consuming alcohol may negatively affect breast cancer prognosis, especially among post-menopausal women and those with estrogen receptor (ER)–positive tumors,” Dr Kwan said. Compared to little or no alcohol consumption (≤0.5 g/day), the consumption of ≥6 g/day was associated with a 34% increased risk of recurrence overall, a 51% increased risk among postmenopausal women, and a 58% increased risk among women who were overweight or obese. There was a trend toward a doubling in risk in the ER-positive subset.
Alcohol consumption was also associated with a 51% increased risk of death from breast cancer, but not from other causes, Dr Kwan said. Most increased risk was observed among wine drinkers who reported at least 2 drinks per day, which raised the risk by 37% compared to women who had no drinks.
Dr Kwan said confirmation of the findings from other large prospective trials is needed before suggesting lifestyle changes for breast cancer patients. She added, however, that “this study suggests that after a breast cancer diagnosis, women should consider limiting their consumption of alcohol.” This may especially be advisable, she added, for women who are postmenopausal or overweight.
Obesity Linked to Earlier Deaths
Obesity was also implicated in poorer outcomes in a study from Denmark that included 53,816 women treated for early breast cancer between 1977 and 2006. Long-term follow-up data were available for 18,967 women.
Compared to patients with a BMI <25, those with a higher BMI were older, most often postmenopausal, had larger tumors and more grade III tumors. They also had more lymph nodes removed, more positive nodes, and more nodes with invasion into deep fascia.
By univariate analysis, the risk of a loco-regional recurrence was not related to BMI. Risk of distant metastases, however, increased with increasing BMI after 3 years of follow-up, and risk of dying from breast cancer remained elevated for obese women through 30 years of observation, reported Marianne Ewertz, MD, of the University of Southern Denmark.
“After adjustments for the effects of other prognostic factors, patients with a BMI >25 had a 42% to 46% increased risk of developing distant metastases within 10 years, and a 26% to 38% increased risk of dying from breast cancer 10 or more years after diagnosis,” she reported.
“Within the first 10 years of follow-up, chemotherapy and endocrine treatments were equally effective in lean and obese patients, but after 10 or more years the treatment effect did not last in the obese patients, who had a poorer survival,” she said. “Adjuvant treatment seems to lose its effect sooner in the obese.”
Michelle Holmes, MD, of Brigham and Women’s Hospital, Boston, discussed the findings and praised the investigators for conducting well-designed studies to shed light on these issues. “While these are not randomized controlled trials, such trials are unlikely to be conducted on lifestyle factors, and these two studies are as good as it gets,” she said.
The LACE study has the advantage of being based on an HMO, which offers excellent follow-up for recurrence, she noted. The study also controlled for factors that would predispose women for better survival. The Danish obesity study is the largest study and the one with the longest follow-up (30 years), she said. “It allows for a detailed look at subgroups, and confirms what others have reported—that there is an increased risk of breast cancer death for heavy women with breast cancer.”