, an analysis of data from a prospective cohort study suggests.
Kaiser Permanente
Dr. Marilyn Kwan
The study appears to show that drinking up to one serving of alcohol daily, including wine, beer, and liquor, was not associated with any specific outcomes after breast cancer diagnosis. The authors say these findings could have implications for developing more specific guidelines on alcohol use as it relates to the prevention of death and recurrence for cancer survivors.
Among 3,659 women followed for a mean of 11.2 years after a breast cancer diagnosis, overall alcohol consumption in the months before and up to 6 months after diagnosis was not associated with recurrence or mortality after adjusting for numerous factors such as age at diagnosis, cancer stage, socioeconomic details, smoking history, and preexisting conditions.
However, women with obesity (body mass index of 30 kg/m2 or greater) had a lower risk of mortality with increasing alcohol consumption for occasional drinking of 2 or more alcohol servings per week (hazard ratio, 0.71), and regular drinking of at least one alcohol serving daily (HR, 0.77), in a dose-response manner, Marilyn L. Kwan, PhD, and colleagues found.
Dr. Kwan is a senior research scientist at Kaiser Permanente Northern California Division of Research, Oakland.
Women with BMI less than 30 kg/m2 did not have a higher risk of mortality but a nonsignificant increase in the risk of recurrence was observed for those who consumed alcohol occasionally (HR, 1.29) and regularly (HR, 1.19), the investigators reported.
The findings were published online in Cancer.
Women included in the current study were participants in the Pathways Study and were diagnosed with stage I-IV breast cancer between 2003 and 2015. During follow-up, 524 recurrences and 834 deaths occurred, including 369 breast cancer-specific deaths, 314 cardiovascular disease-specific deaths, and 151 deaths from other health problems.
Alcohol consumption was assessed for the 6 months prior to cohort entry, which occurred at an average of about 2 months after diagnosis, as well as 6 months later – at an average of about 8 months after diagnosis – using a food-frequency questionnaire.
Compared with nondrinkers (36.9%), drinkers were more likely younger, more educated, and current or past smokers, the investigators noted.
“This profile appears counterintuitive yet might reflect a healthier lifestyle contributing to better overall survival. Furthermore, higher levels of alcohol consumption could lead to improvement in insulin sensitivity and reduction in insulin-like growth factor-1,” they speculated, noting that reduced fasting insulin concentrations and lower insulin-like growth factor-1 levels are linked with a decreased risk of type 2 diabetes, cardiovascular disease, and cancer.
“Many women with a history of breast cancer are interested in how to improve their prognosis and survival by making lifestyle changes after diagnosis,” they wrote, explaining the rationale for the study. “Current cancer prevention guidelines recommend avoiding alcohol intake or limiting consumption to no more than one drink per day for women. However, no specific guideline exists for cancer survivors other than following the cancer prevention guidelines to reduce the risk of a second cancer.”
High-quality studies on the impact of alcohol consumption on breast cancer prognosis are lacking, they added.
“Given that consuming alcohol is a potentially modifiable lifestyle factor after breast cancer diagnosis, further confirmation is warranted in other large prospective studies of breast cancer survivors with detailed exposure assessment and focus on body size,” they concluded.
The group is the first to report this finding in obese women, and they “strongly believe more research is needed to see if the same association is seen in other studies,” Dr. Kwan told this news organization.
“After a cancer diagnosis, many patients are motivated to make lifestyle changes,” she said. “That often includes adding exercise to their daily routine and eating a healthier diet. Our study findings suggest that doctors can tell patients that having up to a glass of alcohol a day is not likely to increase their risk of a breast cancer recurrence.”
This study was funded by the National Cancer Institute. The authors reported having no disclosures.