Alcohol consumption may not increase risk for breast cancer recurrence
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Key takeaways:
- Women with BMI 30 kg/m² exhibited lower risk for overall mortality with increasing levels of alcohol consumption.
- Those with BMI < 30 kg/m² appeared at higher risk for recurrence with occasional drinking and regular drinking.
Alcohol consumption did not appear associated with increased risk for breast cancer recurrence or mortality, according to study results published in Cancer.
However, results varied by BMI. Those with higher BMI exhibited lower risk for overall mortality with increasing alcohol consumption, and researchers noted a possible higher risk for recurrence among nonobese women.
Rationale and methodology
“We were aware that oncologists are often asked by breast cancer survivors about whether it is safe to drink alcohol,” Marilyn L. Kwan, PhD, senior research scientist in the division of research at Kaiser Permanente Northern California, told Healio. “We were also aware that many of the studies that have examined alcohol use and breast cancer have had conflicting results, and many were focused on alcohol use before breast cancer.”
The prospective Pathways Study — one of the largest U.S. studies to follow breast cancer survivors and track the relationship between lifestyle changes and outcomes — included 4,504 women diagnosed with invasive breast cancer between 2005 and 2013 at Kaiser Permanente Northern California.
“We believed it would be possible for us to use data that we have collected in our study to provide breast cancer survivors with information they could use to make decisions about alcohol use,” Kwan said.
Researchers examined the association between short‐term alcohol intake and recurrence or mortality among 3,659 women. They used a food-frequency questionnaire to assess alcohol consumption within the previous 6 months and again 6 months later.
Primary endpoints included breast cancer recurrence, as well as death due to breast cancer, cardiovascular disease and all causes.
Median follow-up was 11.2 years.
Findings
Overall, researchers observed 524 breast cancer recurrences and 834 deaths (breast cancer-specific deaths, n = 369; cardiovascular disease-specific deaths, n = 314; other, n = 151).
Compared with nondrinkers (36.9%), drinkers appeared more likely to be younger, to be current or past smokers, and to have higher education levels.
Researchers observed no association between recurrence or mortality.
Women with BMI 30 kg/m² exhibited lower risk for overall mortality with increasing alcohol consumption (HR for occasional drinking = 0.71; 95% CI, 0.54-0.94; HR for regular drinking = 0.77; 95% CI, 0.56-1.08) near the time of breast cancer diagnosis and 6 months later, with researchers observing this result in a dose-response manner (P < .05).
“It’s not clear how to interpret this finding, although the women with obesity possibly had a healthier lifestyle, as they exercised more,” Kwan said. “We are the first group to make this finding in obese women and we strongly believe more research is needed to see if the same association is seen in other studies.”
Women with BMI less than 30 kg/m² did not appear at higher risk for mortality. However, they did appear at greater risk for recurrence with occasional drinking (HR = 1.29; 95% CI, 0.97-1.71) and regular drinking (HR = 1.19; 95% CI, 0.88-1.62).
Researchers acknowledged study limitations. The analysis did not examine patterns of change in postdiagnosis alcohol consumption because investigators examined separate effects of peri-diagnosis and up to 6 months postdiagnosis exposure on outcomes. In addition, the data did not allow researchers to determine the timing of alcohol consumption during the day or week, the quantity consumed per drinking occasion, or whether alcohol was consumed alone or with a meal.
Implications
The findings suggest that physicians — in the absence of specific guidelines for survivors — physicians can tell patients to follow guidelines for breast cancer prevention, Kwan told Healio. These guidelines suggest women do not drink more than one glass of alcohol per day.
“Guidelines for preventing cancer risk recommend that women have no more than one alcoholic drink per day,” she said. “Currently, there are no guidelines for breast cancer survivors on alcohol use. After a cancer diagnosis, many patients are motivated to make lifestyle changes that often include adding exercise to their daily routine and eating a healthier diet.”
References:
- Drinking alcohol not likely to increase risk of a breast cancer recurrence (press release). Available at: https://www.eurekalert.org/news-releases/998113. Published Aug. 9, 2023. Accessed Aug. 17, 2023.
- Kwan ML, et al. Cancer. 2023;doi:10.1002/cncr.34972.
For more information:
Marilyn L. Kwan, PhD, can be reached at marilyn.l.kwan@kp.org.
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