SAN ANTONIO — Women who were moderate to heavy drinkers had a 1.3-fold increase in breast cancer recurrence, compared with those who abstained or drank only minimally, according to a study presented at the San Antonio Breast Cancer Symposium.
The highest risk was seen among the heaviest drinkers and overweight and/or post-menopausal survivors.
Researchers from Kaiser Permanente in Oakland, Calif. prospectively followed 1,897 women for 8 years following their diagnoses with early-stage breast cancer, studying lifestyle factors that might be associated with recurrence or death, either from cancer or other causes.
About half the cohort reported drinking alcohol. Ninety percent drank wine, 43% drank liquor, and 36% drank beer, said Marilyn L. Kwan, Ph.D., a research scientist with the large Northern California HMO.
In all, 18% of the cohort experienced a recurrence, and 17% of the cohort died, reported Dr. Kwan. Slightly more than half of the women who died succumbed to breast cancer, while 43% died from other causes.
Women who drank alcohol tended to be younger, thinner, better educated, and white, but statisticians accounted for these factors in their analysis.
After adjustment, survivors who drank at least the equivalent of 3–4 drinks per week (about a half drink per day) were 1.3 times more likely to have a recurrence of their cancer, compared with those who either did not drink or drank less than an average of 0.5 grams of alcohol per day. The results followed a positive dose-response curve, indicating that the more women drank, the more likely they were to experience a recurrence.
Women who drank less than 6 grams of alcohol per day (about a half-glass) had no increased recurrence risk.
When researchers examined subgroups of survivors, they found a 1.5-fold elevated risk among post-menopausal women, but no elevated risk among pre-menopausal women and a 1.58-fold increase in risk among overweight and obese women but no increase among normal-weight women.
Whether a survivor's breast cancer was estrogen-receptor positive or negative had no influence on her risk for recurrence if she drank alcohol.
The risk of death from breast cancer was elevated 1.5-fold among survivors who drank a mean of a half-glass of alcohol per day or more.
There was no association with death from all causes, and even a suggestion of survival protection among moderate to heavy drinkers, likely capturing the well-known cardiovascular benefits of modest alcohol consumption. Thus, the results leave unanswered the question of whether some women with breast cancer might ultimately benefit in terms of survival from modest alcohol consumption, particularly now that many women live for decades following a diagnosis.
“Our message to women with breast cancer may need to be as nuanced as our message to women without breast cancer,” said Dr. Michelle D. Holmes of the Dana-Farber/Harvard Cancer Center in Boston.
“Our results are consistent with alcohol's effect on increasing the risk of primary breast cancer,” Dr. Kwan said. “We do need the confirmation of a large, prospective study in breast cancer survivors before we can make any [definitive] lifestyle recommendations.”
Based on the signals offered in the study, however, women “should possibly consider limiting” their use of alcohol after a breast cancer diagnosis, realizing that the highest risk appears to be conferred on post-menopausal women and those who are overweight or obese, she said.