Alcohol consumption is an established risk factor for incident breast cancer. However, its role in breast cancer prognosis remains unclear.
We conducted an investigation of postdiagnosis alcohol consumption with recurrence and mortality among 9,329 breast cancer patients in the After Breast Cancer Pooling Project. Women were diagnosed from 1990 to 2006 with AJCC Stage I-III breast tumors from three prospective US cohorts. Alcohol intake was assessed at cohort entry (mean 2.1 years postdiagnosis) using a food frequency questionnaire. HR and 95% confidence intervals (CI) were estimated using delayed entry Cox proportional hazards models with adjustment for known prognostic factors.
After a mean follow-up of 10.3 years, 1,646 recurrences and 1,543 deaths were ascertained. 5,422 women (58%) were considered drinkers (≥0.36 g/day of alcohol, ≥0.25 drinks/week) with a median of 5.3 g/day. Overall, compared with nondrinking, regular alcohol intake (≥6.0 g/day) was not associated with risk of recurrence (HR for 6 to less than 12 g/day, 1.03; 95% CI, 0.86-1.24; HR for 12 to less than 24 g/day, 1.12; 95% CI, 0.93-1.34; HR for ≥24 g/day, 1.04; 95% CI, 0.84-1.31). However, risk varied significantly by menopausal status (P for interaction < 0.05). Postmenopausal women who regularly consumed alcohol (≥6.0 g/day) had increased risk of recurrence (HR, 1.19; 95% CI, 1.01-1.40). Alcohol intake was not associated with mortality.
Regular alcohol consumption was not associated with breast cancer recurrence and total mortality overall, yet recurrence risk was only elevated in postmenopausal women.
The association between alcohol intake and recurrence may depend on menopausal status at breast cancer diagnosis.