Women who consumed alcohol between menarche and first pregnancy carried a 10% increased risk for breast cancer, according to study results.
The researchers aimed to investigate the effect of alcohol consumption on breast cancer or proliferative benign breast disease risk in the interval between menarche and first full-term pregnancy.
The analysis included data from 91,005 parous women from the Nurses’ Health Study II. Eligibility criteria included no previous history of cancer. Women were asked about alcohol consumption in 1989. Follow-up continued through June 2009 to gauge breast cancer risk.
The analysis also included a subset of 60,093 women with no history of benign breast disease or breast cancer in 1991. This cohort was followed through June 30, 2001.
Review of histology results indicated that 1,609 cases of breast cancer and 970 proliferative benign breast disease cases developed. The researchers reported that breast cancer risk was increased among women who consumed alcohol between menarche and first pregnancy (RR=1.11 per 10g/day intake; 95% CI, 1.00-1.23). Proliferative benign breast disease also was increased among women who consumed alcohol in this interval (RR=1.16 per 10g/day intake; 95% CI, 1.02-1.32).
Breast cancer risk was elevated among women who drank after first pregnancy (RR=1.09 per 10g/day intake; 95% CI, 0.96-1.23). No similar risk for benign breast disease was observed among women who drank during this time period.
As the interval between first menstruation and first pregnancy increased, the association between drinking before first pregnancy and breast neoplasia increased.
The work was supported by the NCI and NIH.