Because one potential mechanism for alcohol's impact on breast cancer risk involves hormonal effects17, we examined the association by ER/PR status of the tumor (Table 3). For this analysis, we excluded 1620 cases with unknown ER and/or PR status. Alcohol consumption seemed to be more strongly associated with risk of ER+and//orPR+, but the p for interaction was not significant. Results were similar for ductal and lobular histology (eTable 2).
