Baglia ML, et al. - In this population-based case-case study, researchers evaluated the association between alcohol, smoking, and and risk of different subtypes of breast cancer, such as triple-negative (TN) and human epidermal growth factor receptor 2-overexpressing (H2E) breast cancers, which may have different etiologies from more common luminal (estrogen receptor [ER+]) breast cancers. They evaluated the associations among 909 ER+, 1,290 TN, and 489 H2E breast cancer patients, with ER+ breast cancer patients as the reference group using polytomous regression. Outcomes indicated a lower risk of H2E breast cancer in correlation to alcohol intake relative to ER+ breast cancer. This suggests that breast cancer subtypes differ in breast cancer etiology.