ERBB2 and breast cancer: In women with healthy weight, there was significant heterogeneity in associations between current ET use and different breast cancer subtypes (P < .001 for heterogeneity), with a higher occurrence of luminal A–like tumors (OR, 1.16 [95% CI, 1.01-1.32]) and a lower occurrence of ERBB2-enriched–like (OR, 0.58 [95% CI, 0.38-0.89]) and triple-negative (OR, 0.73 [95% CI, 0.54-0.97]) tumors (Figure 2 and eTables 5 and 20 in Supplement 1).