Cumulative progestin dose was associated with overall (HR 1.66; 95% CI 1.52–1.82), luminal A-like (HR 1.87; 95% CI 1.65–2.12), luminal B-like (HR 1.60; 95% CI 1.30–1.97), and HER2-enriched (HR 1.79; 95% CI 1.08–2.98 for > 2 g NETA equivalence) breast cancer. Here, ERBB2 is linked to breast cancer.