ERBB2 and triple-negative breast carcinoma: APOBEC3-dominant signature was found in 15.7% and 28.7% of primary and metastatic hormone receptor (HR) positive (HR+)/HER2−, 18.5% and 33.1% of primary and metastatic HR+/HER2+, 30.2% and 20.6% of primary and metastatic HR−/HER2+ and 8.4% and 16.9% of primary and metastatic triple-negative breast cancers (TNBC) (Fig. 1c), respectively.