ERBB2 and breast cancer: Gallen classification of BC, the subtype frequency was as follows: the most common was luminal A with 409 cases (34%), followed by HER2-enriched with 169 cases (14%), triple-negative BC with 153 cases (12.7%), TPBC with 124 cases (10.3%), and the least common was luminal B, with 81 cases (6.7%).