GPT and anemia (phenotype): The most common adverse events of any grade for T‐DM1 included thrombocytopenia (RR 7.14, 95% CI 4.13–12.36) and increased alanine‐transaminase (ALT) (RR 2.04, 95% CI 1.43–2.91), for T‐DXd were nausea (RR 2.39, 95% CI 1.90–3.00) and anemia (RR 1.55, 95% CI 1.27–1.90), while for SG were neutropenia (RR 1.30, 95% CI 1.14–1.49), diarrhea (RR 3.62, 95% CI 2.97–4.42) and nausea (RR1.90, 95% CI 1.65–2.19).