As for the different cancer types, the incidences of the fatal adverse event caused by HER2-targeted ADCs in breast cancer patients and gastric cancer patients were determined as 0.66% (95% CrI, 0.18–1.24%, τ = 0.006) and 2.01%(95%CrI,0–4.41%, τ = 0.089), respectively. Here, ERBB2 is linked to breast cancer.