A comparable overall discordance rate was noted between HER2-positive (8.7% 95% CI 4.8–13.7, n = 149, I2 = 0%) and TNBC (8.8%, 95% CI 4.9–13.7, n = 151, I2 = 0%) breast cancer patients (p = 0.557 for the comparison among the three subtypes). Here, ERBB2 is linked to breast cancer.