In order to figure out whether the observed CD3E + KRT8 + T cells were patient-specific or generally existed, we evaluated the percentage of CD3E + KRT8 + T cells across 19 samples, including 6 in-house MBC samples, 2 in-house FBC samples, and 11 FBC samples from Wu et al. It turned out that 17/19 breast cancer samples had CD3E + KRT8 + T cells with different degrees, ranging from 0.2% to 83.1% (Supplementary Fig. 14a). Here, KRT8 is linked to breast cancer.