In order to better construct the prognostic signature related to the molecular typing of the PD-1/PD-L1 pathway, the breast cancer samples with prognostic follow-up time greater than 0 in the TCGA database were randomly divided into the training set (Supplementary Table S4) and the internal test set (Supplementary Table S5) according to the ratio of 7:3. Here, PDCD1 is linked to breast cancer.