PECAM1 and neoplasm: CD96 staining was also detected in tumor‐infiltrating CD8+ T cells but was only minimally detected in CD31+ endothelial cells or α‐SMA+ fibroblasts in patients with BC (Figure S1A, Supporting Information), which is consistent with the results of previous studies.[17] Importantly, the application of optimal cutoff points, as determined using X‐tile statistical software, revealed that 38.3% of patients with BC expressed high levels of CD96 (Figure 1B,C), and that such high tumoral CD96 expression was associated with worse disease‐free survival (DFS) and overall survival (OS) (Figure 1D).