CD274 and breast cancer: Whereas TIL PD-L1 staining showed no statistically significant association with clinical-pathological features and patients survival, in line with what already described in the literature for other BC subtypes [10], we showed a direct statistically significant association between the expression of tumor PD-L1 and the proliferation index, and an inverse correlation between the expression of the protein and menopause, the presence of lymph node metastasis and recurrence.