Files of breast cancer patients attending breast cancer clinic at Ain Shams University Clinical oncology and nuclear medicine department will be viewed by the investigator and those who fit the selection criteria will be included in the study. Tru-cut or core tissue biopsies obtained from the participants for initial diagnosis will be collected and PD-L1 testing will be done on the specimens. Scoring of PD-L1 will be done using Combined positive score (CPS) score. PD-L1 expression will be evaluated among Her-2 positive and triple negative subtypes and will be correlated with pathological complete response after reviewing the postoperative pathology results of the patients.
Patients with Her-2 positive and triple negative breast cancer who received neoadjuvant chemotherapy will be included in the study. Paraffin blocks of preoperative core or tru-cut biopsies of the participants will be collected and tested for programmed death-ligand 1 (PD-L1) expression. The variation of PD-L1 expression among different breast cancer subtypes will be evaluated and the investigator will correlate between PD-L1 expression and pathological complete response to neoadjuvant systemic therapy.