PDCD1 and breast carcinoma: The relationship between EBV reactivation and the PD-1/PD-L1 pathway has been quite well documented in the course of many cancers, including gastric cancer [47,48], breast cancer [49], and nasopharyngeal carcinoma [50], where EBV reactivation was associated with worsening of the tested clinical parameters and a worse prognosis of patients.