ERBB2 and head and neck cancer: In HER2-positive breast cancer patients, PD-L1 expression by tumour cell was associated with favourable prognosis while PD-L1 expression on TILs was not.31 In contrast, PD-L1 expression by TILs but not by tumour cell was associated with favourable prognosis in head and neck cancer patients.32 In the present study, PD-L1 and PD-L2 expression by TILs had a tendency of positive prognostic role while expression by tumour cells did not.