CD274 and differentiated thyroid carcinoma: A previous study reported that the increased cytoplasmic PD-L1 in all four stages of papillary thyroid carcinoma patients was correlated with a greater risk of recurrence and a poor prognosis, but increased membrane PD-L1 significantly correlated with a greater risk of metastasis or death in stage IV patients [43], supporting that both intracellular and surface PD-L1 are playing an important role in tumour development and metastasis thus need to be considered together in the therapy.