SPDL1 and renal cell carcinoma: Although researchers have found that both immune and tumour cells can be sources of sPD-L1 [47, 48], no significant correlation of sPD-L1 with tumour PD-L1 expression was determined in patients with HCC, pancreatic cancer, diffuse large B-cell lymphomas and renal cell carcinomas [49–52], which is in line with our IHC results.