Jung M, et al. - Considering the significant association of immunohistochemical (IHC) staining for CK5/6, CD44, and CK20 with the prognosis of urinary bladder urothelial carcinoma and probably with its molecular characteristics, researchers investigated the IHC-based subgroups and their prognostic effects on upper tract urothelial carcinoma (UTUC), especially in non-muscle-invasive papillary UTUC. On analyzed IHC staining for CK5/6, CK20, and CD44 in 211 patients with non-muscle-invasive papillary UTUC, they identified the CK5/6^Neg, CD44^Neg, and CK20^Pos tumours as distinct high-risk subgroups which were associated with a high grade and frequent IVR. Findings thus suggest a significant association of IHC staining for CK5/6, CD44, and CK20 with the clinicopathological characteristics and prognoses of patients with non-muscle-invasive papillary UTUC.