Table 1.

Characteristics of included studies.

Reference	Study type	Study region	Ethnicity	Sample size	Treatment	Evaluated cells	Cutoff value for PD-L1	Positive PD-L1 (%)	Median follow-up (months)	Survival
Skala et al. (24)	RC	USA	Caucasus	149	RNU: all; AC: 17 (11.4%); NC: 18 (12.1%); immunotherapy: N.R.	Tumor cells (PD-L1)	≥5%	23.5	24.8	CSS
Krabbe et al. (15)	RC	USA	Caucasus	423 (high-grade UTUC)	RNU: all; AC, NC, immunotherapy: none	Tumor-infiltrating lymphocytes (PD-1) and tumor cells (PD-L1)	≥1%	26.2	37.0	OS, CSS, RFS
Zhang et al. (13)	RC	China	Asian	162	RNU: all; AC, NC: N.R. immunotherapy: none	PD-L1 in tumor cells and TIMCs	≥5%	12.3	79.0	CSS
Miyama et al. (16)	RC	Japan	Asian	271	RNU: all; AC, NC: N.R. immunotherapy: N.R.	Circulating platelets and tumor cells (PD-L1)	≥5%	11.0	52.0	OS, MFS
Arriola et al. (23)	RC	USA	Caucasus	72	RNU: all; AC, immunotherapy: N.R.; NC: none	Tumor-infiltrating lymphocytes (PD-1) and tumor cells (PD-L1)	≥1%	37.5	98.7	OS, CSS
Wang et al. (25)	RC	China	Asian	88	RNU: all; AC: 8 (9.1%); NC, immunotherapy: N.R.	Tumor cells (PD-L1/2)	≥1%	23.9	23.0	OS, CSS
Nukui et al. (17)	RC	Japan	Asian	79	RNU: all; AC: 41 (51.9%); NC, immunotherapy: N.R.	Tumor cells and TILs (PD-L1)	≥5%	39.2	45.0	OS, CSS
Kim et al. (14)	RC	Korea	Asian	162 (non-metastatic UTUC)	RNU: all; AC: 72 (44.4%); NC: none; immunotherapy: N.R.	Tumor cells (PD-L1)	≥5%	3.086	53.4	OS, CSS

RC, retrospective cohort study; RNU, radical nephroureterectomy; AC, adjuvant chemotherapy; NC, neoadjuvant chemotherapy; OS, overall survival; CSS, cancer-specific survival; IHC, immunohistochemistry staining; MFS, metastasis-free survival; RFS, recurrence-free survival; N.R., not reported.