Evidence summary: We conducted 5 meta-analyses and referred to the recommendations from relevant systematic reviews, guidelines and monographs. (1) To compare the efficacy and safety of gemcitabine and pirarubicin for the intravesical infusion chemotherapy of NMIBC, a total of 31 RCTs (32 studies)[
45-
75] were included in the meta-analysis, with a total of 2182 patients and a maximum follow-up time of 36 months. Results showed that the 1-year recurrence rate (
RR=0.58, 95%CI 0.40–0.84), 2-year recurrence rate (
RR=0.58, 95%CI 0.48–0.70) and 3-year recurrence rate (
RR=0.51, 95%CI 0.31–0.84) of gemcitabine group were lower than those of pirarubicin group, but there was no significant difference in 1-year progression rate (
RR=0.60, 95%CI 0.35–1.02) and 3-year progression rate (
RR=0.50, 95%CI 0.05–5.19) between the two groups; The recurrence risk in gemcitabine group was 0.47 times of that in pirarubicin group (
HR=0.47, 95%CI 0.25–0.89). In terms of safety, the incidence of cystitis (
RR=0.35, 95%CI 0.14–0.86), bladder irritation (
RR=0.54, 95%CI 0.44–0.65) and hematuria (
RR=0.35, 95%CI 0.23–0.52) in gemcitabine group was lower than that in pirarubicin group. There was no significant difference in the incidence of fever (
RR=0.77, 95%CI 0.33–1.79) and allergic reaction (
RR=0.44, 95%CI 0.17–1.17) between the two groups. There was no heterogeneity among the included studies for the above outcome indicators. Subgroup analysis was carried out according to the dosages and medication schemes. The results showed that the conventional dose of gemcitabine (1000 mg) produced better outcome than the conventional dose group of pirarubicin (30–50 mg) in terms of efficacy indexes (1-year, 2-year and 3-year recurrence rate) and safety indexes (cystitis, bladder irritation sign and hematuria). Under the drug regimen of immediate combined induction and maintenance instillation after TURBT operation in both groups, gemcitabine group saw better outcome than pirarubicin group in terms of efficacy indexes (1-year and 2-year recurrence rate) and safety indexes (cystitis, bladder irritation sign and hematuria) (Additional file 3: Table S1). (2) To compare the efficacy and safety of pirarubicin and hydroxycamptothecin for the intravesical infusion chemotherapy of NMIBC, a total of 14 RCTs[
68,
76-
88] were included in the meta-analysis, with a total of 1284 patients and a maximum follow-up time of 60 months. Results showed that, in terms of effectiveness, there was no significant difference between the pirarubicin group and the hydroxycamptothecin group in the 1-year recurrence rate (
RR=0.79, 95%CI 0.58–1.07), 2-year recurrence rate (
RR=0.80, 95%CI 0.61–1.05), 3-year recurrence rate (
RR=0.84, 95%CI 0.37–1.91), 4-year recurrence rate (
RR=0.92, 95%CI 0.44–1.95) and 5-year recurrence rate (
RR=0.73, 95%CI 0.43–1.23). In terms of safety, there was no difference between the two groups in the incidence of total adverse reactions (
RR=1.38, 95%CI 0.71–2.70) and hematuria (
RR=0.99, 95%CI 0.60–1.62), but the incidence of bladder irritation (
RR=1.39, 95%CI 1.14–1.70) in pirarubicin group was higher than that in hydroxycamptothecin group. Except for the indicators of total adverse reaction, there was no heterogeneity among the studies included in the above outcome indicators. Subgroup analysis was carried out according to the dosages and medication schemes. The results showed that the 2-year recurrence rate and the incidence of bladder irritation in the pirarubicin (30–50 mg) group were lower than those in the hydro-xycamptothecin (10–20 mg) group. There was no significant difference in these indicators between the two groups under different medication schemes (Additional file 3: Table S1). (3) To compare the efficacy and safety of pirarubicin and mitomycin-C for the intravesical infusion chemotherapy of NMIBC, a total of 25 RCTs[
68,
71,
76,
82,
89-
109] were included in the meta-analysis, with a total of 2026 patients and a maximum follow-up time of 75 months. Results showed that, in terms of effectiveness, the 1-year recurrence rate (
RR=0.50, 95%CI 0.36–0.68) and 2-year recurrence rate (
RR=0.45, 95%CI 0.36–0.57) of the pirarubicin group were lower than those of the mitomycin-C group, but there was no significant difference in the 3-year recurrence rate between the two groups (
RR=0.66, 95%CI 0.42–1.03). In terms of safety, the incidences of total adverse reactions (
RR=0.55, 95%CI 0.42–0.73), bladder irritation sign (
RR=0.60, 95%CI 0.48–0.76) and hematuria (
RR=0.53, 95%CI 0.30–0.94) in the pirarubicin group were lower than that in the mitomycin-C group. There was no significant difference in the incidence of cystitis between the two groups (
RR=0.94, 95%CI 0.37–2.39). Except for the indicators for total adverse reactions and cystitis, there was no heterogeneity among the included studies in other outcome indicators. Subgroup analysis was carried out according to the dosages and medication schemes. The results showed that when comparing the prognosis of patients under different doses of pirarubicin and mitomycin-C, the 2-year recurrence rates in the pirarubicin group were all lower than that in the mitomycin-C group. In the patients treated with induction and maintenance instillation, or combined induction and maintenance instillation immediately after TURBT, the 1-year and 2-year recurrence rates of the pirarubicin group were lower than those of the mitomycin-C group (Additional file 3: Table S1). (4) To compare the efficacy and safety of intravesical instillation chemotherapy with different doses of epirubicin in the treatment of NMIBC, a total of 8 RCTs (12 studies)[
110-
117] were included in the meta-analysis, with a total of 1114 patients and a maximum follow-up time of 60 months. Results showed that there was no significant difference in the efficacy (1-year and 2-year recurrence rate) and safety (total adverse reaction rate) between the groups of high-dose (>80 mg)
vs. common-dose (50–80 mg), high dose (>80 mg)
vs. low dose (< 50 mg), common dose (50–80 mg)
vs. low dose (<50 mg) of epirubicin in the treatment of NMIBC. (5) To compare the efficacy and safety of intravesical instillation chemotherapy with different doses of pirarubicin in the treatment of NMIBC, 2 RCTs (4 studies)[
118,
119] were included in the meta-analysis, with a total of 258 patients and a maximum follow-up time of 38 months. Results showed that the 2-year recurrence rate under pirarubicin treatment (
RR=0.35, 95%CI 0.18–0.68;
RR=0.44, 95%CI 0.22–0.89) was lower in 50 mg dosage group than that in the 30 mg or 40 mg dosage groups, but the incidence of bladder irritation (
RR=1.91, 95%CI 1.16–3.15;
RR=2.15, 95%CI 1.19–3.89) was higher in 50 mg pirarubicin group. There was no significant difference in the above indexes between the dose groups of pirarubicin at 40 mg and 30 mg. (6) A network meta-analysis published in 2020 evaluated the efficacy of mitomycin-C, doxorubicin, epirubicin, gemcitabine and thiotepa in the treatment of NMIBC, including 55 RCTs and 12,462 patients[
120]. Results showed that compared with TURBT only, except doxorubicin (
HR=0.94, 95%CI 0.66–1.35) and cetidipine (
HR=0.36, 95%CI 0.10–1.26), the other three chemotherapeutic drugs could reduce the risk of disease progression, with a ranking of gemcitabine > mitomycin-C > epirubicin in their superiority of therapy. Except for cetidipine (
HR=0.69, 95%CI 0.41–1.14), the other four chemotherapeutic drugs could reduce the risk of recurrence, with a ranking of gemcitabine > mitomycin-C > epirubicin > doxorubicin in their superiority of therapy. Considering the combined results of recurrence and progression, gemcitabine was the most effective treatment regimen. In the subgroup analysis according to drug regimen, tumor characteristics and literature quality, the results are still stable. (7) We also referred to the EAU guideline[
11], NICE guideline[
17], NCCN guideline[
18], and Guidelines for Diagnosis and Treatment of Urology and Andrology in China [
7] (Additional file 2: Question 10).