Literature retrieval results
Through the retrieval strategy formulated above, a total of 3,015 literature was found. 896 duplicated literature was discarded and other 2,073 literature was removed by browsing titles and abstracts. Thus, 46 literature was selected for full-text paper review and 17 literature was included in this study. Screening process for the literature was shown in Fig. 1.
Basic features of literature and results of quality assessment
This study included 17 literature with 4,106 patients, while the literature consisted of 5 retrospective studies [10,11,12,13,14] and 12 prospective studies [4, 8, 15,16,17,18,19,20,21,22,23,24]. Among them, 2,066 patients received platinum-based dual drug therapy combining CCRT, while 2,040 patients received platinum monotherapy combining CCRT. Except for 5 retrospective studies, the rest were prospective studies. Basic features of the included literature were displayed in Table 1. The quality assessment results were shown in Fig. 2.
Results of meta-analysis
Evaluation of OS and PFS
The results of OS were reported in 17 studies, comprising 5 retrospective studies and 12 prospective studies. Since there was no heterogeneity (I2 = 0.0%, P = 0.504) confirmed through these studies, we used a fixed-effect model for analysis. The results of meta-analysis showed that CCRT with platinum-based dual drug therapy notably improved OS of LACC patients (HR = 0.68, 95% CI 0.58–0.79). The subgroup analysis on prospective studies exhibited that patients received platinum-based dual drug therapy combining CCRT had long OS (HR = 0.66, 95% CI 0.53–0.78), as displayed in Fig. 3.
The results of PFS were reported in 15 studies, containing 5 retrospective studies and 10 prospective studies, showing low heterogeneity (I2 = 28.1%, P = 0.148). The results of meta-analysis showed that CCRT with platinum-based dual drug therapy remarkably prolonged PFS (HR = 0.67, 95% CI 0.58–0.77). The subgroup analysis on prospective studies illustrated that platinum-based dual drug therapy combining CCRT ameliorated patients’ PFS (HR = 0.75, 95% CI 0.60–0.89), as represented in Fig. 4. In conclusion, CCRT with platinum-based dual drug therapy presented more significant efficacy and significantly prolonged the survival of LACC patients, which had a broad application prospect.
Analysis of adverse events
In addition, we performed a pooled analysis of grade 3 and above chemotherapy-related adverse events (Fig. 5). There were prominent differences in adverse events except for vomiting (OR = 1.25, 95% CI 0.95–1.65). Neutropenia (OR = 4.92, 95% CI 3.55–6.84), anemia (OR = 1.99, 95% CI 1.17–3.39), diarrhea (OR = 1.70, 95% CI 1.30–2.22), leukopenia (OR = 2.42, 95% CI 1.84–3.17), thrombocytopenia (OR = 2.87, 95% CI 1.44–5.72), etc. were significantly increased in the CCRT with platinum-based dual drug therapy group. It was obvious that multiple chemotherapeutic drugs would increase the occurrence of adverse events. Thus, the advantages and disadvantages should be weighed to maximize the survival of patients.
It was found that the funnel plot was basically symmetrical by observing visually. Assessed by Egger’s test (OS, P = 0.611; PFS, P = 0973), publication bias was not existed (Fig. 6). The evidence indicated that the included studies had no effect on the results of the meta-analysis.