Effects of S-1 Combined with Radiotherapy in the Treatment of Nasopharyngeal Cancer: A Meta-analysis Based on Randomized Controlled Trials

The aim of this meta-analysis was to evaluate the effects and toxicity of S-1 combined with radiotherapy in the treatment of nasopharyngeal cancer (NPC). Through a search of the databases of PubMed, Embase, the Chinese Biomedicine Database (CBM), China National Knowledge Infrastructure (CNKI), Wanfang system and Chongqing VIP Information (CQVIP), the efficacy and side effects data of S-1 combined with radiotherapy in the treatment of NPC patients from open published randomized controlled trials (RCTs) were collected. The pooled complete response (CR), partial response (PR), objective response rate (ORR), 2-year survival rate and treatment related toxicity were analyzed by Stata12.0 software. Eight RCTs with 599 cases were included and analyzed in this meta-analysis. The general quality of the 8 studies were deemed as having moderate risk of bias. Adequate sequence generation was reported in 4 studies. Incomplete outcome data address was reported in 7 publications. Five studies indicated to be free of selective reporting. Seven studies reported the treatment complete response (CR) between S-1 combined with radiotherapy and radiotherapy alone. With significant heterogeneity, the data was pooled by random effect model. The pooled results indicated that S-1 combined with radiotherapy can significant increase the CR rate compared to radiotherapy alone (RR=1.52, 95%CI:1.33-1.74, P<0.05). Eight studies reported the partial response (PR) rate between the combined treatment and radiotherapy alone. The pooled results showed that there was no statistical difference for PR between combined treatment and radiotherapy alone (RR=0.85, 95%CI:0.62-1.16, P>0.05). For the effect size of objective response rate (ORR), pooled results indicated that S-1 combined with radiotherapy can significantly increased the ORR by random effect model (RR=1.39, 95%CI:1.23-1.57, P<0.05). The pooled results showed that S-1 combined with radiotherapy significant increase the risk of developing bone marrow suppression (RR=1.94, 95%CI:1.40-2.69, P<0.05) and gastrointestinal reaction (RR=1.81, 95%CI:1.38-2.38, P<0.05) with fixed effect model. However, the pooled oral mucositis (RR=1.22, 95%CI:0.99-1.50, P>0.05) and radiodermatitis (RR=0.93, 95%CI:0.77-1.12, P<0.05) were not statistically different. Two studies reported the 2-year survival rate between the two groups. The pooled results showed the combined treatment significantly increased the 2-year survival rate for patients with nasopharyngeal carcinoma (RR=1.14, 95%CI:1.01-1.28, P<0.05). The funnel plot demonstrated significant publication bias for complete response, partial response, objective response rate and oral mucositis. The egger’s line regression test indicated significant publication bias for complete response (t=5.98, P=0.002) and objective response rate(t=6.23, P=0.003). Conclusion S-1 combined with radiotherapy can significant improve the clinical efficacy with more treatment related toxicity compared to radiotherapy alone in the treatment of nasopharyngeal carcinoma.