Clinical effect of surgery combined with adjuvant therapy and single surgery for resectable pancreatic cancer: a Meta analysis

Objective To systematically evaluate the clinical effect of surgery combined with adjuvant therapy (postoperative chemoradiotherapy or chemotherapy) and single surgery for resectable pancreatic cancers. Methods Literatures were researched using PubMed, Embase, Science Citation Index Expanded, Cochrane Central Register of Controlled Trials and China Biology Medicine disc with the key words including "pancreatic cancer, adjuvant therapy, chemoradiotherapy, radiochemotherapy, chemotherapy, radiotherapy,胰腺癌,辅助治疗,化学治疗and放射治疗" from the time of database building to October 2016. Two reviewers independently screened literatures, extracted data and assessed the risk of bias. All the patients undergoing surgery combined with adjuvant chemoradiotherapy, surgery combined with adjuvant chemotherapy and single surgery were respectively allocated into the first treatment group, second treatment group and control group. The inverse variance was used for mergering hazard ratio (HR) and related statistic data. HR and 95% confidence interval (CI) were used for assessing the overall survival time and disease-free survival time. The median survival time and 1-, 2-, 5-year survival rates were evaluated by the relative risk (RR) and 95%CI. The heterogeneity of the studies was analyzed using the I2 test. Results Eleven randomized controlled trials (RCTs) of 9 literatures were retrieved, and the total sample size was 1 482 patients, including 238 patients in the first treatment group, 545 in the second treatment group and 699 in the control group. Results of Meta analysis: ① overall survival time: there was no significant difference in overall survival time between the first treatment group and control group (HR=0.87, 95%CI: 0.56-1.17, P>0.05). There was a significant difference in overall survival time between the second treatment group and control group (HR=0.68, 95%CI: 0.55-0.80, P 0.05). There was a significant difference in disease-free survival time between the second treatment group and control group (HR=0.56, 95%CI: 0.45-0.67, P 0.05). One-year survival rate in the second treatment group was compared with that in the control group, with no significant difference (RR=1.15, 95%CI: 0.99-1.34, P>0.05). There were significant differences in 2- and 5-year survival rates between the second treatment group and control group (RR=1.24, 1.73, 95%CI: 1.01-1.50, 1.32-2.27, P<0.05). Conclusions Compared with single surgery, surgery combined with postoperative chemoradiotherapy cannot significantly improve the overall survival time and disease-free survival time of patients. However, surgery combined with adjuvant chemotherapy can prolong the overall survival time and disease-free survival time of patients. Key words: Pancreatic neoplasms; Adjuvant therapy; Chemotherapy; Radiotherapy; Meta-analysis