BackgroundPancreatic cancer is a highly malignant tumor with a poor prognosis. Chemotherapy such as gemcitabine is still an important treatment. Gemcitabine (Gem) may prolong survival time and delay the development of recurrent disease after complete resection of pancreatic cancer. Currently, some control studies have been performed between certain drugs and gemcitabine monotherapy after pancreatic cancer surgery, but the outcomes were uncertain. Here, we implemented meta-analysis to compare the efficacy between adjuvant treatments and gemcitabine monotherapy in patients with resected pancreatic cancer.MethodsPubMed, Embase and the Central Registry of Controlled Trials of the Cochrane Library searches were undertaken to identify randomized controlled trials (RCTs). Date of search ranged from January 1997 to December 2017. The meta-analysis included six RCTs. The major endpoints involved overall survival (OS), disease-free survival/progress free survival/relapse-free survival (DFS/PFS/RFS) and grade 3-4 toxicity.ResultsPooled meta-analytic estimates were derived using random-effects model. Subgroup analysis used fixed-effects model. The outcome showed that there was no difference in OS (hazard ratio (HR), 0.87; 95% CI, 0.70-1.07; P=0.19) and DFS (HR, 0.85; 95% CI, 0.71-1.02; P=0.08) between the adjuvant treatments group (fluorouracil+folinic acid, S-1, gemcitabine+capecitabine, gemcitabine+erlotinib and gemcitabine+uracil/tegafur) and Gem monotherapy group. However, the subgroup analysis showed that only S-1 chemotherapy, which is an oral fluoropyrimidine agent containing tegafur, gimeracil and oteracil, was significant in OS (HR, 0.59; 95% CI, 0.46-0.74; P<0.0001) and DFS (HR, 0.63; 95% CI, 0.52-0.75; P<0.00001) compared with Gem alone. Toxicity analysis showed there was an increased incidence of grade 3/4 diarrhea (risk ratio (RR), 5.11; 95%CI, 3.24-8.05; P<0.00001) and decreased incidence of grade 3/4 leucopenia (RR, 0.55; 95%CI, 0.31-0.98; P=0.04), thrombocytopenia (RR, 0.61; 95%CI, 0.39-0.97; P=0.04) in adjuvant treatments group. Neutropenia (RR, 0.69; 95%CI, 0.36-1.29; P=0.24) and fatigue (RR, 1.29; 95%CI, 0.95-1.77; P=0.11) for patients between the two groups were not significantly different.ConclusionsIn our meta-analysis, a significant survival benefit is only observed in the S-1 regimen, but the results are yet to be determined. Optimal cytotoxicity or targeted drug regimens need further validation in clinical trials in the future.