ObjectiveTo systematically evaluate whether primary tumor resection (PTR) has a statistical survival benefit as compared with chemotherapy alone (CTA) for asymptomatic stage Ⅳ colorectal cancer patients with unresectable synchronous metastasis (ACRCUSR). MethodsThe PubMed, Embase, Web of Science, Cochrane Central, CNKI, Wanfang, and the other databases were searched systematically and the prospective or retrospective controlled studies of PTR versus CTA in treatment of ACRCUSR were collected. The outcomes included overall survival (OS) and overall 1–5-year survival rates. The Stata 12.0 and RevMan 5.3 softwares were used for the pooled-analysis of relative risk (RR) and hazard ratio (HR). The trial sequential analysis (TSA) software was used to analyze overall 5-year survival rate and calculate the sample size required to achieve stable results. ResultsA total of 35 studies involving 258 478 patients were included. The results of pooled-analysis showed that the OS of ACRCUSR with PTR was statistically better than that with CTA [HR=0.57, 95%CI (0.52, 0.61), P<0.001]; Meanwhile, it was found that the overall survival rates at 1-, 2-, 3-, 4-, and 5-year of ACRCUSR with PTR were statistically better than those with CTA [1-year: RR=1.30, 95%CI (1.21, 1.40), P<0.001; 2-year: RR=1.78, 95%CI (1.64, 1.93), P<0.001; 3-year: RR=2.10, 95%CI (1.65, 2.68), P<0.001; 4-year: RR=3.05, 95%CI (2.07, 3.44), P<0.001; 5-year: RR=3.43, 95%CI (3.00, 3.92), P<0.001]. The TSA showed the reliable outcome at overall 5-year survival rate and the sample size required to achieve stable result was 96 662 cases. ConclusionFrom analysis results of this study, for ACRCUSR with PTR can benefit survival as compared with CTA, which still needs to be verified by more randomized controlled trials.
ObjectiveTo evaluate effect of RAS gene mutation after liver metastasis resection on overall survival (OS) and disease-free survival (DFS) for patients with colorectal cancer combined with liver metastasis. MethodsA comprehensive and systematic literature search in the PubMed and other databases was conducted, with the final search ending on January 5, 2022. The impact of RAS gene mutation after liver metastasis resection on survival of patients with colorectal cancer combined with liver metastasis was analyzed by the Stata 12.0 software and Review Manager version 5.3 software, meanwhile which were analyzed according to subgroups, including study type (retrospective and prospective studies), region (Asian and European), and number of RAS gene mutation sites (>2 and ≤2). ResultsA total of 26 studies with 13 356 patients were included. The integrated analysis results showed that the patients with RAS mutations had statistically shorter OS [HR=1.54, 95%CI (1.43, 1.65), P<0.001] and DFS [HR=1.32, 95%CI (1.19, 1.44), P<0.001] as compared with RAS wild-type. Except the 1-year overall survival rate, the 2–5-year overall survival rate and 1–5-year disease-free survival rate of patients with RAS gene mutation were statistically lower than those of patients with RAS wild-type (P<0.05). The results of subgroup analysis showed that no matter retrospective and prospective studies, as well as studies in Asian and European countries, it was found that the OS and DFS for patients with RAS gene mutation were shorter than those of patients with wild-type (P<0.05); At the same time, subgroup analysis of the number of RAS gene mutation sites showed that OS and DFS of patients with number of mutation sites >2 were shortened as compared with ≤2 (P<0.05). ConclusionFrom the overall analysis results, the survival of patients with RAS gene mutation after liver metastasis resection is worse than that of patients with RAS wild-type for patients with colorectal cancer combined with liver metastasis.