Asymptomatic Primary Tumor Resection in Metastatic Colorectal Cancer: A Systematic Review and Meta-Analysis

BACKGROUND: In patients with metastatic colorectal cancer (mCRC) with an asymptomatic primary tumor, there is no consensus on the indication for resection of the primary tumor. METHODS: The PubMed, Embase and the Cochrane Library databases were searched from inception to November 30,2021. A meta-analysis was performed using RevMan (version 5.3.3; The Cochrane Collaboration) on the outcome of mCRC patients with or without resection of the primary tumor in 8 selected studies. RESULTS: This meta-analysis included 2805 colorectal cancer patients with an asymptomatic primary tumor from 8 selected studies. Primary tumor resection (PTR) patients had longer overall survival (OS: MD =6.76 [3.39, 10.12], I(2) = 77%, P < 0.0001), compared with non-primary tumor resection (NPTR) patients. In the subgroup, the randomized controlled trials (RCT) PTR group didn’t have longer overall survival (OS: MD =3.79 [-3.49, 11.08], I(2) = 69%, P= 0.31); the Non-RCT PTR group had longer overall survival (OS: MD =8.42 [3.14, 13.70], I(2) = 89%, P= 0.002). In the meanwhile, compared with NPTR group, the 2-year overall survival rate, the 3-year overall survival rate, 5-year overall survival rate in the PTR group is higher (OR=2.35 [1.74, 3.18], I(2) = 0%, P < 0.00001; OR=3.61 [2.35, 5.54], I(2) = 0%, P < 0.00001; OR=3.02 [1.72, 5.33], I(2) = 48%, P= 0.0001, respectively). CONCLUSIONS: Our results from studies demonstrate that the resection of primary tumor is a prognostic factor for survival in mCRC patients. However, 2 RCTs showed the resection of primary tumor was not related with a significant survival benefit in subgroup. Therefore, a larger RCT in the era of modern chemotherapy and liver resection techniques would be helpful.