Does adjuvant chemotherapy improve the prognosis of patients after resection of pulmonary metastasis from colorectal cancer? A systematic review and meta-analysis

Background It remains controversial whether patients benefit from adjuvant chemotherapy (ACT) after resection of pulmonary metastasis (PM) from colorectal cancer (CRC). This meta-analysis was intended to evaluate the efficacy of ACT in patients after resection of PM from CRC. Methods We systematically retrieved articles from PMC, PubMed, Cochrane Library, and Embase (up to March 5, 2019). Survival data, including overall survival (OS) and disease-free survival (DFS), were tested by hazard ratios (HRs) and 95% confidence intervals (CIs). Results We included 18 cohort studies with a total of 3885 patients. The meta-analysis showed that ACT had no significant effect on OS (HR = 0.78; 95% CI = 0.60–1.03; P = 0.077) and DFS (HR = 0.91; 95% CI = 0.74–1.11; P = 0.339) in patients after resection of PM from CRC. There was no significant difference in OS (HR = 0.79; 95% CI = 0.42–1.50; P = 0.474) in patients after resection of PM from CRC treated with bevacizumab (BV). Subgroup analysis showed that ACT did not improve OS (HR = 0.86; 95% CI = 0.57–1.29; P = 0.461) in patients who had undergone previous resection of extra PM. ACT did not improve OS in patients who had positive hilar/mediastinal lymph node metastasis (HR = 0.80; 95% CI = 0.57–1.14; P = 0.22). Conclusion In conclusion, ACT does not provide survival benefits for patients after resection of PM from CRC. ACT and targeted agents (BV) are not suggested for these patients.