Outcomes of Conversion Surgery vs Conventional Systemic Therapy in Stage IV Gastric Cancer: A Systematic Review and Meta-Analysis.

[PURPOSE] The overall prognosis of stage IV gastric cancer (GC) is poor. Large-scale and high-quality evidence on the role of conversion surgery (CS) is limited. This study aims to compare the long-term survival and morbidity in stage IV GC between systemic treatment followed by CS vs systemic treatment only (i.e. no CS).

[METHODS] A systematic search was performed on PubMed, Embase, Scopus, and Cochrane Library till September 2024. The inclusion criteria were patients with stage IV GC who received systemic chemotherapy + / - immunotherapy/other adjunct therapies. Pooled hazard ratio was calculated to compare survival between CS and no CS, and various subgroup analyses were performed.

[RESULTS] There were 36 studies with 3177 patients (CS n = 1273, no CS = 1904) included, consisting of 29 retrospective cohort studies, 6 prospective non-randomized trials, and 1 retrospective case series. The most commonly used chemotherapy regimen (n = 10 studies) was S-1 + cisplatin. The median OS range was 14.4-60.0 months and 4.7-19.9 months in the CS and no CS groups, respectively. Pooled OS (n = 2826 patients, HR 0.36, 95% CI: 0.32-0.40) and PFS (n = 609 patients, HR 0.38, 95% CI: 0.31-0.46) were superior in CS compared to no CS. Overall incidence of anastomotic leak, intra-abdominal abscess, and post-operative bleeding following CS were 5.4%, 3.6%, and 2.0%, respectively.

[CONCLUSION] Survival in patients with stage IV GC is superior with CS following systemic treatment compared to systemic treatment alone, but however, quality of evidence is low considering the predominant inclusion of retrospective studies and heterogeneous selection criteria for CS which may favour those with good tumour biology.