Survival Benefit and Prognostic Determinants of Conversion Surgery in Patients With Stage IV Gastric Cancer: A Single-center Study

<h3>Background/Aim:</h3> Conversion surgery (CS) in patients with stage IV gastric cancer (GC) who respond to chemotherapy is a promising strategy, but its prognostic value remains unclear. In this study, clinical outcomes were evaluated, and prognostic factors were identified in patients who underwent CS. <h3>Patients and Methods:</h3> We retrospectively analyzed 443 consecutive patients who were diagnosed with stage IV GC and treated at the University of Toyama Hospital between January 2002 and January 2023. Patients were categorized into the following treatment groups: chemotherapy alone (CA), upfront surgery (US), and CS. Prognostic factors for overall survival (OS) in the CS group were examined using univariate and multivariate analyses. <h3>Results:</h3> Among the 443 patients, 343 underwent CA, 62 underwent US, and 34 underwent CS. The 5-year OS rates and median survival times were 8.1% and 11.7 months (CA), 21.4% and 16.2 months (US), and 37.1% and 33.5 months (CS) for the CA, US and CS groups, respectively, and significant differences were observed among the groups. Distant metastasis was less frequent in the CS group. A univariate analysis revealed a high preoperative lymphocyte count (≥1600/μl) and R0 resection as favorable factors. A multivariate analysis confirmed that a lymphocyte count ≥1600/μl [hazard ratio (HR)=0.37; <i>p</i>&lt;0.05] and R0 resection (HR=0.04; <i>p</i>&lt;0.01) were independent predictors of improved OS. <h3>Conclusion:</h3> CS is effective for select patients with stage IV GC, especially those with R0 resection, preserved lymphocyte counts, and low tumor burden (≤pT4, Yoshida category).