Survival outcomes of pulmonary metastasectomy in advanced melanoma patients: An inverse probability weighted analysis.

Abstract

e21518 Background: Pulmonary metastasectomy (PM) is a commonly performed procedure for certain patients with lung metastasis. We aimed to estimate the effect of PM on the survival outcomes of advanced melanoma patients with lung metastasis. Methods: We queried the Surveillance, Epidemiology, and End Results (SEER) database for all adult patients with advanced melanoma (AYA site recode) with lung metastasis (Stage M1b according to AJCC 7th edition) who were diagnosed from 2010 to 2015. Patients with known liver, brain, or bone metastasis were excluded. Our primary outcomes were overall survival (OS) and cancer-specific survival (CSS) in months. We used Kaplan-Meier plots to compare survival outcomes between treatment groups. We adjusted for potential confounders including age, sex, marital status, primary tumor surgery, chemotherapy, and radiotherapy in a multivariate analysis. We carried out an inverse probability (IP)-weighted Cox regression in an attempt to eliminate the effect of nonrandomization when estimating the treatment effect of PM on OS and CSS. Results: We included 520 patients; 98 (18.8%) underwent PM and 422 (81.2%) did not. The sample median age was 71 (IQR: 61-80). T0 stage was prevalent in 179 (34.4%) and N0-1 in 302 (58.1%). Primary surgical resection was performed for 217 (41.7%) patients, 136 (26.2%) patients had undergone chemotherapy, and radiotherapy was administered in 64 (12.3%) patients. Patients who underwent PM had a higher median OS than patients who did not (43.0 months, 95% CI: 25.0-not reached vs. 13 months, 95% CI: 11-16). The median CSS in PM group patients was not reached (95% CI: 43.0-not reached), while it was 16 months (95% CI: 13-21) in non-PM patients. After multivariate adjustment, older age, being single, and not undergoing primary surgical resection, were all significant independent prognostic factors for worse OS and CSS. In contrast, sex and receipt of chemotherapy and/or radiotherapy did not affect either OS or CSS. PM group patients had a significant survival advantage than non-PM patients, in terms of OS and CSS (HR = 0.50, 95% CI: 0.37-0.67 and HR = 0.45, 95% CI: 0.32-0.63, respectively). On the IP-weighted Cox analysis, the survival benefits of PM were still significantly favorable for OS (IP-weighted HR = 0.42, 95% CI: 0.30-0.59) and CSS (IP-weighted HR = 0.38, 95% CI: 0.26-0.57). Conclusions: PM in a multimodality treatment setting resulted in a marked survival advantage for patients with advanced melanoma who had lung metastasis only. The management of such patients should be delicately individualized to optimize their survival outcomes.