Surgery of primary tumor improves the survival of newly diagnosed metastatic melanoma: a population-based, propensity-matched study

BACKGROUND: For the melanoma patients who are with the primary tumor and metastatic disease concurrently (the newly diagnosed metastatic patients), the effect of primary tumor surgery on survival has never been discussed. OBJECTIVE: We sought to estimate this effect based on data from the Surveillance, Epidemiology, and End Results database. PATIENTS AND METHODS: We identified patients with newly diagnosed metastatic melanoma from 2004 to 2015. The effect of primary tumor surgery was assessed by using Cox proportional hazard regression modeling and propensity score matching. RESULTS: Eight thousand three hundred and forty-one patients who had been diagnosed with primary melanoma and metastatic disease at the same time were included in this analysis, of whom 2,554 (30.6%) received primary tumor surgery. In multivariable analysis of the unmatched cohort, primary tumor surgery was an independent protective factor of overall survival (HR =0.617, 95% CI 0.565–0.674; P<0.001) and melanoma-specific survival (HR =0.599, 95% CI 0.537–0.668; P<0.001). In the matched cohort, primary tumor surgery was still associated with better overall survival (13 vs 6 months, P<0.001) and melanoma-specific survival (18 vs 6 months, P<0.001). CONCLUSION: Our results reveal the benefit of primary tumor surgery on the survival of patients with newly diagnosed metastatic melanoma and may fill in the gaps of guidelines for this population. IRB: IRB approval is not required because the SEER data are freely accessible.