Background: Isolated limb infusion (ILI) is a minimally invasive procedure for delivering high-dose chemotherapy to extremities affected by locally advanced or in-transit melanoma. This study compared the outcomes of melanoma patients treated with ILI in the United States of America (USA) and Australia (AUS). Methods: Patients with locally recurrent in-transit melanoma treated with ILI at USA or AUS centers between 1992 and 2018 were identified. Demographic and clinicopathologic characteristics were collected. Primary outcomes of treatment response, in-field progression-free survival (IPFS), distant progression-free survival (DPFS), and overall survival (OS) were evaluated by the Kaplan-Meier method. Multivariable analysis evaluated whether availability of new systemic therapies affected outcomes. Results: More ILIs were performed in AUS (n = 411, 60 %) than in the USA (n = 276, 40 %). In AUS, more ILIs were performed for stage 3B disease than in the USA (62 % vs 46 %; p < 0.001). The reported complete response rates were similar (AUS 30 % vs USA 29 %). Among the stage 3B patients, AUS patients had better IPFS (p = 0.001), whereas DPFS and OS were similar between the two countries. Among the stage 3C patients, the USA patients had better OS (p < 0.001), whereas IPFS and DPFS were similar. Availability of new systemic therapies did not affect IPFS or DPFS in either country. However, the USA patients who received ILI after ipilimumab approval in 2011 had significantly improved OS (hazard ratio, 0.62; p = 0.013). Conclusions: AUS patients were treated at an earlier disease stage than the USA patients with better IPFS for stage 3B disease. The USA patients treated after the availability of new systemic therapies had a better OS.
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