Radiotherapy combined with locoregional hyperthermia for oligoprogression in metastatic melanoma local control

The evidence base for the management of oligoprogression in metastatic melanoma (MM) is limited. To our knowledge, this study presents the first analysis of the local benefit (LB) of radiotherapy combined with hyperthermia during systemic treatment in this diagnosis.

Patients with oligoprogressive MM who were treated with radiotherapy (RTH) combined with hyperthermia (HT) at a melanoma center between 2019 and 2023 were evaluated. Oligoprogression was defined as up to five progressive metastases. Inclusion criteria was the availability of dimensions assessment of the lesion subjected to RTH before and after treatment, patients without follow-up imaging after radiotherapy were excluded. The benefit of RTH + HT was evaluated in terms of local control (LC) rates and LB rates. LC was defined as the percentage of patients who met the Response Evaluation Criteria In Solid Tumors (RECIST 1.1) criteria for stable disease (SD), partial response (PR), and complete response (CR). LB was defined as the proportion of patients who met the PR and CR criteria. In addition, overall survival (OS) rates were estimated. The association between BRAF status, age, concomitant systemic treatment, radiation total dose, and biologically effective dose and LC was estimated. Data regarding adverse effects associated with RTH + HT were compiled. Survival analyses were performed using the Kaplan-Meier estimator and log-rank tests and were used to compare between groups.

In total, 101 patients were included in the study, the median follow-up was 15.3 months (14-18 months). There were 56.4% BRAF(-) and 43.6% BRAF(+) patients. Most patients (71.3%) were irradiated during immunotherapy, 10.9% received concomitant BRAF and MEK inhibitors, and 3.9% had chemotherapy. LC and LB medians were not reached at the time of analysis. The 1- and 2-year LC rates were 93.5% (95% confidence interval (CI): 88.1%-99.3%) and 88.3% (95% CI: 79.9%-97.6%), respectively. The 1- and 2-year LB rates were 87.5% (95% CI: 80.5%-95.2%) and 78.1% (95% CI: 67.9%-89.9%), respectively. The mean reduction in irradiated tumor size across the entire cohort was 72%. The mOS from radiotherapy was not achieved at the time of our analysis, accordingly 1- and 2-year OS rates were 100% and 95% (95% CI: 90.4%-99.9%). None of the evaluated factors influenced LC among patients.

Hyperthermia with radiotherapy is an effective treatment for patients with oligoprogressive melanoma. This approach has resulted in excellent LC.