Efficacy of radiotherapy and radiotherapy with hyperthermia to delay change of systemic therapy in patients with metastatic melanoma.

Background: The use of radiotherapy (RT) and RT with hyperthermia (HT) as a local treatment for oligoprogression in many tumors is becoming increasingly prevalent. However, there is currently limited data regarding RT efficacy in prolonging systemic therapy in melanoma. To address this lack of evidence, we conducted a single-institution study to establish the role of RT and RT + HT in delaying the time to systemic treatment switch in metastatic melanoma (MM). Methods: Patients with MM who received RT or RT + HT for oligoprogressive lesions at the referral center between 2018 and 2023 were identified. Oligoprogression was defined as up to five progressive metastases. Systemic treatment included immunotherapy and BRAF/MEK inhibitors. All patients who received radiotherapy to the brain and lungs were excluded. The primary endpoint was time to the next systemic therapy (TTNST) after RT/RT + HT. The secondary endpoints included overall survival (OS) and progression-free survival (PFS). Factors influencing TTNST were analyzed. Results: 156 patients were included, 82 patients had RT + HT while 74 had RT only. The median follow-up was 23 months (15.2-34). Immunotherapy was used in 82.7 % and BRAF/MEK inhibitors in 17.3 % of patients. The median TTNST for the overall cohort was 26 months (95 % CI: 14.5- NA), the mTTNST for patients treated with RT + HT was 14 months (95 % CI: 11.4-NA), and for patients treated with RT as sole treatment, it was 28 months (95 % CI: 18.3-NA) (p = 0.6). The median PFS from local treatment was 8 months (95 % CI: 5.1-16) for patients who received RT and 10 months (95 % CI: 5.6-12.6) for patients who received RT + HT (p = 0.9). The median OS from RT was 50 months (95 % CI: 40- NA) for patients who received RT and was not reached for patients who received RT + HT (p = 0.031). None of the analyzed factors influenced median TTNST. Conclusion: Both RT and RT + HT have been demonstrated to extend the duration of systemic treatment in patients with metastatic melanoma. The combination of RT + HT is suggested to be more efficacious than RT alone in the therapy of oligoprogressive disease during systemic treatment of patients, especially for OS.