The Association of Radiation Dose-Fractionation and Immunotherapy Use With Overall Survival in Metastatic Melanoma Patients

• Published in: Curēus (Palo Alto, CA) Vol. 12; no. 6; p. e8767
• Main Authors: Wang, Shang-Jui, Jhawar, Sachin R, Rivera-Nunez, Zorimar, Silk, Ann W, Byun, John, Miller, Eric, Blakaj, Dukagjin, Parikh, Rahul R, Weiner, Joseph, Goyal, Sharad
• Format: Journal Article
• Language: English
• Published: Palo Alto Cureus Inc 22.06.2020; Cureus
• Subjects: Age; Cancer therapies; Chemotherapy; Clinical trials; Comorbidity; Fractionation; Immunotherapy; Melanoma; Metastasis; Oncology; Patients; Radiation Oncology; Radiation therapy; Variables
• ISSN: 2168-8184; 2168-8184
• DOI: 10.7759/cureus.8767

ObjectiveMetastatic melanoma patients often receive palliative radiotherapy (RT) and immunotherapy (IT). However, the immunological interplay between RT dose-fractionation and IT is uncertain, and the optimal treatment strategy using RT and IT in metastatic melanoma remains unclear. Our main objective was to examine the effect of RT dose-fractionation on overall survival (OS).MethodsUsing the National Cancer Database (NCDB), we classified metastatic melanoma patients who received palliative RT into two dose-fractionation groups - conventionally fractionated RT (CFRT; <5 Gy/fraction) and hypofractionated RT (HFRT: ≥5 Gy/fraction) - with or without IT. Survival analysis was performed using the Cox regression model, Kaplan-Meier method, and propensity-score matching (PSM).ResultsA total of 5,281 metastatic melanoma patients were included, with a median follow-up of 5.9 months. The three-year OS was highest in patients who received HFRT+IT [37.3% (95% CI: 31.1-43.5)] compared to those who received HFRT alone [19.0% (95% CI: 16.2-21.9)], CFRT+IT [17.6 (95%CI: 13.9-21.6)], or CFRT alone [8.6% (95%CI: 7.6-9.7); p<0.0001]. The magnitude of OS benefit with the use of IT was greater in those who received HFRT (18.3%) compared with those who received CFRT (9.0%) (p<0.0001). The addition of IT to HFRT, compared to CFRT, was associated with greater OS benefit in patients treated with RT to the brain and soft tissue/visceral (STV) sites. On PSM analysis, HFRT+IT was associated with improved three-year OS compared to other treatments.ConclusionMetastatic melanoma patients who received HFRT+IT was associated with the greatest OS benefit. Our findings warrant further prospective evaluation as to whether higher RT dose-per-fraction improves clinical outcomes in metastatic melanoma patients receiving IT.