Adjuvant Radiation Therapy in Macroscopic Regional Nodal Melanoma

Adjuvant radiation therapy (ART) for macroscopic regional nodal cutaneous melanoma has evolved. A significant step was the discovery of targeted therapies, particularly towards V600E-mutated melanoma, and immunotherapy under its different kinds. Prior to this, the defining trial was the Australia and New Zealand Melanoma Trials Group (ANZMTG) 01.02/Trans-Tasman Radiation Oncology Group (TROG) 02.01 phase III trial that showed that ART using three-dimensional conformal radiotherapy (3DCRT) decreased in-field recurrence by 50% (48 Gray (Gy) in 20 fractions). After the advent of systemic therapies, a trial of the combination targeted therapy of dabrafenib plus trametinib toward BRAF V600-mutant nodal cutaneous melanoma showed that all 35 patients achieved a pathological response. Radiotherapy (RT) was found to be safe to give with concurrent combination therapy. A retrospective immunotherapy study found that in 71 patients that received ART after a first recurrence, further in-field recurrence significantly decreased (p = 0.01). For those tumours that do recur in-field, there are now competing therapies like Talimogene laherparepvec or T-VEC. Generally, ART is now used at the first recurrence. The challenge now is to find which melanomas are truly radiosensitive if ART is to have any future role in this scenario.