Adenoid cystic carcinoma and mucosal melanoma are two radioresistant tumors and lying closely proximal to critical structures. This review article examined clinical data available today for particle therapy including proton, carbon ion and neutron for these two conditions. Particle therapy appears to improve disease control – proton therapy and carbon-ion therapy provide excellent 5-year LC rates, ranging from 73% to 90% for ACC and 62% to 84% for MM.

There is yet direct comparison to photon data. Consideration for a phase III trial is complicated by disease rarity and consideration of clinical equipoise versus conventional treatment; in the absence of a prospective and randomized approach, propensity-standardized comparative exploration is warranted.