When comparing concurrent and non-concurrent application, we found significant differences in the subgroup of patients with cancer types other than melanoma (p = 0.006); when PTV was >3 cm3 (p = 0.007); in the group of patients with low NLR (p = 0.039); with BED <60 Gy (p = 0.014); with dexamethasone intake of ≤4 mg (p = 0.042); and in the subgroup of anti-CTLA4-naïve patients (p < 0.001), also when considering only melanoma patients (p = 0.028). The gene discussed is CTLA4; the disease is melanoma.