Multivariate analysis according Cox’s regression, including PS, gender, smoking, skin toxicity of any grade and use of IL-2, revealed that only skin toxicity (p < 0.001; HR 0.29; CI 95% 0.16–0.54) and use of IL-2 (p < 0.001; HR 0.33; CI 95% 0.18–0.60) were significantly associated with improvement in OS independently of other factors. This evidence concerns the gene IL2 and dermatological toxicity.