IL2 and metastatic melanoma: The discrepancy in the effect of cytokines in metastatic melanoma therapies might be best explained by the following uncontrolled variables: (A) patient selection and clinical/biological risk; (B) variations in the rIL-2 based regimen (e.g., reconstitution of drug, route and dose of administration); and (C) different standards of patient care (e.g., supportive care upon IL-2 therapy).