life expectancy with stage 4 melanomametastatic lung cancer life expectancytreatment of metastatic melanomamesothelioma life expectancymetastatic melanoma survivalprognosis metastatic melanomaenzalutamide life expectancymedication for metastatic melanomapleural cancer life expectancymesothelioma prognosis life expectancyrenal cancer life expectancymalignant melanoma metastatic