internal melanoma stage 4melanoma stage 3 survivalstage 4 melanoma survivorsmetastatic melanoma stagesmetastatic melanoma meaningnodular melanoma stage 4end stage melanomametastatic melanoma stage 4 prognosisprognosis for stage 4 melanoma cancerstage 4 melanoma in lungsstage 4 metastatic melanoma cancerlife expectancy stage 4 melanoma