stage 3b malignant melanomamalignant melanoma stage 2bstage 3b melanoma prognosismelanoma stage 2b prognosisstage 3b renal failurestage 3b melanoma survivalstage 3b melanoma cancer3b kidney disease3b melanomastage 3b melanoma life expectancystage 3b melanoma survival ratestage 2b melanoma survival rate