Amazing Spider-Man #431 (1998)

 The Carnage Cosmic

Silver Surfer, possessed by the Carnage symbiote, takes to space to fight the symbiote without harming innocents, leaving Spider-Man to assist the helpless, cancer-stricken Cletus Kasady. It's discovered the symbiote was keeping his stomach cancer at bay; When Spidey sees the symbiote-possessed Surfer heading towards the hospital to restore the symbiote to Kasady, he tries to stop him until Surfer convinces him otherwise; Carnage is restored, but the Surfer encases him in an ethereal energy shell so he can't harm anyone.  Script by Tom DeFalco, pencils by Joe Bennett, inks by Bud LaRosa. 

Key book;  firt cover appearance & second appearance Carnage Cosmic. Near mint condition.