Sarlacc digests its food in thousands years. And, during this period the victim is kept alive.
Is it possible to rescue a victim who has been swallowed by Sarlacc? Has it been happened possibly in EU?
Though no one in recorded history had ever escaped from the Sarlacc, Fett was able to escape, although not entirely unscathed.
Wookiepedia on Bobba Fett: http://starwars.wikia.com/wiki/Boba_Fett