Could my cat have a tumor?

umm.. yea... we had a cat that suddenly got really fat and it had bladder stones and had to be operated on :D he was fine :D! til it came back... and there was nothing the vets could do and he died D'8 she could just be bloated or maybe swollen due to a broken rob or something like that? if it was cancer it would be in a concentrated area in a small lump :) might have gas :O ...