I have a cat that recently had anal glands which needed expressing. After the third time, anitbiotics and a topical treatment she seemed to be getting better - finally. Then we noticed leakage onto her hind legs - she's a longhair mix-breed - and hyper-inflammation around her rectal sphincter to the point that she looks to be 'closed off' but she doesn't like to let one look for too long either.
Today taking her to the vet he diagnosed cancer with no blood work or other tests. We are taking her for a second opinion before deciding to end her life prmaturely. Although she's around 17 years old, we want to be sure. Could the diagnosis of cancer be made simply by visual exam? I simply don't want her to suffer overly if this could cause her bowls to back up, which he said could happen. Any advice or information will be greatly appreciated.

Optional Information:
Age: >12; Female; Breed: Cat - Mixed longhair, Torti

Already Tried:
Vet remedies spelled out in question./p>