Check out post 23 here for the good update from ValI realize this thread is old, but my Jake was just diagnosed with an anal gland carcinoma two weeks ago. 20mm, so not huge, but not tiny either. We just had our first appointment with the oncologist and she said the tumor was pliable and easily movable, so it hadn't attached to any muscle tissue (a good thing). There were also no signs of any spread, not even to the local lymph nodes. She recommended surgery, which we are having done in the next couple of weeks. We definitely do not want to do any radiation or chemotherapy, but if the biopsy shows that the cells are aggressive, we might consider immunotherapy like Palladia. We're also seeing a holistic vet and plan to put him on whatever diet and supplements she recommends.
Good luck with your journey and keep us posted!