As each vet has his or her own professional opinion on how to treat a hamster case, it is best you do not impose my advices onto your vet as he or she may be most unhappy.

From my knowledge with the younger vets trained overseas, usually in Australia, I note that the vets have been trained to take a biopsy of the tumour first, send to the laboratory to check whether it is cancerous or not. Then they will advise further. Unfortunately, the lab results may take over 7-14 days. But it can take one day, depending on the laboratory. The owner may also procrastinate. Soon, the tumour, if malignant, grows fast and becomes inoperable in a small creature, like the dwarf hamster's subcutaneous tumour, as that was probably present in your hamster.

My approach is to take out the tumour early, send to the laboratory for histopathology after surgical removal. As each vet has his or her own idea on what to do, the fate of a pet depends on the action of the vet consulted and on the pro-activeness and knowledge of the owner.

I am presently in Hong Kong and may not reply to you. My advice is still to be pro-active to seek a vet who is comfortable with hamster anaesthesia and surgery. Best wishes.