IMO, I would think, if it's just Grade 1, that you would not need to see an oncologist.
Shasta had a Grade 2 removed from her side. And I never went to an oncologist.
What I did do was also go to a holistic vet (in addition to my regular vet) to see what I could do from that angle.
I also changed her to a grain free diet and tried to find the lowest carbs within the gf food.
Also worked on her immune system. Gave her essiac tea for 8 months to a year along with supplements & milk thistle.