This is only my opinion, but if the tumor is near the surface, I would either try zapping with a good zapper or would try Rife therapy. I can not make any guarantees that this would work, but I would try it on myself in preference to most anything.
I have read that cats respond well to milk thistle which helps boost liver function.
The best cancer therapies that I have heard of are Cesium chloride and Oleander soup. I have take the Cesium as a preventative but did not have cancer identified at the time.