I think that it's worse to lose the tumor. If it's small, you can lose the tumor and not lose the leg. If you let it continue to grow, you might not be so lucky a couple of months from now.
Your vet can do pre-anesthesia bloodwork which can help to eliminate some of the risk by pointing out problems before you knock her out.
In my opinion, surgery is the way to go.
Let me know if you still have questions.