Assuming that you mean musculoskeletal oncology, it is a very small specialty of orthopedics. Most tumor guys are at University settings. Many do not do 100% tumor b/c of lack of volume so many of them also run a joint replacement practice in addition. Most states probably only have a couple of tumor guys (we have only one in Iowa).
At Wisconsin, where I trained, the tumor guy took trauma call just like everyone else.
I'm not sure what the demand is for them. Given how few are trained yearly, it is probably not hard to find a job, but it may not be where you want to live.
Knowing how coding works, reimbursement is probably not that great given the time factor in many of the cases.