Dr Larry or anyone? Tumor Question?

One way is to opt for the pre-surgical bloodwork. You can call and get an estimate for both the surgery and the bloodwork. At my regular vet I believe the bloodwork itself runs around $40. If you will be using a low cost spay/neuter clinic or service, double check that they offer this service. It checks on a high level to make sure the kidneys, liver, etc are operating in a normal range.