@hawkeye10,
Yes, I don't generally think insurers should have a direct stake in the outcomes of medical treatment--that goes beyond the limits of their concern, as a business, and they realistically have little control over the outcome of medical treatment for a particular patient. What difference should it make to the insurer if some patients survive cancer with a particular treatment, but others do not? Their obligation is to simply pay for the treatment if it's part of their contractual obligation to the patient.
Insurers can reasonably require that a particular test or treatment be justified, by the health care provider, in terms of the patient's condition or diagnosis, to help curb unnecessary procedures, or duplicate procedures, and the government insurers, like Medicare, do have limits that help to contain costs.
I don't want my insurance carriers going beyond their contractual obligation to me. I don't want them interfering with my medical decisions, or my choices, and I don't want them invading my privacy more than is absolutely necessary.