I have had experience with this kind of situation but a little different. My MIL kept having odd symptoms that she had NEVER experienced in her life and the family doc kept telling her she was just aging and to not worry. My FIL finally had it and asked his cardiologist if he could recommend a good internist to examine her. The cardiologist said for my FIL to call his office the next business day and make her an appointment, he had been a very very good internist before going for his specialty.
He got a quick appointment and the very first thing they found during an ultra sound was that her liver was covered with small cell cancer, the fasted mover and most lethal. Had the family doc not discounted her symptoms she might have done some tests and found the cancer sooner.
I think that specialists are there for a reason. They study a particular area zealously and are experts on it. Therefore they are the best place to be when there is a problem with it. So call her cancer doc and visit with them.
My point is:
A family doc is not an expert on cancer or cancer treatment and has no business treating anything beyond the basic cold or flu symptom.