Before my grandmother died of cancer (non-Hodgkins' lymphoma) in 1978, the hospital that was treating her tried some experiemental techniques based on those very ideas. #1 They took blood samples from all adult members of the family, #2 they tried introducing some of my grandfather's antibodies into her system. This didn't "work", but perhaps with earler detection and the general fine tuning that is available these days, a similar approach might. Funny thing, it was only a few years after my grandmother died from cancer (though it may really have been the chemotherapy/radiation that killed her) that my grandparents' _dog_ died from cancer as well!
(My grandfather has always been quite robust health-wise and is still with us today).