Must you submit to chemo to get painkiller ???

A pipefitter (80 years old) who lives in Los Angeles, California was diagnosed with pleural mesothelioma (cancer on outside of lung) from breathing asbestos fibers--work related. Last December five doctors agreed that there wasn't any treatment(ie.chemotherapy, radiation, surgery) for the disease and death was imminent. Recently his wife called the oncologist for a prescription for painkiller as the disease has progressed. Now oncologist is prescribing chemotherapy (carboplatin and gemstar)and the painkiller Vicadin "to make him feel better!" Can the relatives who are opposed to this because it is useless, and because they want to minimize cancer care damage cite a statute to stop the oncologist's chemotherapy? Is there a statute that would apply?