Spiritual beliefs and refusing conventional cancer treatments

I have a patient with recurrent, metastatic cancer. He does not believe he has cancer, however. He believes he is cured by his strong faith and many prayers. This certainly makes conversations about chemotherapy challenging. And yet, we all agree he has a right to these beliefs. The majority of the time a patient is allowed to refuse chemotherapy — as long as he has capacity to make his own health care decisions, and I answer his questions and am allowed to explain to him in a way we both understand about the illness and the benefits of the treatments available. Most of us feel OK with the "do both" approach — use prayer but also do all the conventional treatments. And still, I am left to wonder, when he refuses chemotherapy because he doesn't believe he has cancer, how hard do I push? When do I know he understands everything I am trying to express? Why do I feel so uncomfortable with not treating someone due to their spiritual beliefs?

For those of you who treat kids with cancer, things get a lot more complicated. One recent case of a young girl in central Wisconsin who died of undiagnosed type 1 diabetes while her parents prayed her bedside has brought up very strong emotions on both sides. You may also remember the case of the young Canadian man who refused chemotherapy for his recurrent leukemia or the (also Canadian) 3-year-old whose parents refused chemotherapy for his brain tumors in lieu of "optimal nutrition." Tough cases, with good-intentioned people all around. My gut tells me the children should be treated, despite the parents' objections, if there is a reasonable chance of benefit ... but I'm open to your opinions.