dad is in denial

My father keeps running my mother from doctor's apt. to doctor's apt. although she is clearly dying from her lung cancer.  I have tried to convine him that it is futile and cannot possibly be comfortable for her.  She has been bed bound for about three weeks now and consumes less than 100 calories a day.  Any suggestions for how to cope with him and puting her through these useless doctor's visits?  If she were in her right mind, she would be protesting.