Why do you think AI is inherently worse than humans in judging whether a patient has cancer, assuming they are given the same information as the human doctor? Is there some fundamental assumption that makes AI worse, or are you simply projecting your personal belief (trust) in human doctors? (Note that given the speed of progress of AI and that we're talking about what the law ought to be, not what it was in the past, the past performance of AI on cancer cases do not have much relevance unless a fundamental issue with AI is identified)

Note that whether a person has cancer is generally well-defined, although it may not be obvious at first. If you just let the patient go untreated, you'll know the answer quite definitely in a couple years.