Whenever a medical dispute occurs, we often concern if the doctor should be responsible for the patient's death or not. However, it is difficult to judge whether the death is caused by the doctor's treatment or by the disease itself. In this article, we'll discuss two criminal examples of medical dispute, which victims both contract cancer. After explaining the causal relation in the criminal law, I'd like to advance my viewpoint of the relationship between disease, treatment and death, and then comment about the two cases.