dr. henderson: premiere zhou en lai had bladder cancer. in the course of his illness, he became interested in cancer and actually was a mover in getting a national register of cancer cases. a million barefoot doctors in every village in china recorded every cause of death.

dr. henderson was asked to find out. dr. henderson: there was a friend of mine working in taiwan at the time who published an elegant study showing that hepatitis b virus looked like a common explanation in taiwan for liver cancer. so we did studies with them, collected blood from about 10,000 people, tested the blood back here in the united states, and followed them and demonstrated that the same virus was causing liver cancer in china. and from that evolved a series of national vaccination programs. it's just such breakthroughs that have intensified data collection efforts around the world. dr. bernstein: we collect information on the type of tumor and all of the characteristics of the cancer, the stage, the cell type, the extent of disease, laterality, anything we can get about that. we also collect information about the individual who is diagnosed with cancer-- their gender, male or female, their race or ethnic background, their age, where they were born, if we can get that information, what their last occupation was. we'

dr. michael a. prepresaro. he said please tell me that she's dead. there's terry hendersonho said that he was a co-worker of john weis. the couple agreed they didn't want to live out their years bed rid on and disabled. he says that john wise suffered from nerve damage and particular bladder cancer. so they weren't in good health. but the fact remains, the law that says, if then in ohio that law doesn't exist. >> that's absolutely correct, shep. that law does not exist. as sympathetic as it is. there's no much sing as a mercy killing defense. that leads me to believe that that's good evidence for the prosecution. because the prosecution is going to rely upon those statements to say that mr. wise knew what he was doing, he didn't want his wife to suffer, and that he took the matter and he took the law into his own hands by shooting her. and of course, that admission to the doctor asking is she dead, that implicates that he perhaps knew what he was doing. so the prosecution is going to use those statements to their advantage whereas the defense is really going to rely upon th