1. First Department of Internal Medicine (M.I., T.U., K.E), Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8501, Japan
2. Departments of Clinical Studies (M.I., K.A., K.N., M.A., A.H., N.S., M.S., S.F., M.Y., R.M.), Radiation Effects Research Foundation, Nagasaki 850-0013 and Hiroshima 732-0815, Japan
3. Departments of Statistics (E.N.), Radiation Effects Research Foundation, Nagasaki 850-0013 and Hiroshima 732-0815, Japan
4. Departments of Sasebo Chuo Hospital (T.T.), Nagasaki 857-1195, Japan
5. Japan Radioisotope Association (S.N.), Tokyo 113-8941, Japan