Abstract
The cases judged to require detailed examination in the abdominal ultrasonographic mass screening were classified under categories III to V and were investigated later in detail. About 66,000 examinees examined in 2004 were classified under categories I to V concerning the possibility of cancer. There were 504 category-III cases, 29 category-IV, 24 category-V, and 557 (0.84%) requiring detailed examination (categoriesIII to V). Nine (2%) cancer cases were detected in category III, 9 (31%) in category IV,. and 9 (37%) in category V. The incidence of malignant tumor rose with the ordinal number of the category. It would have been possible to classify the cases in category III which were actually malignant as category V, if we had judged the cases more accurately. There were 4 cases which were classified as category V but were actually benign diseases. Compared with more experienced screeners, the screeners with less experience tended to classify malignant cases under lower categories. The cases in category V which were actually benign were extremely rare.
