[Reappraisal of the clinical usefulness of transabdominal ultrasonography for advanced colon cancer--a study of tumor detection].

We evaluated the detectability of colon cancer by using transabdominal ultrasonography (US). Fifty-three cases of proven advanced colon cancer were examined in this study. Screening by US was carried out in 27 of 53 cases and US was performed in all cases after the definite diagnosis. Lesions of the colon were examined by using a 3.5 MHz convex and 5 MHz or 7.5 MHz linear probe (Yokogawa RT-2800, RT-4600). Localized hypertrophy of the irregular wall of more than 10 mm or massive tumor without the normal layered structure was defined as colon cancer on US. The rate of detection by screening test was 52%. The detection rate by US after definite diagnosis was 75%. A high detection rate was obtained in cases with a tumor diameter of more than 4 cm. Eight of 13 cases which were not detected by the screening test were visualized by US after definite diagnosis. US examination is useful for the detection of certain extended lesions of colon cancer. With technical improvements of the examination method, it is considered that cancer in the gastrointestinal tract may be discovered early on screening tests using US.