Early detection of renal cell carcinoma by ultrasonographic screening--based on the results of 13 years screening in Japan.

Abdominal ultrasonographic (US) screening of 219,640 persons has been performed in the past 13 y, and 723 (0.33%) cases of malignant neoplasm were detected. Renal cell carcinoma (RCC) was detected in 192 cases (0.09% of the examinees). In almost all cases of RCC, no symptoms were evident and no abnormalities were detected in the blood chemistry tests or urinalyses. A total of 189 cases (98%) were resected curatively, and 38% of the tumors were less than 25 mm in size (T1). With respect to pTNM classification, 35% were pT1 and 52% were pT2. No metastasis to the lymph nodes or other organs was found in any case. The cumulative survival rate for cases resected was 97% at 5 y, and 95% at 10 y. Regarding US features of RCC, the internal echo pattern of half of T1 tumors showed homogeneous and hyperechoic, and became heterogeneous as they grew. Other notable US findings in cases of RCC were marginal hypoechoic zone (29%), anechoic component in the tumor (23%), and protrusion from the kidney (85%, 71% of the T1 tumors). US screening is useful for detection of RCC in the early stage. However, to detect small tumors, it is very important to know well the US features of RCC. For cost-effectiveness analysis, it is more effective to examine, not only the kidney, but other abdominal organs. It is expected that many other abdominal cancers, such as hepatocellular carcinoma, gallbladder cancer, pancreatic cancer, and so on, could be found in the early stage by broad implementation of US screening.