[Long-term prognosis of incidental renal cell carcinoma--clinical analysis of renal cell carcinoma detected by our health checkup].

PURPOSE: We retrospectively evaluated the characteristics and long-term prognosis of incidentally detected renal cell carcinoma by health checkup. MATERIALS AND METHODS: From January 1987 to December 2005, 556 patients were treated for renal cell carcinoma in our department. Among them, 56 patients were detected by abdominal ultrasonography in health checkup of our health care center. We reevaluated the pathological stage according to 2002 TNM classification and tumor type of renal cell carcinoma according to 2004 World Health Organization histological classification. Survival analysis was determined by Kaplan-Meier's method and log-rank test. RESULTS: Of the patients, 50 were male and 6 were female. The age of the patients ranged 37 to 68 years old at diagnosis (median 54 years). The tumors were located in the right kidney in 22 patients and in the left kidney in 34. Pathologically T1a tumors were found in 40 patients (71%), T1b in 13 (23%), T2 in 2 (4%) and T3b in 1 patients (2%). One case of T3b had N2 and M1 disease. The followup time after the operation ranged 3 to 215 months (median 121 months). Seven patients died of renal cell carcinoma. One of the 7 patients in T1a disease died at 64 months, 4 in T1b at 47, 91, 119, 163 months, 1 in T2 at 39 months and 1 in T3b at 13 months, postoperatively. The cause specific 10-year survival rate was 97% for T1a disease and 57% for T1b (p < 0.01), respectively. CONCLUSION: Most of renal cell carcinomas were T1a disease, which were detected incidentally by health checkup. The cause specific survival rate was significantly higher for T1a disease than for T1b. Our data suggested that early detection was important for good prognosis. The abdominal ultrasonography was only method for detection in routine health checkup and should be broadly implemented.