A POPULATION-BASED ANALYSIS OF SURVIVAL AND INCIDENTAL DIAGNOSING OF RENAL-CELL CARCINOMA PATIENTS IN ICELAND, 1971-1990

The significance of incidental diagnosing in relation to survival of r enal cell carcinoma (RCC) patients is not known. A retrospective, popu lation-based study was carried out in order to evaluate the survival o f RCC patients, with emphasis on incidental diagnosing. Included in th e study were all patients diagnosed with RCC in Iceland between 1971 a nd 1990. The tumours were classified and the extent of the disease sta ged by Robson's method. Crude probability of survival was evaluated fo r every stage, and multivariate analysis applied in order to determine prognostic factors. Out of 408 patients, 15% were diagnosed incidenta lly between 1971 and 1980 and 20% between 1981 and 1990 (p > 0.1), mos t often by intravenous urography. Only 5 tumours were detected inciden tally by ultrasound techniques and 4 by CT scans. Crude five-year surv ival was 76% for stage I disease and 11% for stage IV disease. After c orrection for staging by multivariate analysis, incidental diagnosis a nd the year of diagnosis were not independent significant prognostic f actors for mortality. As in many other studies, our data indicate that incidentally diagnosed RCCs are at a lower stage at the time of diagn osis. On the other hand, the results of our population-based study sho w that ultrasound and CT scanning have not significantly increased the number of incidentally diagnosed rumours. It is therefore not very su rprising that surviving of RCC patients in Iceland has remained the sa me for the last two decades.