Kidney cancer in Sweden: A decrease in incidence and tumour stage, 1979-2001

Objective. In the Western world the incidence of renal cell carcinoma (RCC) has been increasing for several decades. In Sweden the incidence has decreased since 1980. This may reflect better health of the population. Another possible explanation could be a decrease in incidentally diagnosed RCC. Since these tumours are smaller, relatively more advanced tumours would then enter the cancer registry. The aim of this study was to compare methods of detection of RCC, tumour characteristics and survival from three periods over a timespan of more than 20 years. Material and methods. Adult patients (n = 515) with RCC were identified in a well-defined population-based area with the same incidence of RCC as the rest of Sweden. Patient data from three periods, 1979 - 1981 (A), 1989 - 1991 (B) and 1999 - 2001 (C), were collected for gender, age, tumour side, method of detection, tumour size, tumour type, metastasis, T stage and Fuhrman grade at the time of diagnosis. Using the Swedish Cause-of-Death Register, cause-specific survival was calculated. When available, tissue was reanalysed according to modern standards by an experienced pathologist. Results. The frequency of ultrasound and computed tomography increased and autopsy and intravenous pyelography decreased with time as the first detection method. There was a significant change towards smaller tumours and less severe stages and grades in more recent periods. Metastatic disease was most common in the first period. The distribution between the different histological tumour types did not change over time. Five-year cause-specific survival increased significantly from 41% to 63%. Subgroup analysis found significantly increased survival for patients with no metastases or with low-grade tumours. Conclusion. The data support a true decrease in the incidence of RCC over time in Sweden with a migration towards lower tumour stages but no change in distribution between the different histological subtypes over time.