Changes in the natural history of renal cancer: comparison of Estonian data from the periods 1986-1988 and 1996-1998.

To explain considerable increase in survival of renal cancer patients in Estonia during last decades, we compared the stage distribution, diagnostic and treatment methods for the patient groups diagnosed in the periods 1986-1988 and 1996-1998. A significant difference in stage distribution was detected with an increase for stages I-II and a decrease for stages III-IV in 1996-1998. There was a shift in primary diagnostic methods from intravenous urography and angiography to ultrasonography and computed tomography. In multivariate analysis the independent prognostic factors for overall survival were age, stage, and operation status. In conclusion, the increase in the survival of renal cancer patients has been due to the larger number of cases with the earlier stage, which is associated with the application of ultrasonography and computed tomography. Another factor for better survival was the higher operation rate among patients with stage IV disease, a possible factor was the change in operation techniques.