The prevalence of renal cell carcinoma diagnosed at autopsy.
To compare the rate of renal cell carcinoma (RCC) detected only at autopsy, from two periods, to determine if the apparent recent increase in RCC in the USA is a true increase or mainly a result of improved imaging techniques, as a true increase in the clinical incidence of RCC should not affect the number of previously undiscovered RCC found only at autopsy. We identified all individuals who underwent autopsy in two periods, 1955-60 (3307) and 1991-2001 (2938), and who were identified with renal tumour either before or after death. Information was obtained on age, sex, histological type and size of tumour, and whether the tumour was identified before or only after death. All cases of RCC detected at autopsy were reviewed for this analysis by one pathologist (L.D.). Between 1955-60 and 1991-2001 there was a 55% reduction in the mean annual number of autopsies. The proportion of malignant renal masses (RCC) did not change significantly (35.4% to 32.8%). The rate of previously unsuspected RCC detected only at autopsy did not change significantly (0.91 vs 0.72 per 100 autopsies). The number of renal masses, both benign and malignant, discovered only at autopsy is declining, possibly because of better detection before death. However, the rate of occult kidney cancer per 100 autopsies did not change significantly between the two periods, suggesting a true increase in the frequency of clinically detected kidney cancer.