Incidentally detected renal cell carcinomas are highly associated with comorbidity and mortality unrelated to renal cell carcinoma.

Objective: The aim of this study was to investigate the underlying reasons for symptomatic (SRCC) and incidental diagnosis of renal cell carcinoma (IRCC), and possible differences in cancer-specific (CSS) and overall survival (OS) with regard to reasons for detection.

Material And Methods: Between 1997 and 2010, 413 patients underwent surgery for renal cell carcinoma (RCC). SRCCs were divided into groups with general and classical symptoms. IRCCs were divided into "true" IRCCs, found owing to investigation of another definitive medical condition, and "unrelated" IRCCs, found owing to investigation for signs and symptoms presumed to be unrelated to RCC. Gender- and age-adjusted estimated overall survival (EOS) rates based on national mortality data were calculated for both the total material and the subgroups.

Results: IRCC tumours were smaller, and of lower stage and grade than SRCCs, which was also reflected in the lower CSS in this group. Most IRCCs were found during investigations related to another definitive condition. There was a significantly higher level of comorbidity in the IRCC group, and the "true" IRCC group had the highest rates. The two IRCC subgroups had similar CSS and tumour characteristics. In the SRCC group, however, those with general symptoms had worse tumour characteristics and lower rates of CSS compared to those with classical symptoms. The true IRCC group had significantly inferior OS compared to the unrelated IRCCs (p = 0,040). Only the unrelated IRCC patients had an OS similar to the EOS; for all other subgroups the OS was inferior to the EOS.

Conclusions: Most IRCCs were found during investigations for other medical conditions, and the OS rate in this group of patients was lower than expected.