Prevalence and clonality of synchronous primary carcinomas in the bladder and prostate

Incidental prostate adenocarcinoma (IPCa) has been frequently discovered during postoperative histopathological evaluation of radical cystoprostatectomy specimens in patients with bladder cancer (BCa). However, there is currently no conclusive study addressing the clinical significance of IPCa and the clonal relatedness of IPCa and BCa. Here, we performed a retrospective single-center review of 919 BCa cases and an additional meta-analysis including a total of 19 868 individuals who underwent radical cystectomy for bladder cancer. IPCa, mostly clinically insignificant, was detected in 67 of 919 BCa patients (7.3%) and was significantly associated with greater age. In the meta-analysis, a lower prevalence was observed in Asian than in non-Asian countries (19% versus 32%), presumably due to their different rates of prostate cancer occurrence. Whole-exome sequencing on matched BCa and IPCa samples unambiguously revealed independent clonal origins of the synchronous tumors. BCa and IPCa lesions from each patient displayed distinctive genomic abnormalities and largely unrelated mutational signatures of single nucleotide variations, indicating disparate mutational processes underlying bladder and prostate oncogenesis. These findings provide important insights into the incidental nature of prostate adenocarcinoma in patients with bladder cancer, and suggest that the two concurrent diseases can be managed separately. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.