Although 'insignificant' prostate cancer has been examined separately in radical prostatectomy (RP) and radical cystoprostatectomy (RCP) studies, it is not entirely clear whether cancers designated as 'insignificant' on RP and RCP represent the same, similar or different forms of prostate cancer. Insignificant prostate cancer has been traditionally defined based on the pathological findings in the whole prostate gland. In addition to the pathological determinants of 'insignificant' prostate cancer, it is also important to account for the biological and the clinical context of the disease, as well as patient age and health status to designate a prostate cancer 'insignificant'. This review examines and compares prostate cancers described as 'insignificant' on RP and RCP. We conclude that in most cases these low-volume/low-grade prostate cancers represent an early stage and clinically 'silent' disease, which are only detected in different clinical settings.