Identification of pathologically insignificant prostate cancer is not accurate in unscreened men.

Background: Identification of men harbouring insignificant prostate cancer (PC) is important in selecting patients for active surveillance. Tools have been developed in PSA-screened populations to identify such men based on clinical and biopsy parameters.
Methods: Prospectively collected case series of 848 patients was treated with radical prostatectomy between July 2007 and October 2011 at an English tertiary care centre. Tumour volume was assessed by pathological examination. For each tool, receiver operator characteristics were calculated for predicting insignificant disease by three different criteria and the area under each curve compared. Comparison of accuracy in screened and unscreened populations was performed.
Results: Of 848 patients, 415 had Gleason 3+3 disease on biopsy. Of these, 32.0% had extra-prostatic extension and 50.2% were upgraded. One had positive lymph nodes. Two hundred and six (24% of cohort) were D'Amico low risk. Of these, 143 had more than two biopsy cores involved. None of the tools evaluated has adequate discriminative power in predicting insignificant tumour burden. Accuracy is low in PSA-screened and -unscreened populations.
Conclusions: In our unscreened population, tools designed to identify insignificant PC are inaccurate. Detection of a wider size range of prostate tumours in the unscreened may contribute to relative inaccuracy.