Pathological characterization of unifocal prostate cancers in whole-mount radical prostatectomy specimens

• To characterize the anatomical distribution and pathological features of unifocal cancers, which have been reported to occur in 17-33% of men undergoing radical prostatectomy (RP), in whole- mount prostatectomy specimens.

• Between 1999 and 2008, a retrospective review of 1274 patients undergoing RP for clinically localized prostate cancer with pathological evaluation using whole-mount sectioning techniques and tumour mapping was performed from our prospective database. • The study cohort comprised those patients who were found to have unifocal tumours.

• A total of 176 (14%) patients fulfilled our criteria for having unifocal tumours. The median age at time of surgery was 61 years. The mean preoperative PSA level was 8.6 ng/mL. • In all, 28% of patients were identified as having extracapsular extension (ECE) and 11% had seminal vesicle invasion (SVI). • Of 98 patients undergoing pelvic lymph dissection, six (6%) had positive lymph nodes; 49% of tumours had Gleason score ≥7 and 60% had Gleason pattern 4 or 5 found within the tumour. • Mean tumour volume and maximum diameter were 3.3 mL and 1.7 cm, respectively. Overall, 89 (51%) tumours qualified as localized, organ-confined and low-grade cancers, possibly amenable to focal ablative approaches. • The limitations of the present study include its descriptive and retrospective nature.

• While unifocal prostate cancers were most commonly localized to the prostate, half of these patients were associated with intermediate- or high-grade disease. • High-risk features including ECE, SVI, lymph node invasion (LNI), and large tumour volume were identified in a third of patients. • Further studies assessing predictors beyond focality will be needed to determine whether patients can be identified before surgery who might be suitable candidates for lesion-ablative therapies.