Microfocal prostate cancer: biopsy cancer volume does not predict actual tumour volume

To determine whether microfocal prostate cancer on needle biopsy predicts clinically insignificant disease in men undergoing radical prostatectomy.

The records of 726 men who underwent radical prostatectomy between January 1990 and September 1995 were reviewed; 83 men had pre-operative prostatic needle biopsies which revealed microfocal prostate cancer. In these men, tumour volume (length) in the biopsy was compared to the percentage of tumour in the total prostatectomy specimen, and the pathological stage and clinical outcome reviewed.

Of the 83 men with microfocal prostate cancer on biopsy 75 (90%) had clinically significant disease. Pre-operative variables were of no use in identifying patients with clinically insignificant tumour volumes. When comparing those with microfocal tumour and those without at one institution, 69% had organ-confined (pT2) disease and 31% had capsular penetration (pT3), compared with 61% and 39%, respectively (P < 0.05). Additionally, the positive surgical margin rate for those with microfocal tumour was only 6%, compared with 26% for those without microfocal disease (P < 0.05). Biochemical failures during the median follow-up period of 24 months occurred in 6% of the men with microfocal cancer and in 15% of those undergoing total prostatectomy (P < 0.05).

Microfocal prostate cancer determined from the needle biopsy does not predict clinically insignificant disease.