Anatomically versus biologically unifocal prostate cancer: a pathological evaluation in the context of focal therapy.

Objectives: Since tumor focality in prostate cancer continues to be considered a major limitation for focal prostate therapy, in this study we attempted to compare the pathological features and the proportion of patients with anatomically unifocal versus biologically unifocal tumors (i.e. multifocal prostate cancer in which the secondary nonindex elements are small, low grade and clinically insignificant) who were suitable for focal therapy.

Methods: Ninety-five consecutive whole mount laparoscopic radical prostatectomy samples underwent pathological assessment (from January 2007 to November 2009). Tumor focality, laterality, Gleason score and volume of individual foci, total tumor volume, pathological stage and surgical margin status were assessed. The index lesion was defined as the largest by volume. Patients suitable for focal ablation were defined as having tumors that were unifocal, organ confined, with a Gleason score (GS) up to 7 prostate cancer, or multifocal, organ confined, GS up to 7 prostate cancer, with one large index lesion and the remaining foci demonstrating features of clinically insignificant disease (total tumor volume of all secondary foci ≤0.5 cm(3) with GS ≤ 6).

Results: Patients with biologically unifocal cancer had significantly lower total tumor volume (3.26 versus 7.28 cm(3); p < 0.001), index lesion volume (2.9 versus 7.16 cm(3); p < 0.001), rates of seminal vesicle invasion (4% versus 34%; p < 0.001), rates of positive surgical margins (22.4% versus 52.1%; p < 0.001) and rates of 4+3 GS tumors (10.2% versus 29.1%; p = 0.018). The proportion of patients suitable for focal therapy was higher in the biologically unifocal versus anatomically unifocal cancer group, although without reaching statistical significance (65.3% versus 45.8%; p = 0.11).

Conclusions: Patients with biologically unifocal tumors have better pathological outcome than those with anatomically unifocal disease. At present the assumption that multifocality should a priori exclude patients from any organ-preserving prostate cancer treatment is only theoretical and needs to be validated by future clinical trials since there are a large proportion of patients with multifocal disease apparently suitable for focal prostate therapy.