Insignificant Prostate Cancer: Charateristics and Predictive Factors

Tumor Location and a Tumor Volume over 2.8 cc Predict the Prognosis for Japanese Localized Prostate Cancer

(1) Objective: Our study investigated the prognostic value of tumor volume and location in prostate cancer patients who received radical prostatectomy (RP). (2) Methods: The prognostic significance of tumor volume and location, together with other clinical factors, was studied using 557 patients who received RP. (3) Results: The receiver operating characteristic (ROC) curve identified the optimal cutoff value of tumor volume as 2.8 cc for predicting biochemical recurrence (BCR). Cox regression analysis revealed that a tumor in the posterior area (p = 0.031), peripheral zone (p = 0.0472), and tumor volume ≥ 2.8 cc (p < 0.0001) were predictive factors in univariate analysis. After multivariate analysis, tumor volume ≥ 2.8 cc (p = 0.0225) was an independent predictive factor for BCR. Among them, a novel risk model was established using tumor volume and location in the posterior area and peripheral zone. The progression-free survival (PFS) of patients who met the three criteria (unfavorable group) was significantly worse than other groups (p ≤ 0.001). Furthermore, multivariate analysis showed that the unfavorable risk was an independent prognostic factor for BCR. The prognostic significance of our risk model was observed in low- to intermediate-risk patients, although it was not observed in high-risk patients. (4) Conclusion: Tumor volume (≥2.8 cc) and localization (posterior/peripheral zone) may be a novel prognostic factor in patients undergoing RP.

Is it possible to predict low-volume and insignificant prostate cancer by core needle biopsies?

In an attempt to minimize overtreatment of localized prostate cancer (PCa) active surveillance (AS) and minor invasive procedures have received increased attention. We investigated the accuracy of pre-operative findings in defining insignificant disease and distinguishing between unilateral/unifocal and bilateral/multifocal PCa. One-hundred and sixty patients undergoing radical prostatectomy were included. Histology reports from the biopsies and matching prostatectomies were compared. Three definitions of insignificant cancer were used: InsigE: tumour volume ≤0.5 mL; InsigW: tumour volume ≤1.3 mL; InsigM: tumour ≤5% of total prostate volume and prostate-specific antigen (PSA) ≤10 ng/mL. In all definitions, Gleason score (GS) was ≤6 and the tumour was organ confined. Biopsies alone performed poorly as a predictor of unifocal and unilateral cancer in the prostatectomy specimens with positive predictive values of 17.8% and 18.9% respectively. Inclusion of other clinical and biochemical parameters did not significantly increase the predictive value. However, the combination of GS ≤ 6, PSA ≤ 10 ng/mL and unifocal or unilateral cancer in biopsy cores resulted in a positive predictive value of 61.1%, 38.9% and 12.0%, respectively, for identifying InsigM, InsigW and InsigE in the prostate specimen. Conclusively, routine prostate biopsies cannot predict unifocal and unilateral PCa, and must be regarded insufficient to select patients for focal therapy. Although candidates for AS may be identified using standard biopsies, a considerable fraction of patients will be understaged. There is a need for more precise diagnostic tools to assess intraprostatic tumour growth.