A single microfocus (5% or less) of Gleason 6 prostate cancer at biopsy--can we predict adverse pathological outcomes?

PURPOSE

Patients with Gleason score 6 microfocal prostate cancer, defined as 5% or less in 1 biopsy core, are often considered to have favorable disease. Few studies have addressed clinical parameters that predict pathological upgrading or up staging at radical prostatectomy.

MATERIALS AND METHODS

From a prospective database of 1,271 consecutive robot assisted laparoscopic prostatectomies performed from 2003 to 2008 patients with Gleason score 6 microfocal prostate cancer were identified. Adverse pathological outcome was defined as any upgrading and/or up staging on prostatectomy pathological findings. Multivariate logistic regression was used to evaluate the ability of patient age, clinical stage, the total number of biopsy cores, preoperative prostate specific antigen, prostate volume and pathological prostate specific antigen density to predict adverse pathological outcomes.

RESULTS

A total of 192 patients with a median age of 59 years (range 42 to 73) were identified with Gleason score 6 prostate cancer involving 5% or less of 1 biopsy core, including 177 (92%) with clinical T1c disease. Mean +/- SD preoperative prostate specific antigen was 6.0 +/- 3.9 ng/ml (range 0.8 to 35). Overall 42 patients (22%) had adverse pathological outcomes, including upgrading in 35 (18%) and up staging in 16 (8%). Multivariate logistic regression revealed that age more than 65 years and pathological prostate specific antigen density greater than 0.20 ng/ml/gm were predictive of an increased risk of adverse pathological results (p = 0.0081 and 0.0169, respectively).

CONCLUSIONS

While a microfocus of Gleason score 6 prostate cancer on biopsy is commonly considered low risk disease, there was a greater than 1/5 risk of pathological upgrading and/or up staging. Patients with Gleason score 6 microfocal prostate cancer should be counseled that they may harbor more aggressive disease, especially when pretreatment clinical risk factors are present, such as advanced age or high clinical prostate specific antigen density.