How much does Gleason grade of follow-up biopsy differ from that of initial biopsy in untreated, Gleason score 4-7, clinically localized prostate cancer?

OBJECTIVE. To compare histologic grades between an initial biopsy and a follow-up biopsy in untreated, Gleason score (GS) 4-7, clinically localized prostate cancer. METHODS AND MATERIALS. In a prospective single-arm cohort study, clinically localized, GS 4-7, prostate cancer was managed with active surveillance alone, provided that a predefined definition of disease progression was not met. One hundred five (63%) of a total of 168 eligible patients underwent a follow-up prostate biopsy during surveillance. Median time to a follow-up biopsy was 22 months (range: 7-81). Histologic grades between these two biopsies were compared to evaluate the extent of histologic grade change. RESULTS. On the follow-up biopsy, GS was unchanged in 33 patients (31%), upgraded in 37 (35%), and downgraded in 34 (32%). Eleven (10%) had upgrading by 2 Gleason points or more. Eight (8%) had upgrading to GS 8 (none to GS 9 or 10); of these, six were among those with upgrading by 2 Gleason points or more. Twenty-seven (26%) had no malignancy on the follow-up biopsy. Negative follow-up biopsy was more prevalent in patients with a small volume of malignancy in the initial biopsy and a low baseline PSA. CONCLUSIONS. No consistent change in histologic grade was observed on the follow-up biopsy at a median of 22 months in untreated, GS 4-7, clinically localized prostate cancer. Upgrading to GS >= 8 or by 2 Gleason points or more was relatively uncommon.