Clinical significance of prospectively assigned Gleason tertiary pattern 4 in contemporary Gleason score 3+3=6 prostate cancer

Abstract

Objective: To determine the oncologic impact of prospectively assigned tertiary pattern 4 in contemporary Gleason score (GS) 3 + 3 = 6 radical prostatectomy (RP) specimens.

Patients and methods: Oncologic outcomes were retrospectively reviewed for 720 consecutive patients from a single National Comprehensive Cancer Network (NCCN) center with at least 6 months follow-up after RP for GS3 + 3 = 6 (GS6, N = 222), GS6 with tertiary pattern 4 (GS6t4, N = 62), or GS3 + 4 = 7 (N = 436) prostate cancer, as prospectively graded since 2006 using the 2005 International Society of Urologic Pathologists criteria. Preoperative NCCN risk category, RP pathology, progression-free survival (PFS) and metastasis-free survival (MFS) were compared among the GS6, GS6t4, and GS3 + 4 = 7 groups using χ(2) , Kaplan-Meier, and log-rank analyses.

Results: The incidence of low NCCN preoperative risk classification for GS6t4 patients (63%) was less than that for GS6 patients (77%) while greater than that for GS3 + 4 = 7 patients (30%, P < 0.001). GS6t4 patients had RP pathologic features which were intermediate in risk between that of GS6 and GS3 + 4 = 7 based on extraprostatic extension (27% vs. 6% vs. 31%, respectively, P < 0.001) and mean percentage of prostate gland involvement (13% vs. 10% vs. 16%, respectively, P < 0.001). With a mean overall follow-up of 42 months, PFS for GS6t4 patients (5-year 85%) was intermediate between that of GS6 (5-year 93%) and GS3 + 4 = 7 (5-year 76%) patients (P < 0.001). The 5-year MFS rate was 100% for GS6 and GS6t4 patients compared to 97% for GS3 + 4 = 7 patients (P = 0.07).

Conclusions: This study provides the longest follow-up to date for RP patients with prospectively assigned GS6t4 and supports a risk for adverse RP pathology and postoperative disease progression that is intermediate between GS6 and GS3 + 4 = 7. Whether a tertiary pattern 4 in GS6 disease increases the risk of metastasis is uncertain and requires longer term study. Given favorable oncologic outcomes, less stringent postoperative surveillance for both GS6 and GS6t4 patients may be warranted.

Keywords: biochemical failure; prostate cancer; radical prostatectomy; tertiary Gleason pattern.