Tertiary Gleason pattern 5 is a powerful predictor of biochemical relapse in patients with Gleason score 7 prostatic adenocarcinoma

In radical prostatectomy specimens Gleason score 7 is among the most commonly assigned scores for prostate carcinoma accounting for 30% to 50% of cases. Gleason score 7 is different from other more differentiated prostate carcinomas (tumors of Gleason scores 5 and 6) with a significantly worse outcome and higher rate of recurrence. Nonetheless, Gleason score 7 tumors are heterogeneous. In this study we examined the differences in clinical outcome between primary Gleason grade 3 and 4 tumors in patients who underwent radical prostatectomy, and determined the influence of tertiary Gleason pattern 5 on patient outcome.

A total of 504 patients underwent radical prostatectomy for prostate cancer and 228 of the patients (45%) had a Gleason score of 7. Cases were analyzed for a variety of clinical and pathological parameters. The influence of primary Gleason pattern and tertiary Gleason pattern 5 on patient outcome was assessed in the Cox regression model.

Among 228 patients with Gleason score 7 prostatic adenocarcinoma, 91 (40%) had a primary Gleason pattern 4 and 137 (60%) had primary Gleason pattern 3. Patients of the former group were more likely to have a higher pathological stage (p = 0.003), more likely to have PSA recurrence (p = 0.02) and more likely to have a tertiary Gleason pattern 5 (p <0.0001). A total of 37 (41%) patients with primary Gleason 4 had a tertiary Gleason pattern 5, whereas only 13 (9%) patients with primary Gleason 3 had a tertiary Gleason pattern 5. In the Cox regression model controlling for tumor stage and surgical margin status, the primary Gleason pattern was not an independent predictor of PSA recurrence (p = 0.80), whereas the presence of tertiary Gleason pattern 5 was a significant predictor of PSA recurrence (hazard ratio 2.10, 95% CI 1.24-3.55, p = 0.006). Five-year PSA recurrence-free survival was 70% for patients without a tertiary Gleason pattern 5 compared to 19% for those patients with a tertiary Gleason pattern 5.

Among patients with Gleason score 7, primary Gleason grade 4 indicates a likelihood of higher tumor stage and higher probability of PSA recurrence than does primary pattern 3. However, it does not independently predict a worse outcome after controlling for other known prognostic parameters associated with disease progression. Regardless of whether the primary Gleason pattern is 3 or 4, a tertiary Gleason pattern 5 is the strongest predictor of a worse outcome in patients with Gleason grade 7 prostatic adenocarcinoma. Therefore, tertiary pattern 5 should be reported in radical prostatectomy specimens.