They found that Gleason score at the positive margin was the same as the final pathologic specimen in 44% of patients. On multivariable analysis assessing predictors of BCR after prostatectomy, a low Gleason score positive margin was associated with a 50% decrease in risk of BCR (HR 0.50, 0.25-0.97). However, these findings have only been assessed in a few reports [1-2], and according to the authors there is no consensus as to whether the Gleason score at the margin should be reported in addition to highest Gleason score in the specimen. The objective of this study was to evaluate whether the Gleason score at the positive surgical margin affects the risk of biochemical recurrence following robot-assisted radical prostatectomy.
The authors identified 470 consecutive patients undergoing robot-assisted radical prostatectomy with pelvic lymph node dissection for localized prostate cancer at a single institution. Specimens with a positive surgical margin were reviewed and the Gleason score at the positive margin was compared with the highest Gleason score in the specimens. BCR-free rates were calculated using Kaplan-Meier estimates, with the highest Gleason score and the Gleason score at the positive surgical margin. Cox proportional hazards models including Gleason score, margin length, preoperative PSA level, and pathological stage were used to predict BCR. Individual models were assessed using Gleason score at the margin and highest Gleason score of the specimen, and the models were compared using the concordance index.
Over nearly 20 months of follow-up after robot-assisted radical prostatectomy, there were 55 (11.6%) patients that experienced BCR. Among the 475 patients included in the study, positive margins were identified in 102 (21.5%) patients, and in 26 patients the Gleason score at the positive surgical margin was lower than the highest Gleason score of the specimen. Using Kaplan-Meier estimates, the authors found that Gleason score at the positive surgical margin can stratify BCR-free rates better than the highest Gleason score in the specimen.
Using Cox proportional hazards models, Dr. Kanao and colleagues found that a lower-Gleason score positive margin was significantly associated with a decreased risk of BCR (p=0.039): vs Gleason 3+3 – Gleason 3+4 HR 4.49 (95%CI 0.56-35.9), Gleason 4+3 HR 7.89 (95%CI 0.95-65.7), Gleason ≥8 HR 8.34 (95%CI 1.03-37.5). The concordance index of the model using Gleason score at the positive surgical margin was 0.816, compared to the model using highest Gleason score of the surgical specimen (0.752).
A limitation of this study is that the sample size is much smaller (1/8th) than what was reported by Kates et al. However, these results do validate the finding that the Gleason score at the surgical margin is more prognostic of BCR risk than the highest Gleason score of the surgical specimen following robot-assisted radical prostatectomy. Based on these findings and those reported by others [1-2], Dr. Kanao’s group makes a strong argument for reporting not just the Gleason score of the surgical specimen, but also at the surgical margin.
Presented By: Kent Kanao, Aichi Medical University, Nagakute, Japan
Co-Authors: Miho Sugie, Hiroyuki Muramatsu, Shingo Morinaga, Keishi Kajikawa, Ikuo Kobayashi, Genya Nishikawa, Yoshiharu Kato, Masahito Watanabe, Kogenta Nakamura, Makoto Sumitomo, Nagakute, Japan
References:
1. Kates, M, Sopko NA, Han M, et al. Importance of reporting the Gleason score at positive surgical margin site: Analysis of 4,082 consecutive radical prostatectomy cases. J Urol 2016;195(2):337-342.
2. Savdie R, Horvath LG, Benito RP, et al. High Gleason grade carcinoma at a positive surgical margin predicts biochemical failure after radical prostatectomy and may guide adjuvant radiotherapy. BJU Int 2012;109(12):1794-1800.
Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre Twitter: @zklaassen_md at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA