(UroToday.com) The 2022 ASCO annual meeting featured a session on prostate cancer, including a presentation by Dr. Loic Djaileb discussing the predictive value of extra-prostatic disease detection by pre-operative PSMA-PET for biochemical recurrence-free survival in patients treated with radical prostatectomy. The goal of this study was to assess this predictive value among patients with intermediate-risk to high-risk prostate cancer included in the prospective trial used for the FDA approval of 68Ga-PSMA-11.
This is a post-hoc follow-up study of the efficacy analysis cohort included in the multicenter prospective phase 3 imaging trial (n = 764; NCT03368547, NCT02611882, NCT02919111) which assessed the diagnostic accuracy of 68Ga-PSMA-11 PET for pelvic nodal metastasis detection prior to radical prostatectomy and pelvic lymph node dissection in patients with intermediate-risk and high-risk prostate cancer. Each PSMA-PET scan was read by three blinded independent readers. Readers assessed the presence of prostate cancer (positive vs negative) by region: prostate bed (T), pelvic lymph nodes (N), extra-pelvic lymph nodes (M1a) bone (M1b), and visceral (M1c). A centralized per-region majority rule was used in case of disagreement. The surgical pathology report was used to assess the presence of pelvic lymph node metastasis by histopathology (pN0 vs pN1). The patients were followed up for biochemical progression after radical prostatectomy by the local investigators using electronic medical records. Biochemical recurrence was defined by a PSA level > 0.2 ng/ml after radical prostatectomy or an initiation of prostate cancer specific adjuvant/salvage therapy. Pairwise comparisons using Log-Rank test was performed to evaluate biochemical recurrence-free survival between the pre-operative PSMA scan reads (N0 M0 vs. N+ and/or M+) and the histopathology status (pN0 vs. pN1).
From December 2015 to December 2019, a total of 764 patients were enrolled in this study, including 277/764 (36%) that underwent radical prostatectomy after PSMA-PET. Clinical follow-up was obtained in 240/277 (87%) patients. The median follow-up time from radical prostatectomy was 21.4 months (IQR 8.80 - 31.53), 100 biochemical recurrence events (41%) were observed, and 98/240 patients underwent salvage therapy or other treatment (40.6%). The biochemical recurrence-free survival was 24.3 (IQR: 7.8 - 48.8) in the whole cohort. With regards to pN and PSMA status:
- pN0/PSMA negative (N0 and M0): 160/240 (66%)
- pN+/PSMA positive (N+ and/or M+): 28/240 (11.6%)
- pN+/PSMA negative (N+ and M0): 39/240 (16%)
- pN0/PSMA positive (N0 and M+); 13/240 (5.4%)
Biochemical recurrence-free survival was higher in PSMA- than in PSMA+ patients (33 vs 7.3 months; p < 0.0001):
Biochemical recurrence-free survival was higher in pN0/PSMA negative than in patients pN+/PSMA negative, pN0/PSMA+ and pN+/PSMA positive: 46 months vs 12.3, 11.7, and 3, respectively (p < 0.001). Biochemical recurrence-free survival did not significantly differ between pN0/PSMA positive and pN+/PSMA negative (11.7 vs 12.3; p = 0.64):
Dr. Djaileb concluded this presentation discussing the predictive value of extra-prostatic disease detection by pre-operative PSMA-PET for biochemical recurrence-free survival in patients treated with radical prostatectomy with the following take-home messages:
- PSMA PET staging information is predictive of biochemical recurrence-free survival after radical prostatectomy
- Patients with extra-prostatic disease detected by pre-operative PSMA-PET scan have a high risk of biochemical relapse after surgery
- Future directions for research include randomized trials powered for clinical outcome and using PSMA PET staging for treatment allocation
Presented by: Loic Djaileb, UCLA Ahmanson Translational Theranostics Division, Los Angeles, CA
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, Chicago, IL, Fri, June 3 – Mon, June 7, 2022.