Dr. Karnes reviewed three publications, analyzing [11C] Choline. The first of which, published in Journal of Urology in 2013, was a retrospective review of 176 patients from 2007-2010 that utilized [11C] Choline PET/CT to analyze biochemical recurrence after initial treatment. [11C] Choline PET/CT findings were validated by conventional imaging (57%), biopsy +/- surgical resection (41%), or response to selective radiation (1%). In patients who were initially treated with radical prostatectomy and who had biochemical recurrence, [11C] Choline PET/CT had a sensitivity and specificity of 95% and 86%, respectively. Additionally, the positive predictive value and negative predictive value was 94% and 89%, respectively. PSA cut off for a positive scan was estimated to be 1.7 ng/ml with positivity correlated to increasing PSA value. Optimum PSA value was determined between 1.7-2.0 ng/ml, however EAU guidelines [11C] Choline PET/CT for PSA ≥ 2.0 ng/ml. It was estimated that [11C] Choline PET/CT enhances the rate of detection by ~30% over conventional imaging and subsequently, in 2012, the FDA approved [11C] Choline PET/CT for use became listed in the NCCN guidelines for patients with persistently positive PSA or PSA recurrence.
A second study published in Journal of Urology in 2016 mapped recurrence patterns with [11C] Choline PET and multiparametric MRI for 260 patients treated with radical prostatectomy who had biochemical recurrence. The mean time from biochemical recurrence to identification of disease was only 15 months. Two-thirds of patients had recurrence confined to the pelvis without other sites of distant metastasis.
Finally, 550 patients from 2008-2016 with post radical prostatectomy biochemical recurrence were studied with a 3 tesla mpMRI and [11C] Choline PET. Most metastatic recurrences were detected at a median PSA was 3.3 ng/ml. Patients were treated with ADT (20%), radiation therapy (37%), or radiation + ADT (44%). Of 970 mapped relapse sites, >90% in each cohort were low volume by CHAARTED criteria. Local recurrences were present but lower with postoperative radiation therapy (33% vs 10%). Approximately 50% of recurrences were within the pelvis compared to 66% in the radical prostatectomy only cohort.
The oncologic impact of [11C] Choline PET/CT was then brought into question. A study of 117 patients from 2009-2015 who had biochemical recurrence after radical prostatectomy with node positive disease on evaluation of [11C] Choline PET/CT underwent bilateral salvage pelvic or retroperitoneal lymph node dissections. Around 50% of these patients had normal conventional imaging. Patients had a 31% 5yr biochemical recurrence free survival and 97% 5-year cancer specific morality free survival.
The STOMP trial randomized patients with oligometastatic disease to radiotherapy or surgery. Patients treated with metastasis directed therapy had a 75% PSA decline compared to 35% on surveillance and a statistically significant improvement in biochemical recurrence free survival. The median ADT-free survival was 13 months vs 21 months.
This excellent presentation synthesized existing data on [11C] Choline PET/CT while we await outcomes to fuel unique opportunities in the realm of prostate cancer and biochemical recurrence.
Presented by: R. Jeffrey Karnes, MD, Mayo Clinic
Written by: David B. Cahn, DO, MBS, @dbcahn, Fox Chase Cancer Center, Philadelphia, PA at the 18th Annual Meeting of the Society of Urologic Oncology, November 20-December 1, 2017 – Washington, DC
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