ASCO GU 2023: Patterns of Failure with 18F-DCFPyL PSMA PET/CT in the Post-Prostatectomy Setting: A Regional Cohort Analysis

( 2023 GU ASCO annual meeting included a session on prostate cancer, featuring a presentation by Dr. Samantha Sigurdson discussing patterns of failure with 18F-DCFPyL PSMA PET/CT in the post-prostatectomy setting.

The participants are patients enrolled in the PSMA-PET Registry for Recurrent Prostate Cancer (PREP) who were referred for 18F-DCFPyL PET/CT at Dr. Sigurdson’s institution in Hamilton, Canada. The Registry is the only funded access to PSMA PET/CT for patients in Ontario.  This analysis includes all men who had a PSMA PET/CT on the Registry between April 2019 and December 2021 and are either node positive, or persistently detectable PSA after initial radical prostatectomy, or biochemical failure after initial radical prostatectomy (PSA >0.1 ng/mL).

 In total 177 men were enrolled on the Registry who met the above criteria, and 169 men had complete pathological information available and were included. The pre-PSMA PET/CT median PSA was 0.27 ng/mL. Overall, the probability of a positive PSMA PET/CT result was 59.4%, and the incidence increased with increasing PSA:

  • PSA <0.2 ng/mL: 39%
  • PSA 0.2-0.39 ng/mL: 45%
  • PSA >= 0.4 ng/mL: 85% 

The sites of recurrence and likelihood of a positive PSMA PET/CT by PSA are as follows: 

recurrence likelihood.jpg

Lymph node and distant metastases were detected more frequently in patients with Grade groups 3-5 and higher pathologic tumor (pT) and nodal (pN1) disease:

recurrence pathological features.jpg

Across all 169 patients, the most common site for lymph node recurrence was in the internal iliac chain (21%), followed by the external iliac (20%), obturator (16%), common iliac (13%), pre-sacral (12%), para-aortic (10%), and peri-rectal (8%) chains:

frequency of lymph node recurrence.jpg

 Dr. Sigurdson concluded her presentation discussing patterns of failure with 18F-DCFPyL PSMA PET/CT in the post-prostatectomy setting with the following concluding messages:

  • This prospective study elucidates patterns of failure for prostate cancer patients with biochemical recurrence after radical prostatectomy and could impact management at diagnosis and after radical prostatectomy
  • There is a significant risk of pelvic lymph node positivity on PSMA PET/CT, which emphasizes the importance of including pelvic lymph nodes within salvage radiation volumes

Presented by: Samantha S. Sigurdson, MD, MSc, McMaster University and Juravinski Cancer Centre, Hamilton, ON, Canada

Co-Authors: Khalid al Salman, Aruz Mesci, Theodoros Tsakiridis, Ian S. Dayes, Kimmen Quan, Mira Goldberg, Kara Schnarr, Anil Kapoor, Bobby Shayegan, Glenn Bauman, Katherine Zukotynski, Himu Lukka

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 2023 Genitourinary (GU) American Society of Clinical Oncology (ASCO) Annual Meeting, San Francisco, Thurs, Feb 16 – Sat, Feb 18, 2023.