Early detection of recurrent prostate cancer using 18F-DCFPyL PET/CT PET/CT in patients with minimal PSA levels.

Abstract

344 Background: PSMA PET imaging is a highly sensitive and specific imaging tool for detecting prostate cancer, especially in biochemical recurrence (BCR). This has led to growing interest in utilizing PSMA PET for patients with minimally detectable PSA levels following definitive treatment as conventional imaging rarely localizes recurrent disease in this range, potentially delaying diagnosis and appropriate management. However, there is limited literature on the detection rate of 18F-DCFPyL at very low PSA levels in the BCR setting. Methods: This is a pooled retrospective analysis of patients from investigator-initiated trials at West Los Angeles Veterans Affairs and the phase III CONDOR trial with minimal PSA levels. Patients included had 18F-DCFPyL PET/CT at minimal PSA values (0.05 to 0.5 ng/ml). BCR was defined as rising PSA and patients were included irrespective of prior conventional imaging findings. The PET/CT scan reads were assisted by the automated Prostate Cancer Molecular Imaging Standardized Evaluation (aPROMISE) platform. The results were verified by an experienced and independent nuclear medicine physician. Primary analysis focused on the detection rate defined as the number of patients with positive PSMA lesions relative to total number of patients with BCR. Results: In total 129 patients were identified, 36 with PSA levels ranging from 0.05 to 0.2 ng/ml, and 93 with PSA levels >0.2 to 0.5 ng/ml. The site of positive findings, the intensity and volume of uptake in the 18F-DCFPyL PET/CT scan are detailed in the table below. Conclusions: 18F-DCFPyL PET/CT demonstrates high detection rate for recurrent prostate cancer even in patients with minimally detectable PSA levels, highlighting its potential as a valuable tool in early identification of metastatic disease. These findings suggest that current thresholds for initiating PSMA PET/CT imaging in BCR patients may need reconsideration to optimize early detection and subsequent clinical management. Further studies are necessary to refine guidelines and assess the cost-effectiveness of incorporating PSMA imaging at very low PSA levels. 0 – 0.2 (N=36) 0.2 – 0.5 (N=93) Total Detection Rate 13 (36%) 47 (51%) Prostate Bed 3 (8%) 4 (4%) Lymph Node Only 5 (14%) 29 (31%) Lymph Node and Bone 12 (33%) 39 (42%) Bone Only 8 (22%) 14 (15%) Visceral (Lung or Liver) 1 (3%) 10 (11%) Total SUVmean 3.8 4.2 Total SUVmax 10.9 12.4 Total disease volume (mean) 4.9 ml 1.9 ml