Introduction
18F-DCFPyL, 18F-NaF and 18F-FDG PET/CT were compared in a prospective cohort of men with metastatic prostate cancer (PCa).
Materials and Methods
67 men (Group 1) with documented metastatic PCa underwent 18F-DCFPyL and 18F-NaF PET/CT and a subgroup of 30 men (Group 2) underwent additional imaging with 18F-FDG PET/CT. The tracers were compared for their detection rates, imaging concordance, associations with Prostate Specific Antigen (PSA), treatment at the time of imaging and castration status.
Results
Overall, 61 men had metastatic disease detected on one or more scans, while 6 men were negative. In Group 1, 18F-NaF detected significantly more metastatic lesions than 18F-DCFPyL (median of 3 lesions versus 2, P = 0.001) even after eliminating benign causes of 18F-NaF uptake. This difference was particularly clear for men receiving treatment (P = 0.005) or who were castrate resistant (P = 0.014). The median percentage of bone lesions that were concordant on 18F-DCFPyL and 18F-NaF was 50%. In Group 2, 18F-DCFPyL detected more lesions than 18F-FDG (median of 5 lesions versus 2, P = 0.0003), regardless of PSA level, castration status or treatment. The median percentage of lesions that were concordant on 18F-DCFPyL and 18F-FDG was 22.2%. This percentage was slightly higher for castrate-resistant than castrate-sensitive men (P = 0.048).
Conclusion
18F-DCFPyL PET/CT is the most versatile of the three PET agents for metastatic PCa however, 18F-NaF detects more bone metastases. Imaging reveals substantial tumor heterogeneity with only 50% concordance between 18F-DCFPyL and 18F-NaF and 22% concordance for 18F-DCFPyL and 18F-FDG. This indicates considerable phenotypic differences among metastatic lesions.