A comparison of 18 F-DCFPyL, 18 F-NaF and 18 F-FDG PET/CT in a prospective cohort of men with metastatic prostate cancer

Introduction: 18 F-DCFPyL, 18 F-NaF and 18 F-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 18 F-DCFPyL and 18 F-NaF PET/CT and a subgroup of 30 men (Group 2) underwent additional imaging with 18 F-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, 18 F-NaF detected significantly more metastatic lesions than 18 F-DCFPyL (median of 3 lesions versus 2, p=0.001) even after eliminating benign causes of 18 F-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 18 F-DCFPyL and 18 F-NaF was 50%. In Group 2, 18 F-DCFPyL detected more lesions than 18 F-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 18 F-DCFPyL and 18 F-FDG was 22.2%. This percentage was slightly higher for castrate-resistant than castrate-sensitive men (p=0.048). Conclusion: 18 F-DCFPyL PET/CT is the most versatile of the three PET agents for metastatic PCa however, 18 F-NaF detects more bone metastases. Imaging reveals substantial tumor heterogeneity with only 50% concordance between 18 F-DCFPyL and 18 F-NaF and 22% concordance for 18 F-DCFPyL and 18 F-FDG. This indicates considerable phenotypic differences among metastatic lesions.