<p class="first" id="d4668284e279">Our objective was to investigate the lesion detection
rate of 18F-DCFPyL PET/CT, a
prostate-specific membrane antigen (PSMA)-targeted PET agent, in patients with biochemically
relapsed prostate cancer after primary local therapy. Methods: This was a prospective
institutional review board-approved study of 90 patients with documented biochemical
recurrence (median prostate-specific antigen [PSA], 2.5 ng/mL; range, 0.21-35.5 ng/mL)
and negative results on conventional imaging after primary local therapies, including
radical prostatectomy (n = 38), radiation (n = 27), or a combination of the two (n
= 25). Patients on androgen deprivation therapy were excluded. Patients underwent
whole-body 18F-DCFPyL PET/CT (299.9 ± 15.5 MBq) at 2 h after injection. The PSMA PET
lesion detection rate was correlated with PSA, PSA kinetics, and original primary
tumor grade. Results: Seventy patients (77.8%) showed positive PSMA PET results, with
a total of 287 lesions identified: 37 prostate bed foci, 208 lesions in lymph nodes,
and 42 in distant sites in bones or organs, Eleven patients had negative results,
and 9 patients showed indeterminate lesions, which were considered negative in this
study. The detection rates were 47.6% (n = 10/21), 50% (n = 5/10), 88.9% (n = 8/9),
and 94% (n = 47/50) for PSA levels of >0.2 to <0.5, 0.5 to <1.0, 1 to <2.0,
and ≥2.0
ng/mL, respectively. In postsurgical patients, PSA, PSA doubling time, and PSA velocity
correlated with PET results, but the same was not true for postradiation patients.
These parameters also correlated with the extent of disease on PET (intrapelvic vs.
extrapelvic). There was no significant difference in the rate of positive scans between
patients with higher-grade and lower-grade primary tumors (Gleason score of ≥4 + 3
vs. <3 + 4). Tumor recurrence was histology-confirmed in 40% (28/70) of patients.
On a per-patient basis, positive predictive value was 93.3% (95% confidence interval,
77.6%-99.2%) by histopathologic validation and 96.2% (95% confidence interval, 86.3%-99.7%)
by the combination of histology and imaging/clinical follow-up. Conclusion: 18F-DCFPyL
PET/CT imaging offers high detection rates in biochemically recurrent prostate cancer
patients and is positive in about 50% of patients with a PSA level of less than 0.5
ng/mL, which could substantially impact clinical management. In postsurgical patients,
18F-DCFPyL PET/CT correlates with PSA, PSA doubling time, and PSA velocity, suggesting
it may have prognostic value. 18F-DCFPyL PET/CT is highly promising for localizing
sites of recurrent prostate cancer.
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