Comparison of Scans for Detection of Early Biochemical Recurrence of Prostate Cancer After Prostatectomy
In a single-center study reported in The Lancet Oncology, Calais et al found that the use of gallium Ga-68 prostate-specific membrane antigen-11 positron-emission tomography/computed tomography (PSMA PET/CT) resulted in higher detection rates of early biochemical recurrence of prostate cancer after radical prostatectomy in patients with low prostate-specific antigen (PSA) concentrations than fluciclovine F-18 PET/CT.
As stated by the investigators: “National Comprehensive Cancer Networkâ Guidelines consider F-18 PET/CT for prostate cancer biochemical recurrence localization after radical prostatectomy, whereas European Association of Urology guidelines recommend [PSMA] PET/CT.”
Study Details
In the open-label study, conducted at the University of California, Los Angeles, between February 2018 and September 2018, investigators compared prospectively paired F-18 and PSMA PET/CT scans from 50 patients with biochemical recurrence after radical prostatectomy and PSA levels from 0.2 to 2.0 ng/mL. Patients had received no prior salvage therapy.
Patients underwent F-18 and PSMA PET/CT scans within 15 days of each other. The rate of detection of biochemical recurrence by patient and by anatomic region was the primary study endpoint. Each PET scan was analyzed by three independent masked readers, with a consensus majority interpretation being used to determine positive findings. The test for superiority required a 22% difference in detection rates in favor of PSMA PET/CT at the patient level.
Detection Rates
Median follow-up was 8 months. The primary endpoint was met; detection rates were 26% (13 of 50 patients) with F-18 PET/CT vs 56% (28 of 50 patients) with PSMA PET/CT (odds ratio [OR] = 4.8; P = .0026) at the patient level.
By anatomic region, F-18 detection rates were lower than PSMA detection rates for the pelvic lymph node region (4 [8%] of 50 vs 15 [30%] of 50, OR = 12.0, P = .0034) and for any extrapelvic lesions (0 [0%] of 50 vs 8 [16%] of 50, OR = nonestimable; P = .0078). No significant differences in detection rates were observed for individual extrapelvic lesion locations, likely reflecting the small study population. No significant difference was observed in detection rates for prostate bed recurrence (9 [18%] of 50 vs 7 [14%] of 50, OR = 0.6; P = .73).
The investigators concluded, “With higher detection rates, PSMA should be the PET tracer of choice when PET/CT imaging is considered for subsequent treatment management decisions in patients with prostate cancer and biochemical recurrence after radical prostatectomy and low PSA concentrations (≤ 2.0 ng/mL). Further research is needed to investigate whether higher detection rates translate into improved oncological outcomes.”
Jeremie Calais, MD, of the Department of Molecular and Medical Pharmacology, University of California, Los Angeles, is the corresponding author for The Lancet Oncology article.
Disclosures: For full disclosures of the study authors, visit thelancet.com.
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