111-In-capromab pendetide imaging using hybrid-γ camera-computer tomography technology is not reliable in detecting seminal vesicle invasion in patients with prostate cancer

In this study, we evaluate the diagnostic utility of a hybrid γ-camera-computer tomography (SPECT-CT) indium-111 (111-In)-capromab pendetide scan in detecting seminal vesicle invasion (SVI) in select patients evaluated for primary surgical treatment of prostate cancer (CaP).

We retrospectively analyzed a prospective database of patients who underwent preoperative SPECT-CT imaging with 111-In-capromab-pendetide as part of a staging evaluation who were subsequently treated with radical surgery in our center. Only patients with clinically localized disease were included. We calculated diagnostic properties of the hybrid scan in detecting SVI compared with final pathology. Regression analyses were performed, including scan and preoperative variables to predict SVI.

We retrieved 50 medical records matching our criteria. Median patient age was 61 years (range 45-74). Most patients had a clinical T1c CaP and biopsy Gleason score of 7 or higher. On final pathology, SVI was found in 12 (24%) specimens and radiotracer signal in the seminal vesicle region was reported in 15 (30%) imaging studies. Hybrid SPECT-CT imaging had a sensitivity of 25%, specificity of 61.9%, positive and negative predictive values of 20% and 74.3%, respectively, for detecting SVI. SPECT-CT results did not contribute significantly to SVI prediction on univariate (P = 0.627) or multivariate (P = 0.754) analyses.

SPECT-CT imaging with 111-In-capromab-pendetide is not reliable in detecting or excluding SVI in this select cohort. High rates of positive radiotracer signals from healthy seminal vesicles raise concerns regarding pharmacologic properties of this radiotracer molecule.