Genomic Risk Predicts Molecular Imaging-detected Metastatic Nodal Disease in Prostate Cancer

The Decipher genomic classifier (GC) is increasingly being used to determine metastasis risk in men with localized prostate cancer (PCa). Whether GCs predict for the presence of occult metastatic disease at presentation or subsequent metastatic progression is unknown.

To determine if GC scores predict extraprostatic ⁶⁸Ga prostate-specific membrane antigen (⁶⁸Ga-PSMA-11) positron emission tomography (PET) positivity at presentation.

Between December 2015 and September 2018, 91 PCa patients with both GC scores and pretreatment ⁶⁸Ga-PSMA-11 PET scans were identified. Risk stratification was performed using the National Comprehensive Cancer Network (NCCN), Cancer of the Prostate Risk Assessment (CAPRA), and GC scores.

Logistic regression was used to identify factors correlated with PSMA-positive disease.

The NCCN criteria identified 23 (25.3%) and 68 patients (74.7%) as intermediate and high risk, while CAPRA scores revealed 28 (30.8%) and 63 (69.2%) as low/intermediate and high risk, respectively. By contrast, only 45 patients (49.4%) had high-risk GC scores. PSMA-avid pelvic nodal involvement was identified in 27 patients (29.7%). Higher GC score was significantly associated with pelvic nodal involvement (odds ratio [OR] 1.38 per 0.1 units; p=0.009) and any PSMA-avid nodal involvement (pelvic or distant; OR 1.40 per 0.1 units; p=0.007). However, higher GC score was not significantly associated with PSMA-avid osseous metastases (OR 1.11 per 0.1 units; p=0.50). Limitations include selection bias for patients able to receive both tests and the sample size.

Each 0.1-unit increase in GC score was associated with an approximate 40% increase in the odds of PSMA-avid lymph node involvement. These data suggest that patients with GC high risk might benefit from more nodal imaging and treatment intensification, potentially via pelvic nodal dissection, pelvic nodal irradiation, and/or the addition of chemohormonal agents.

Patients with higher genomic classifier scores were found to have more metastatic lymph node involvement on prostate-specific membrane antigen imaging.