Staging prostate cancer with 68Ga-PSMA-11 PET-CT in the elderly: Focus on the role of pre-imaging biopsy

Abstract Purpose: While PSMA PET-CT has been shown valuable for staging biopsy-proven [B(+)] high-risk prostate cancer (PCa), elderly patients are occasionally referred to PSMA PET-CT without pre-imaging confirming biopsy [B(-)]. The current study evaluates the rate, clinical characteristics, and PET-based stage of B(-) elderly patients, and explores if biopsy status affects therapeutic approach. Methods: One-hundred consecutive patients ≥80 years that underwent staging 68Ga-PSMA-11 PET-CT were included. For each patient, we documented whether pre-imaging biopsy was performed, his clinical parameters, PET-based staging parameters, and the primary therapy he received. Results: Thirty-four (34%) of the elderly patients included in the study had no pre-imaging biopsy. Compared with B(+) patients, B(-) patients were older (median age 87 vs. 82, Pv<0.01), with worse performance status (Pv<0.01), and higher PSA levels (median 57 vs. 15.4 ng/ml, Pv<0.01). On 68Ga-PSMA-11 PET-CT, all B(-) patients had avid disease, with trends towards higher rates of bone metastases (47.1% vs. 28.8%) and overall advanced disease (50% vs. 33.3%) compared with B(+) patients. Among patients with localized (n=36) or locally-advanced (n=25) disease, B(-) patients were less commonly referred to definitive therapies than B(+) patients (Pv<0.01). However, higher age, ECOG PS and PSA were other probable factors determining their therapeutic approach. Among 39 patients with advanced disease, 38 received hormonal therapy, irrespectively of their biopsy status. Among B(-) patients with advanced disease who were referred to hormonal therapy, 12/13 patients with follow-up data showed biochemical and/or imaging-based response. Conclusion: “Real-life” experience with 68Ga-PSMA-11 PET-CT indicates that around one-third of the elderly patients are referred to imaging without pre-imaging confirming biopsy. These patients are likely to be older, with worse clinical status, and higher PSA. Advanced disease might be more likely to be identified on their 68Ga-PSMA-11 PET-CT, and if it does, their biopsy status does not preclude them from receiving hormonal therapy.