Unexpected significant findings non-related to prostate cancer identified using combined prostate-specific membrane antigen positron emission tomography/CT and diagnostic CT scan in primary staging for prostate cancer.

Abstract

There is increasing scientific evidence that whole-body Gallium-68 prostate-specific membrane antigen (68 Ga-PSMA) positron emission tomography/computed tomography (PET/CT) improves the sensitivity of prostate cancer detection above standard staging radiology. Diagnostic IV-contrasted CT scanning offers high-quality recognition and delineation of organs and structures with a high sensitivity and specificity for diagnoses of many non-prostate pathologies. At our institution, imaging for prostate cancer staging and restaging involves a 68 Ga-PSMA PET/CT scan combined with a diagnostic IV-contrasted CT scan of the head, neck, chest, abdomen and pelvis. In this study, we aimed to determine the incidence of significant findings unrelated to prostate cancer identified when this combined imaging approach is utilized for prostate cancer imaging. In this single-centre retrospective review, 68 Ga-PSMA PET/CT and diagnostic IV-contrasted CT scans undertaken for prostate cancer staging over a 12-month period (n=1200) were reviewed for significant findings not related to prostate cancer. In cases with a significant other finding, follow-up imaging and/or pathology results were reviewed, where available. The overall incidence of significant other non-prostate cancer findings was determined, as was the incidence of unsuspected neoplasms. Significant findings, unrelated to prostate cancer, were identified in a total of 5.7% of scans (n=68) with 3.2% (n=38) of findings being unsuspected neoplasms. Diagnostic quality IV-contrasted CT combined with 68 Ga-PSMA PET/CT for staging of prostate cancer identified significant other non-prostate cancer findings, including renal, lung, gastrointestinal and haematological malignancies. Many of these conditions impact on patient management and required further investigation or treatment prior to management of the prostate cancer.