How Does Routine Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography Modify the Current Management of Prostate Cancer? A Multidisciplinary View

Abstract

Background and objective: Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT) and new treatment modalities have expanded the possibilities for diagnosing and managing metastatic prostate cancer, but have also raised questions about their implementation in daily clinical practice. We sought consensus on definitions, preferred imaging modality for staging, and treatment selection in the era of next-generation imaging.

Methods: A modified Delphi method involved two voting rounds and a face-to-face multidisciplinary meeting with 40 Dutch prostate cancer (PCa) experts. Consensus was reached if ≥75% of the panellists chose the same option. Appropriateness was assessed by the RAND Corporation/University of California Los Angeles appropriateness method.

Key findings and limitations: There was consensus on performing metastatic screening with PSMA-PET/CT for unfavourable intermediate- or high-risk PCa. PSMA-PET/CT findings were considered feasible for determining treatment in synchronous metastatic hormone-sensitive prostate cancer, but there was no agreement on the validity of the CHAARTED criteria for interpreting the PSMA-PET/CT findings. If the PSMA-PET/CT findings led to upstaging after conventional imaging, 76% of panellists would opt for treatment intensification. In case of downstaging, 71% would choose for deintensification. Panellists would generally treat patients based on metastatic disease volume as per the CHAARTED criteria, except for bulky low-volume disease (LVD) and LVD with multiple (more than ten) bone metastases, all within the axial skeleton. This would be classified as LVD but treated as high-volume disease. Limitations are that the statements are largely consensus based and originate from a national (Dutch) perspective.

Conclusions and clinical implications: PSMA-PET/CT was considered the preferred modality for initial PCa staging, which is nowadays the standard of care in The Netherlands. The majority of panellists would incorporate PSMA-PET/CT findings for treatment planning, including intensification and deintensification, but the criteria for interpreting metastatic disease volume on PSMA-PET/CT are still uncertain.

Patient summary: A group of Dutch medical specialists discussed on how to diagnose metastatic hormone-sensitive prostate cancer and choose the most appropriate treatment for patients with this condition. It was concluded that imaging based on Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) helps determine appropriate treatment options, with most experts supporting treatment adjustments based on PSMA-PET/computed tomography (CT) results. However, there is still some uncertainty about the criteria for interpreting the extent of metastatic disease with PSMA-PET/CT.

Keywords: Metastatic hormone-sensitive prostate cancer; Molecular hybrid imaging; Prostate cancer; Prostate-specific membrane antigen-positron emission tomography/computed tomography; Systemic therapy.

Fig. 1

Opinions of the panellists on the classification of disease volume (low vs high) and treatment choice according to disease volume (low vs high) for different scenarios. Figures are exclusive of the option “cannot judge” (between 2.5% and 7.5% per question). The following findings were seen on PSMA-PET/CT: scenario 1: multiple pathologically enlarged lymph nodes (more than ten, short axis diameter max 2 cm, all above the iliac and aorta bifurcation); scenario 2: multiple significantly enlarged bulky lymph nodes (short axis 5–7 cm, also above iliac and aorta bifurcation); scenario 3: two bone metastases (L1, acetabulum) and two locoregional lymph nodes (parailiac, below the iliac bifurcation); scenario 4: two bone metastases (L1, acetabulum), two locoregional lymph nodes (parailiac, below the iliac bifurcation), and two lung metastases; scenario 5: two bone metastases (L1, acetabulum), two locoregional lymph nodes (parailiac, below the iliac bifurcation), and two liver metastases; scenario 6: six bone metastases (five spinal metastases L1–4 and one proximal left humerus) and several locoregional lymph nodes (all below iliac bifurcation); scenario 7: ten bone metastases (all within axial skeleton) and several locoregional lymph nodes (all below iliac bifurcation). For all scenarios, PSMA-avid lesions had an anatomical substrate on CT. CT = computed tomography; PET = positron emission tomography; PSMA = prostate-specific membrane antigen.