Cost-effectiveness of the implementation of [⁶⁸Ga]Ga-PSMA-11 PET/CT at initial prostate cancer staging

Background: Despite its high specificity, PSMA PET/CT has a moderate to low sensitivity of 40-50% for pelvic lymph node detection, implicating that a negative PSMA PET/CT cannot rule out lymph node metastases. This study investigates a strategy of implementing PSMA PET/CT for initial prostate cancer staging and treatment planning compared to conventional diagnostics. In this PSMA PET/CT strategy, a bilateral extended pelvic lymph node dissection (ePLND) is only performed in case of a negative PSMA PET/CT; in case of a positive scan treatment planning is solely based on PSMA PET/CT results.

Method: A decision table and lifetime state transition model were created. Quality-adjusted life years and health care costs were modelled over lifetime.

Results: The PSMA PET/CT strategy of treatment planning based on initial staging with [⁶⁸Ga]Ga-PSMA-11 PET/CT results in cost-savings of €674 and a small loss in quality of life (QoL), 0.011 QALY per patient. The positive effect of [⁶⁸Ga]Ga-PSMA-11 PET/CT was caused by abandoning both an ePLND and unnecessary treatment in iM1 patients, saving costs and resulting in higher QoL. The negative effect was caused by lower QoL and high costs in the false palliative state, due to pN1_lim patients (≤ 4 pelvic lymph node metastases) being falsely diagnosed as iN1_ext (> 4 pelvic lymph node metastases). These patients received subsequently palliative treatment instead of potentially curative therapy.

Conclusion: Initial staging and treatment planning based on [⁶⁸Ga]Ga-PSMA-11 PET/CT saves cost but results in small QALY loss due to the rate of false positive findings.