PSA Nadir and Response Assessment in Metastatic Castration-Sensitive Prostate Cancer

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Response assessment in mCSPC requires a multifaceted approach incorporating PSA monitoring, clinical evaluation, and strategic imaging. PSA is a valuable biomarker for treatment response, with multiple studies demonstrating the prognostic significance of achieving a 6-month PSA nadir of ≤ 0.2 ng/mL. Recent data suggest even greater benefit from achieving ultralow PSA levels of ≤ 0.02 ng/mL, with faster PSA decline correlating with improved patient outcomes. Although PSA provides important prognostic information, clinicians must also monitor clinical symptoms, laboratory parameters like alkaline phosphatase, and overall patient well-being.

Imaging strategies in mCSPC differ significantly from castration-resistant prostate cancer, with less clearly defined timepoints for assessment. The choice between conventional imaging (CT scans, bone scans) and advanced prostate-specific maturation antigen PET imaging depends on clinical context, PSA kinetics, and patient symptoms. Many clinicians prefer periodic imaging throughout the mCSPC course to establish baseline comparisons for future progression assessment, typically obtaining imaging around the 1-year mark if patients are responding well, with more frequent imaging if concerns arise.

Integrating clinical status, PSA kinetics, and imaging findings allows for personalized monitoring strategies that balance thoroughness with patient convenience. This comprehensive approach helps distinguish between optimal responders who may benefit from continued current therapy vs those requiring treatment intensification or modification. The evolving understanding of PSA thresholds and their prognostic implications continues to inform clinical decision-making and future trial designs, including studies evaluating treatment escalation based on suboptimal PSA response.