Predicting bone scan positivity in non-metastatic castration-resistant prostate cancer

Area of Science:

• Oncology
• Urology
• Nuclear Medicine

Background:

• Castration-resistant prostate cancer (CRPC) management requires accurate staging.
• Bone scans are crucial for detecting metastases in CRPC.
• Predictive markers for positive bone scans are needed to optimize patient selection.

Purpose of the Study:

• To evaluate prostate-specific antigen (PSA) levels and kinetic parameters for predicting positive bone scans in non-metastatic CRPC patients.
• To develop predictive tools based on PSA kinetics for bone scan positivity.

Main Methods:

• Retrospective analysis of 531 bone scans from 312 CRPC patients in the SEARCH cohort.
• Generalized estimating equations used to assess associations between patient demographics, pathological features, PSA levels, and PSA kinetics with positive bone scans.
• Development of tables correlating PSA and PSA doubling time (PSADT) with bone scan likelihood.

Main Results:

• Positive bone scans were associated with younger age, higher Gleason scores, higher pre-scan PSA, shorter PSADT, higher PSA velocity, and more remote scan year.
• Scan positivity increased significantly with PSA levels (6% for <5 ng/mL to 57% for ≥50 ng/mL).
• Scan positivity also increased with decreasing PSADT (11% for ≥15 months to 47% for <3 months).

Conclusions:

• PSA levels and kinetics are significant predictors of positive bone scans in CRPC.
• Developed tables using PSA and PSADT can aid in predicting the risk of bone metastasis.
• Combining PSA metrics may improve the selection of CRPC patients for bone scintigraphy.