Clinical drivers for imaging testing in non-metastatic castration-resistant prostate cancer in clinical practice: Results of the IDENTIFICA study.

Introduction: The aim of the study was to describe the clinical drivers that lead physicians to perform imaging tests in search of metastasis in non-metastasic castration prostate resistant cancer (nmCRPC) patients.

Methods: Observational, cross-sectional study conducted at the Departments of Urology of 38 Spanish hospitals. The study included 188 patients diagnosed with nmCRPC who underwent an imaging test for the assessment of metástasis. In one study visit, physicians were requested to specify the clinical factors that led them to perform these tests. The results of the imaging tests and the clinical characteristics of the patients since the time of prostate cancer (PC) diagnosis, were reported. Regression analyses were used to determine predictors of imaging test results.

Results: Prostate-specific antigen (PSA) level was the most important driver to order imaging tests (57.1%), followed by regular follow-up (16.5%) and PSA doubling time (PSADT) (12.0%). Although these drivers were not associated to detection of metastasis, patients with PSA levels ≥20 ng/mL had a greater risk of metastasis than patients with PSA levels <4ng/mL (P=.004) and CRPC patients diagnosed with metastasis (mCRPC) had higher median PSA levels (20.9; interquartile range [IQR]: 6.7-38.6) than nmCRPC (9.1; IQR: 5.0-18.0) (P=.005). Sixty-six percent of the patients did not undergo any imaging test after CRPC diagnosis until the study visit (10.6, IQR: 4.0-19.5 months). Curative-intent treatment at PC diagnosis and Gleason score predicted longer time from PC to CRPC diagnosis.

Conclusions: Physicians based their decisions to order imaging tests for metastasis detection in nmCRPC patients mainly on PSA and PSA kinetics, including the regular follow-up stated by guideline recommendations.