Zacho HD, et al. – In this prospective study, researchers sought to determine the prognostic value of the bone scan index (BSI) for time to establishment of castration–resistant prostate cancer (CRPC) in consecutive, hormone–naïve patients with newly diagnosed prostate cancer. It was considered that BSI is an independent risk factor for the time from ADT initiation to CRPC in hormone–naïve patients. Remarkably, the significant prognostic factors, in rank order, were M1–status, Gleason grade, and BSI.

Methods

• Eligible patients participated in a prospective, observational, multi–center study of the value of bone scintigraphy (BS) at staging.
• They determined BSI applying the EXINIBoneBSI–software in 208 consecutive patients undergoing androgen deprivation therapy.
• They categorized the presence or absence of bone metastases at staging by BS with or without supplementary imaging.
• They conducted follow–up >5 years after including the last patient.

Results

• In this analysis, 149 of the 208 patients (72%) were diagnosed with castration–resistant prostate cancer during follow–up.
• 20 months was the median time to castration–resistant prostate cancer.
• In patients without castration–resistant prostate cancer, median follow–up time was 4.4 years.
• In univariate analyses, M1 (hazard ratio [HR] 3.00, 95% confidence interval [95%CI] 2.10 – 4.30), Gleason grade (HR 1.53, 95%CI 1.31 – 1.79), and BSI (HR 1.17, 95%CI 1.12 – 1.23) but not PSA significantly predicted time to CRPC (all, p<0.001).
• In multivariate analyses, the predictive values of M1 (HR 2.06), Gleason grade (HR 1.47), and BSI (HR 1.10) were confirmed.
• The obtained data indicate that log–rank test for equality of time to CRPC indicated the significant predictive value of BSI (BSI=0 vs. 01, p<0.001).
• In addition to routine evaluation of M1 vs M0 status BSI contributed to the predictive power.