To review follow-up imaging after equivocal bone scans in men with castration resistant prostate cancer (CRPC) and examine the characteristics of equivocal bone scans that are associated with positive follow-up imaging.

We identified 639 men from five Veterans Affairs Hospitals with a technetium-99m bone scan after CRPC diagnosis, of whom 99 (15%) had equivocal scans. Men with equivocal scans were segregated into “high-risk” and “low-risk” subcategories based upon wording in the bone scan report. All follow-up imaging (bone scans, computed tomography [CT], magnetic resonance imaging [MRI], and X-rays) in the 3 months after the equivocal scan were reviewed. Variables were compared between patients with a positive vs. negative follow-up imaging after an equivocal bone scan.

Of 99 men with an equivocal bone scan, 43 (43%) received at least one follow-up imaging test, including 32/82 (39%) with low-risk scans and 11/17 (65%) with high-risk scans (p = 0.052). Of follow-up tests, 67% were negative, 14% were equivocal, and 19% were positive. Among those who underwent follow-up imaging, 3/32 (9%) low-risk men had metastases vs. 5/11 (45%) high-risk men (p = 0.015).

While 19% of all men who received follow-up imaging had positive follow-up imaging, only 9% of those with a low-risk equivocal bone scan had metastases versus 45% of those with high-risk. These preliminary findings, if confirmed in larger studies, suggest follow-up imaging tests for low-risk equivocal scans can be delayed while high-risk equivocal scans should receive follow-up imaging.

Asian journal of urology. 2019 Jan 18 [Epub]

Brian T Hanyok, Mary M Everist, Lauren E Howard, Amanda M De Hoedt, William J Aronson, Matthew R Cooperberg, Christopher J Kane, Christopher L Amling, Martha K Terris, Stephen J Freedland

Urology Section, Department of Surgery, Veterans Affairs Medical Center, Durham, NC, USA., Urology Section, Department of Surgery, Veterans Affairs Medical Center, Greater Los Angeles, Los Angeles, CA, USA., Departments of Urology and Epidemiology & Biostatistics, University of California, San Francisco, CA, USA., Division of Urology, Department of Surgery, University of California at San Diego Medical Center, San Diego, CA, USA., Division of Urology, Department of Surgery, Oregon Health & Science University, Portland, OR, USA., Urology Section, Division of Surgery, Veterans Affairs Medical Center, Augusta, GA, USA.