PSA Levels, Kinetics May Predict PCa Bone Scan Results

PSA levels and kinetics may be used as selection criteria for ordering bone scans for prostate cancer (PCa) patients who experience biochemical recurrence following radical prostatectomy, whether or not they have received androgen-deprivation therapy, according to researchers.

Daniel M. Moreira, MD, of the Arthur Smith Institute for Urology at North Shore Long Island Jewish Health System in New Hyde Park, N.Y., and colleagues analyzed 380 bone scans of 301 hormone-naïve PCa patients and 214 bone scans of 137 PCa patients after receiving androgen-deprivation therapy (ADT). All patients had experienced biochemical recurrence of PCa following radical prostatectomy.

Bone scan positivity was observed in 24 hormone-naïve patients (6%) and 65 ADT-treated patients (30%). In both groups, higher PSA levels, greater PSA velocity, and shorter PSA doubling time (PSADT) were associated with a higher probability of bone scan positivity, Dr. Moreira's team reported in Prostate Cancer and Prostatic Diseases (2014;17:91-96). For the same PSA level and PSADT, ADT-treated patients had higher bone scan positivity than hormone-naïve patients.

With recent advances in chemo- and immunotherapies for metastatic PCa, early detection of metastasis has become increasingly important, the authors noted. “However, it is not clear when and how patients should be screened for metastasis,” they wrote. “Bone scans are routinely used to detect metastasis in patients with prostate cancer; however, a significant number of these scans are negative.”

The investigators noted that their findings suggest that more aggressive and/or advanced disease are associated with a higher risk of a positive bone scan. “Furthermore, they suggest that the factors associated with aggressive and advanced disease such as high PSA levels and short PSADT may be used to stratify patients based on risk of a positive bone scan.”

The researchers created a table combining PSA levels and PSADT to predict the risk of a positive bone scan. For example, among hormone-naïve patients, a PSADT of 9 months or more and a PSA level of 20 ng/mL or higher have a 3% risk of a positive bone scan. By comparison, patients with a PSADT of 3.0-8.9 months and less than 3 months in addition to a PSA level of 20 ng/mL or higher have a 24% and 44% risk of a positive bone scan, respectively.

Among ADT-treated patients, those with a PSADT of 9 months or more and a PSA level of 20 ng/mL or higher have a 39% risk of a positive bone scan. For those with a PSADT of 3.0-8.9 months and less than 3 months, as well as a PSA level of 20 ng/mL or higher, have a 57% and 67% increased risk respectively.

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