Follow-up bone scans may be unneeded in prostate cancer patients with low PSAs

Bone scans may no longer be necessary as follow-up in patients with PSA levels less than 5.0 ng/mL, researchers reported in the Journal of Urology (2006; 176:70-4).

Investigators at the Midwest Urology Research Foundation studied data from the Early Prostate Cancer trial that involved 8,113 men diagnosed with localized prostate cancer who received either placebo or bicalutamide (Casodex) in addition to standard care. All men received bone scans regardless of their PSA.

At PSA levels less than 20.0 ng/mL, researchers found a low incidence (.7% to 3.2%) of positive bone scans in patients who were treated with watchful waiting and who were given placebo or bicalutamide. When PSA levels were 20.0 ng/mL or higher, the sample size was small, yet a significant increase in positive bone scans was observed. Regardless of  whether patients received placebo or bicalutamide, those treated with radiation therapy or radical prostatectomy showed a low incidence (.2% to 1.4%) of positive bone scans if their PSA was less than 5.0 ng/mL.

“For those patients treated expectantly after initial therapy, these data clearly suggest that, for PSAs less than 5.0 ng/mL, there is an extremely low likelihood of bone metastasis,” the researchers said. “However, if salvage radiation therapy or salvage cryosurgery is being contemplated, a bone scan will still be necessary as part of the patient evaluation, regardless of PSA.”