Prostate Cancer: Avoidance of Overuse of Bone Scan for Staging Low Risk Prostate Cancer Patients

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Multiple studies have indicated that a bone scan is not clinically necessary for staging prostate cancer in men with a low (or very low) risk of recurrence and receiving primary therapy. For patients who are categorized as low-risk, bone scans are unlikely to identify their disease. Furthermore, bone scans are not necessary for low-risk patients who have no history of bony involvement or if the clinical examination suggests no bony involvement. Less than 1% of low-risk patients are at risk of metastatic disease.

While clinical practice guidelines do not recommend bone scans in low-risk prostate cancer patients, overuse is still common. An analysis of prostate cancer patients in the Surveillance, Epidemiology and End Results Medicare database diagnosed from 2004-2007 found that 43% of patients for whom a bone scan was not recommended received it (Falchook, Hendrix, & Chen, 2015). The analysis also found that the use of bone scans in low-risk patients leads to an annual cost of $4 million dollars to Medicare. The overuse of bone scan imaging for low-risk prostate cancer patients is a concept included on the American Urological Association's (AUA) list in the Choosing Wisely Initiative as a means to promote adherence to evidence-based imaging practices and to reduce health care dollars wasted (AUA, 2019). This measure is intended to promote adherence to evidence-based imaging practices, lessen the financial burden of unnecessary imaging, and ultimately to improve the quality of care for prostate cancer patients in the United States.

For symptomatic patients and/or those with a life expectancy of greater than 5 years, bone imaging is appropriate for patients with unfavorable intermediate-risk prostate cancer, high-risk and very-high-risk prostate cancer (National Comprehensive Cancer Network, 2022) (Evidence Level: Category 2A).

Clinicians should not perform routine bone scans in the staging of asymptomatic very low- or low-risk localized prostate cancer patients (AUA, American Society for Radiation Oncology, & Society of Urologic Oncology, 2017) (Strong Recommendation; Evidence Level: Grade C).

Very low-risk or low-risk patients are unlikely to have disease identified by bone scan. Accordingly, bone scans are generally unnecessary in patients with newly diagnosed prostate cancer who have a PSA <10.0 ng/mL and a Gleason score less than 7 unless the patient’s history or clinical examination suggests bony involvement. Progression to the bone is much more common in advanced local disease or in high-grade disease that is characterized by fast and aggressive growth into surrounding areas such as bones or lymph nodes (AUA, 2019).

Risk Strata Definitions: Very Low, Low, Intermediate, High, or Very High

Very Low/Low Risk - PSA < 10 ng/mL; AND Gleason score 6 or less/Gleason grade group 1; AND clinical stage T1 to T2a.

Intermediate Risk - PSA 10 to 20 ng/mL; OR Gleason score 7/Gleason grade group 2-3; OR clinical stage T2b to T2c.

High/Very High Risk - PSA > 20 ng/mL; OR Gleason score 8 to 10/Gleason grade group 4-5; OR clinically localized stage T3 to T4 (adapted from the National Comprehensive Cancer Network, 2018).

External beam radiotherapy - external beam radiotherapy refers to 3D conformal radiation therapy, intensity modulated radiation therapy, stereotactic body radiotherapy, and proton beam therapy.

Bone scan - bone scan refers to the conventional technetium-99m-MDP bone scan as well as 18F-NaF PET (or PET/CT) scan.

All patients, regardless of age, with a diagnosis of prostate cancer

All patients, regardless of age, with a diagnosis of prostate cancer

All patients, regardless of age, with a diagnosis of prostate cancer