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.

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).

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.

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-methyl diphosphonate bone scan as well as 18F-sodium fluoride or prostate-specific membrane antigen (PSMA) 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

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