When to repeat DEXA after starting Denosumab (denosumab)?

From the Guidelines

A repeat DEXA scan is recommended 1-2 years after starting denosumab treatment, as stated in the 2019 ASCO clinical practice guideline 1. Specifically:

• Perform the first follow-up DEXA scan 12-24 months after initiating denosumab therapy, as this allows for assessment of the treatment's effectiveness at its peak effect.
• Subsequent DEXA scans can be done every 1-2 years, depending on individual patient factors and response to treatment, taking into account the bone density result, FRAX calculation, and presence of additional risk factors. When scheduling the repeat DEXA:
• Aim to have it done just before the next scheduled denosumab injection (which is given every 6 months), to evaluate the treatment's effectiveness and guide further management decisions. The rationale for this timing is based on the fact that denosumab rapidly increases bone mineral density (BMD) in the first year, with most patients showing significant BMD improvements within 12-24 months, as supported by the guideline 1. Key considerations:
• Ensure patients are maintaining adequate calcium and vitamin D intake throughout treatment, as this supports optimal bone health and treatment efficacy.
• Repeat DEXA in 2 years or in 1 year if medically indicated, if the bone density result does not demonstrate osteoporosis or significant osteopenia with additional risk factors, and if FRAX calculation does not exceed 10-year risk of hip fracture at 3% or greater, or 10-year risk of non-hip fracture at 20% and/or bone mineral density is not sufficiently low to trigger use of a bone-modifying agent, as recommended by the guideline 1.

From the Research

Repeating DEXA after Starting Denosumab

• The optimal duration of osteoporosis treatment with denosumab is controversial, and there is no clear consensus on when to repeat DEXA scans 2, 3, 4, 5, 6.
• A study published in 2017 suggests that a re-evaluation should be performed after 5 years of denosumab treatment, and patients considered at high fracture risk should either continue denosumab therapy for up to 10 years or be switched to an alternative treatment 2.
• Another study published in 2017 recommends that discontinuation of denosumab should be considered in patients who have been treated for more than 5 years, but close monitoring is suggested due to the possibility of rebound fractures 4.
• A 2023 study suggests that denosumab therapy can be continued for up to 10 years, and the effects are lost rapidly if treatment is discontinued abruptly 5.
• A 2017 observational study found that stopping denosumab after 8 years of continued treatment was associated with bone loss during a 1-year observation study, and treatment to prevent bone loss upon stopping denosumab should be considered 6.

Factors to Consider

• Fracture risk: patients at high fracture risk should either continue denosumab therapy for up to 10 years or be switched to an alternative treatment 2, 4, 6.
• Bone mineral density (BMD): BMD decreases after denosumab discontinuation, and treatment to prevent bone loss should be considered 2, 6.
• Adverse events: denosumab discontinuation may lead to an increased risk of multiple vertebral fractures, and close monitoring is suggested 2, 4, 6.

Monitoring and Follow-up

• Regular DEXA scans should be performed to monitor BMD and fracture risk 2, 4, 6.
• Patients should be closely monitored after denosumab discontinuation due to the possibility of rebound fractures 2, 4, 6.
• Alternative treatments should be considered for patients who discontinue denosumab, especially those at high fracture risk 2, 4, 6.