Background   Bone metastases are considered uncomplicated if they are not causing neurological compromise and have not resulted in and are not at imminent risk for pathological fracture. They are often accompanied by localized pain, which is often controlled at rest but is incident with activity and often difficult to control with analgesics alone. Clinicians may need to advocate for single-fraction (SF) radiation therapy courses for seriously ill patients with refractory pain from uncomplicated bone metastases. This Fast Fact provides guidance for the use of conventional SF radiation treatment for painful bone metastases.  See Fast Fact #66 and Fast Fact #67 for information on standard courses of palliative radiation.

Efficacy and Toxicity A SF radiation treatment for uncomplicated bone metastases has the potential of offering quicker analgesia and lower patient burden in time, cost, and inconvenience than multi-fraction (MF) schedules (1).  Published data suggests that up to 60-93% of patients treated with SF achieve a partial or complete response in pain, meaning significantly lower patient-reported pain scores and decreased use of opioids (2,3). Pain relief can start within 24-48 hours of treatment but typically occurs within 2-3 weeks. Peak analgesia may not occur for 5-6 weeks (2). Patients with a life expectancy less than 1 month may not have sufficient time to warrant even SF radiation therapy for pain relief.

Pediatric Use   One study showed that single-treatment radiation courses were well tolerated and associated with rapid pain relief in 37% of pediatric patients (4). They may also reduce the risk of iatrogenic harm by limiting the need for sedation or general anesthesia.

Comparative Evidence   Dozens of randomized clinical trials and 4 meta-analyses demonstrate similar overall analgesic response rates with SF versus MF radiation therapy (1,4). The duration of follow-up varies between studies with most being limited to 3-12 weeks after treatment completion.  Multiple studies have shown that patients receiving SF were more likely to require re-treatment (20% SF vs 8% MF) (5,6).

Pain Flare   Pain flare is a temporary increase in pain at the treated site and can occur following any radiation schedule. A pain flare develops in 30-40% of patients shortly after treatment and generally resolves within a few days (7). Patients should be given anticipatory guidance about pain flares to avoid misattributions of worsening cancer or a failure of radiation therapy.  Anti-inflammatory based medications such as non-steroidal anti-inflammatories and corticosteroids are recognized analgesics for radiation-induced pain flares (7,8). One randomized controlled trial of patients receiving SF radiation therapy showed that 8 mg of dexamethasone orally < 1 hour prior to the start of radiation therapy and 8 mg daily 1-4 days thereafter could prevent radiation induced pain flares (5). Another study did not show as clear of an analgesic effect with preventative dexamethasone (9).  Decisions to use dexamethasone in this setting to prevent radiation-induced pain flares must therefore be individualized (10).

Re-Treatment About 55% of patients who live > 1-year develop pain again (typically 18 weeks or more after treatment completion) regardless of the radiation treatment course (11).  If bone pain persists or returns, patients treated with any of the common radiation regimens can be considered for an additional single-fraction 8 Gy radiation retreatment to that site 4-6 weeks status post initial treatment (1,6). Patients usually experience moderate pain relief when re-treated (12).

Cost Analysis One study found that single 8-Gy fraction treatment was less expensive than a 10-fraction course (mean cost $998 vs $2316), even when accounting for re-treatment risk and potential survival differences (14). Use of SF radiation therapy can be a cost-effective choice for the palliation of bone metastases, even compared to chemotherapy or other treatments (13-16).

Use Despite the evidence for SF radiation therapy for uncomplicated bone metastases, it is not often used.  A study of nearly 25,000 U.S patients who received radiation therapy for bone metastases from breast, prostate, and lung cancer showed <5% were treated with a single 8 Gy treatment (17). A Choosing Wisely campaign for the American Academy of Hospice and Palliative Medicine recommends that clinicians advocate and pursue SF for seriously ill patients with an anticipated prognosis > 1 month and uncomplicated painful bone metastases (14). In Canada, the use of SF is likely higher than in the US, but utilization varies substantially between physicians and centers, from 26-73% (19,20).

Stereotactic Body Radiation Therapy (SBRT) is a highly focused radiotherapy technique delivering intense radiation within a submillimeter accuracy, thus limiting toxicity to surrounding healthy tissue (21). There is growing evidence for SF SBRT for bone metastases in select patients but there is no consensus on SF vs MF SBRT dosing (21, 22). While SBRT may augment durability of pain relief from radiation therapy, questions remain about optimal dosing and patient selection. Conventional palliative radiation therapy therefore remains the mainstay of treatment for most bone metastases (23).

References

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Authors’ Affiliations: Mayo Clinic, Jacksonville, FL; Medical College of Wisconsin, Milwaukee, WI.
Conflict of Interest: None.
Version History:  Originally edited by Sean Marks MD; first electronically published in June 2017; reviewed and updated in June 2026.