3594 - Efficacy of Palliative Radiation Therapy for Bone Fractures in Multiple Myeloma
Presenter(s)
M. Chan1, L. Redpath2, J. Chan3, C. Martens2, and A. C. Lo4; 1Department of Radiation Oncology, British Columbia Cancer, Vancouver, BC, Canada, 2BC Cancer, Vancouver, BC, Canada, 3Division of Radiation Oncology, The Ottawa Hospital and the University of Ottawa, Ottawa, ON, Canada, 4Division of Radiation Oncology, Department of Surgery, University of British Columbia, Vancouver, BC, Canada
Purpose/Objective(s): Radiation therapy (RT) is known to be an effective palliative treatment in patients with multiple myeloma; however, there is less evidence on the efficacy of RT in fractures specifically. The objective of this study was to assess the benefit of RT in improving pain from fractures in patients with multiple myeloma.
Materials/Methods: A population-based retrospective review was performed in all patients diagnosed with multiple myeloma who received palliative RT for bone fractures between Jan 2016 to Dec 2022. Patients with spinal cord compression at the time of RT were excluded. The study cohort was identified through the provincial cancer registry, and charts were individually reviewed. Descriptive analysis was used to present patient, disease and treatment characteristics. To assess factors affecting pain response, chi-square tests were performed for univariable analysis and logistic regression was used for multivariable analysis.
Results: The study cohort included 557 patients receiving 753 courses of RT. Of the 557 patients, 204 (37%) were female. Median age was 70 years (range: 30-95 years). 453 (60%) RT courses were delivered in the spine, 96 (13%) in the upper extremity, 50 (7%) in the lower extremity, 67 (9%) in the pelvis or sacrum, 11 (1%) in the skull, and 76 (10%) in the thorax. Median EQD2 was 12.0Gy (a/b = 10, range: 3.6 - 44.3Gy). Most common dose fractionations were 8Gy/1# (49%), 20Gy/5# (26%), and 18Gy/5# (6%). Patients were pain-free at baseline prior to 39 courses of RT and post-RT pain assessment was unavailable after 69 courses; for the remaining 645 RT courses, complete resolution of pain was achieved in 153 (24%), partial resolution of pain in 396 (61%) and no pain improvement in 96 (15%). Minimum pain response was 80% for any fracture location. On multivariable analysis, upper extremity (OR 5.46; 95% CI 1.67 – 17.89; P < 0.01) and thorax (OR 2.63; 95% CI 1.00 – 6.91; P < 0.05) fracture location predicted for a greater likelihood of improved overall pain response (partial or complete); however, patient age, gender, and EQD2 RT dose did not.
Conclusion: Palliative RT is effective in patients with bone fractures from multiple myeloma, with the vast majority experiencing complete or partial improvement in pain, irrespective of fracture location or increasing RT dose. Fractures in the upper extremity and thorax are the most likely to respond to palliative RT.
Abstract 3594 - Table 1: Factors associated with pain relief (n=645) a. ribs, sternum, clavicle, scapula| Variable | Odds ratio for partial or complete pain relief | 95% CI | P value | ||
| Age at RT start | 0.99 | 0.98-1.02 | 0.92 | ||
| Gender | Male Female | Reference 1.06 | - 0.67-1.69 | - 0.80 | |
| Fracture location | Spine Upper extremity Lower extremity Thoraxa Pelvis Skull | Reference 5.46 1.02 2.63 0.89 - | - 1.67-17.89 0.43-2.41 1.00-6.91 0.43-1.84 - | - <0.01 0.97 <0.05 0.76 0.99 | |
| EQD2 RT dose (Gy) | 6.25-9.92 9.93–12.39 12.4–20.39 20.4–26.41 32.5–33.22 42.0–44.25 | 0.99 Reference 0.83 0.98 2.85 0.43 | 0.36-2.73 - 0.36-1.95 0.59-1.64 0.36-22.35 0.10-1.81 | 0.98 - 0.67 0.96 0.32 0.25 | |