Biological Effective Radiation Dose for Multiple Myeloma Palliation

Area of Science:

• Oncology
• Radiation Oncology
• Hematology

Background:

• Multiple myeloma treatment often involves radiation therapy (RT) for palliation.
• Dose and fractionation schedules for RT in multiple myeloma vary.
• Individualizing RT requires understanding the influence of dose/fractionation and other factors.

Purpose of the Study:

• To review nine years of single-institution RT experience for multiple myeloma.
• To determine the influence of dose/fractionation on palliative outcomes.
• To identify factors for individualizing RT in multiple myeloma patients.

Main Methods:

• Retrospective review of 205 radiation sites in 94 multiple myeloma patients (2012-2021).
• Data captured from treatment planning and clinical records.
• Biological Effective Dose (BED) dichotomized to <24 Gy vs. ≥24 Gy for multivariate analysis using generalized estimating equations.

Main Results:

• RT fractions ranged from 1.8 to 8 Gy over 1 to 25 fractions.
• Most patients experienced complete or very good pain relief (<3% no relief).
• Higher BED (≥24 Gy) courses showed a trend toward better pain control and reduced fracture retreatment risk, with a slight increase in Grade 1 toxicity (20% vs. 12%).

Conclusions:

• Radiation therapy provides effective palliation for multiple myeloma with generally low toxicity.
• BED ≥24 Gy may offer improved pain control and reduced fracture risk, despite a marginal increase in Grade 1 toxicity.
• Individualized RT planning considering BED is crucial for optimizing palliative outcomes in multiple myeloma.