What is the role of Radiation Therapy (RT) in the treatment of Multiple Myeloma?

Role of Radiation Therapy in Multiple Myeloma

Low-dose radiation therapy (10-30 Gy) is primarily used for palliative treatment of uncontrolled pain, impending pathologic fracture, or impending spinal cord compression in multiple myeloma patients. 1

Indications for Radiation Therapy

Radiation therapy serves several important roles in multiple myeloma management:

1. Pain palliation

   • Primary indication (42% of RT cases) 2
   • Highly effective with complete pain response in 76.4% of patients 2
   • Typically requires 10-30 Gy in fractionated doses 1

2. Prevention/treatment of pathological fractures (28% of RT cases) 2

   • Used for impending fractures in weight-bearing bones
   • Should be combined with orthopedic consultation 1

3. Spinal cord compression (10% of RT cases) 2

   • Emergent indication requiring immediate intervention
   • Should be preceded by high-dose dexamethasone (10 mg IV bolus followed by 4 mg IV every 6 hours) 3

4. Extramedullary disease/vital organ involvement (10% of RT cases) 2

Radiation Therapy Approach

Dosing and Administration

• Dose range: 10-30 Gy 1
• Typical palliative regimens:
  • 8 Gy in 3 fractions
  • 20-30 Gy in 5-10 fractions 3
• Limited involved fields should be used to minimize impact on:
  • Future stem cell harvests
  • Potential subsequent treatments 1

Effectiveness

• Pain relief achieved in 83.6% of patients (76.4% complete response, 7.2% partial response) 2
• Patient-reported outcomes show 5 times lower total symptom scores with RT compared to no RT 4
• Real-world data shows RT is used in approximately 30% of multiple myeloma patients 5

Important Considerations

Timing and Integration with Systemic Therapy

• RT can be used as an adjunct to palliate symptoms early in diagnosis 5
• RT use increases with advancing lines of therapy, particularly in the 6 months before death 5
• RT should not displace standard care for cancer pain (analgesics) but serve as a complementary treatment 1

Stem Cell Collection Concerns

• Prior RT, even to spine and pelvis, does not significantly decrease median number of peripheral blood stem cells collected for autologous transplant 2
• Inadequacy of stem cell collection occurred in 15% of patients receiving spine/pelvic RT versus 9% with no RT (not statistically significant) 2

Special Situations

• Spinal cord compression: Requires emergent intervention with high-dose steroids and surgical consultation prior to RT 3
• Vertebral compression fractures: Consider vertebroplasty or kyphoplasty alongside RT 1
• Novel approaches: Emerging research on combining low-dose RT with immunotherapy (e.g., pembrolizumab) shows promise for relapsed/refractory disease 6

Practical Algorithm for RT Use in Multiple Myeloma

1. For bone pain:

   • Start with analgesics (paracetamol for mild pain, tramadol/codeine for moderate pain, opioids for severe pain) 3
   • If inadequate pain control or rapid relief needed → RT (10-30 Gy)
   • Monitor pain response using standardized pain scales

2. For impending pathologic fracture:

   • Obtain orthopedic consultation
   • RT (10-30 Gy) to affected site
   • Consider surgical stabilization based on fracture risk

3. For spinal cord compression:

   • Immediate high-dose dexamethasone
   • Urgent surgical consultation
   • RT following surgical assessment
   • Monitor neurological status every 4 hours 3

4. For extramedullary disease:

   • RT (10-30 Gy) to affected sites
   • Coordinate with systemic therapy

RT remains a crucial component in multiple myeloma management despite advances in novel agents, providing effective symptom relief and improving quality of life without compromising future treatment options.