Predictors of Local Control With Palliative Radiotherapy for Multiple Myeloma

• Published in: Clinical lymphoma, myeloma and leukemia myeloma and leukemia, 2024-10
• Main Authors: Gao, Robert W., Fleuranvil, Ralph F., Harmsen, William S., Tao, Randa, Pulsipher, Sydney D., Greipp, Patricia T., Baughn, Linda B., Jevremovic, Dragan, Gonsalves, Wilson I., Kourelis, Taxiarchis V., Stish, Bradley J., Peterson, Jennifer L., Rule, William G., Hoppe, Bradford S., Breen, William G., Lester, Scott C.
• Format: Article
• Language: English
• Subjects: Cytogenetics; Double-hit; Multiple myeloma; Radiotherapy; Triple-hit
• ISSN: 2152-2650; 2152-2669; 2152-2669
• DOI: 10.1016/j.clml.2024.10.004

•Palliative radiotherapy for multiple myeloma provides excellent local control.•High-risk cytogenetics do not impact local control with palliative radiotherapy.•Patients with >3 metastases may benefit from EQD2 ≥20 Gy. We performed a retrospective analysis of patients with multiple myeloma (MM) receiving palliative radiotherapy (RT) and assessed factors associated with local control, with a focus on dose/fractionation and cytogenetics. We included patients who received palliative RT for MM at our institution. Cytogenetics were collected via fluorescence in situ hybridization. Follow-up imaging was used to assess local control. A total of 239 patients with 362 treated lesions were included. Eighty-six (36.0%) patients had high-risk cytogenetics. Most lesions received 20 Gray (Gy) in 5 fractions (131, 36.2%), 8 Gy in 1 fraction (93, 25.7%), or 30 Gy in 10 fractions (48, 13.3%). At a median follow-up of 4.3 years, 4-year local progression was 13.4% (95% confidence interval [CI]: 10.3-17.5). No cytogenetic abnormalities were correlated with local progression, nor were double- and triple-hit status. There was a nonsignificant trend toward association between number of treated lesions and local progression (HR for >3 vs. 1: 2.43 [95% CI: 0.88-6.74], P = .059). Among patients with >3 treated lesions, equivalent dose in 2 Gy fractions ≥20 Gy reduced progression (HR: 0.05 [95% CI: 0.01-0.23], P = .0001). In this large study of patients with MM, modern palliative RT achieved excellent rates of long-term local control. Although there was no dose-response observed in the overall cohort, patients with high volume symptomatic disease may benefit from EQD2 ≥20 Gy. High-risk cytogenetics did not appear to influence radioresponsiveness, and standard radiation doses appear to be effective for all MM patients regardless of cytogenetics. We analyzed factors associated with local progression following palliative radiotherapy for multiple myeloma. We performed a retrospective analysis of 239 patients with 362 lesions treated at our institution. Local progression at 4 years was 13.4%. High-risk cytogenetics were not associated with local progression. In patients with >3 lesions treated, higher dose was associated with improved local control.