BACKGROUND: Osteolytic lesions are present in 75% of multiple myeloma (MM) patients and frequently require palliation with radiation therapy (RT). Case series of MM patients with bone pain undergoing palliative RT suggest doses > 12 Gy (EQD2) provide excellent bone pain relief. However, recent advances in novel biologic agents have significantly improved overall survival and quality of life for MM patients. We hypothesized that lower-dose RT (LDRT, EQD2 < 12 Gy) offers an effective alternative to higher-dose RT (HDRT, EQD2 > 12 Gy) for palliation of painful MM bone lesions.
METHODS: We retrospectively identified MM patients treated with RT for painful bone lesions and stratified by EQD2 < 12Gy versus ≥12Gy. Clinical pain response (CPR) rates, acute and late toxicity, pain response duration, and retreatment rates between LDRT and HDRT groups were analyzed. RESULTS: Thirty-five patients with 71 treated lesions were included: 24 patients (49 lesions) treated with HDRT and 11 patients (22 lesions) with LDRT. Median follow up was 16.8 months. The median dose of HDRT treatment was 20 Gy (range 8-30 Gy, EQD2 12- 32.5 Gy) versus 4 Gy in the LDRT group (range = 4-8 Gy, EQD2 4.67-9.3 Gy). The CPR rate was 98% for HDRT and 95% for LDRT. There was no significant difference in any grade acute toxicity between the HDRT cohort and LDRT cohort (24.5% vs. 9.1%, χ 2 P=0.20). Pain recurred in 10% of lesions (12% HDRT versus 9.5% LDRT). Median duration of pain response did not significantly differ between cohorts (p=0.91). Five lesions were retreated, 2 (9.5%) in the LDRT cohort and 3 (6.3%) in the HDRT cohort.
CONCLUSIONS: In this study, LDRT effectively palliated painful MM bony lesions with acceptable CPR and duration of palliation. These data support prospective comparisons of LDRT versus HDRT for palliation of painful MM bony lesions.
