Dose Selection for Multiple Myeloma in Modern Era.

Abstract

The management of multiple myeloma (MM) has evolved over the past 20 years, secondary to novel biologic therapeutics. Radiation therapy remains an important intervention in the management of painful lytic bone lesions. However, the currently used radiation therapy regimens were developed in the pre-biologic therapy era. The goal of this study is to assess the effects of dose and fractionation in pain control for patients with MM in the modern era. We conducted a retrospective study based on data collected from patients who received radiation therapy at our institute between 2007 and 2017. A total of 130 patients (266 treatment sites) were included in this study. Univariate Cox proportional hazards models were used to analyze the association of risk of pain recurrence with treatment characteristics and compute the hazard ratios (HRs). The median follow-up time was 14 months. Patients who received a total dose of 20 to <30 Gy (including 20 Gy) had a significantly lower probability of pain recurrence when compared with those who received <20 Gy (HR, 0.36; 95% confidence interval, 0.14-0.94; P = .0365). There was no statistically significant difference in treatment response or pain recurrence between the different fraction numbers and sizes. However, we noted a trend indicating lower pain recurrence in the group that received 6 to 10 fractions of radiation therapy (P = .06). Among the most commonly used regimens, 8 Gy in a single fraction resulted in a statistically significant increased chance of pain recurrence compared with 20 Gy in 10 fractions and a borderline statistically significant increased chance of pain recurrence when compared with 30 Gy in 10 fractions. Radiation therapy remains highly effective at managing lytic bone lesions in patients with MM, and 6- to 10-fraction treatment courses are equally as effective as longer courses at treating these lesions. Treatment with 20 Gy in 10 fractions resulted in a significantly lower probability of pain recurrence when compared with 8 Gy in 1 fraction.