Radiotherapy in Conjunction with Surgical Stabilization of an Impending or Pathologic Fracture Secondary to Metastasis: Is There a Difference between Single and Multifraction Regimens?

Abstract

Patients who undergo surgical stabilization for impending or pathologic fractures secondary to metastasis are often treated with radiotherapy. However, data comparing single and multifraction regimens is limited. We sought to retrospectively examine differences in outcomes between single and multifraction regimens of radiotherapy in this setting. This retrospective study was performed at a single institution. We identified patients that had an impending or pathologic fracture that was secondary to metastasis who underwent surgical fixation in conjunction with either neoadjuvant (within 5 weeks of surgery) or adjuvant (within 10 weeks of surgery) radiotherapy between 2004-2016. Clinical data was abstracted through 12/31/2019. Two-sided T tests were used to compare baseline characteristics between the two patient cohorts. Log-rank regression analysis was then used to analyze length of follow-up for the two cohorts. Finally, Cox survival analysis was used to compare rates of overall survival (OS), local failure (LF), reirradiation, reoperation, and complications. We identified 89 patients with 104 surgical procedures that met our inclusion criteria. 13 patients were alive as of 12/31/2019. Baseline characteristics between the single fraction and multifraction cohorts were similar in regards to age (58.9 vs 57.7, p = 0.68), ECOG (1.70 vs 1.72, p = 0.81), distribution of pathologic fractures (25.9% vs 42%, p = 0.085), distribution of patients treated neoadjuvantly (14.81% vs 26.0%, p = 0.16), rates of synchronous visceral metastasis (63.0% vs 52.0%, p = 0.26), and length of follow-up (20.7 months vs 25.0 months, p = 0.37). Patients in the single fraction cohort did have higher rates of other synchronous bony metastasis (83.3% vs 62%, p = 0.014). The modal and median dose used in the single fraction group was 8Gy/1fx (range 8-12Gy). The modal and median dose fractionation used in the multifraction cohort was 30Gy/10fx (Range 16Gy-39Gy, 5-15fx). When comparing a multifraction treatment course to a single fraction course there was no difference in OS (HR 0.75, CI 0.50-1.13, p = 0.18), LF (HR 0.99, CI 0.99-1.00, p = 0.99), repeat radiotherapy (HR 0.81, CI 0.24-2.68, p = 0.73), re-operation (HR 0.33, CI 0.06-1.71, p = 0.185), or complications (HR 0.74, CI 0.16-3.32, p = 0.69). This is the first study comparing outcomes between single vs multifraction radiotherapy in conjunction with surgical stabilization of an impending or pathologic fracture. We found that there is no difference in rates of OS, LF, repeat radiotherapy, reoperation, or complication between single and multifraction regimens in this setting. Given these findings, we would recommend single fraction radiotherapy as a way to minimize the financial cost and time commitment of treatment.