Survival analysis of malignant epidural spinal cord compression after palliative radiotherapy using Tokuhashi scoring system and the impact of systemic therapy

Background: Previous studies have shown similar clinical outcomes of both single and multi-fraction (Fr) radiation therapy among malignant epidural spinal cord compression (MSCC) patients with poor prognosis; whereas, patients expected to have longer survival may require long-course radiotherapy to prevent local failure. However, such a poor prognosis risk group has not yet been clearly identified for use in daily clinical practice. We examined if the known predictive Tokuhashi scoring system could be adapted in MSCC patients treated with palliative radiation therapy.

Methods: A retrospective review of the treatment outcomes of MSCC patients who received palliative radiotherapy from January 2014 to May 2015 was conducted. The patients were stratified into two groups according to the Tokuhashi scoring system: group 1 (score <9), expected survival <6 months, and group 2 (score >8), expected survival >6 months. Their survival was tested against subsequent systemic therapy (chemotherapy, targeted or hormonal therapy) and other risk factors including age, primary site, visceral metastasis, baseline motor function, prior radiotherapy and radiotherapy fractionation (single or multiple).

Results: The outcomes of 119 patients were studied, 116 (97.5%) patients had already succumbed. The overall median survival was 55 days (range, 4-576 days). Ninety-three patients (78.2%) belonged to group 1. The median dose delivered was 25 Gy in 5 Frs [range, 7 Gy in 2 Frs-40 Gy in 10 Frs (to the cauda equina)]. Only nine patients (7.6%) received single-Fr radiotherapy, all belonging to Tokuhashi group 1. Patients belonging to group 1 had shorter median survival than group 2; 49 and 108 days, respectively (P=0.003). Among all the patients, subsequent systemic treatment [hazard ratio (HR) =0.407; 95% confidence interval (CI), 0.236-0.702; P=0.001], non-visceral metastasis (HR =0.608; 95% CI, 0.387-0.956; P=0.031) and primary lung or breast or prostate cancer (P=0.029) were associated with better survival in multivariate analysis. For patients in group 1, primary breast or prostate cancer (HR =0.264; 95% CI, 0.122-0.572; P=0.001) or lung cancer (HR =0.421; 95% CI, 0.246-0.719; P=0.002), non-visceral metastasis (HR =0.453; 95% CI, 0.264-0.777; P=0.004), multi-Fr (HR =0.455; 95% CI, 0.217-0.956; P=0.038) and subsequent systemic therapy (HR =0.460; 95% CI, 0.252-0.842; P=0.012) were associated with better survival. The survival of a subset of patients in group 1 without subsequent systemic therapy was dismal (median survival only 40 days) and not altered by radiotherapy schedule (P=0.189).

Conclusions: MSCC comprises a very heterogenous group of patients, even under the Tokuhashi grouping. Systemic therapy or visceral metastasis may be more important prognostic factors. Further studies are necessary to better select the poor prognosis risk group. In clinical practice, single-Fr radiotherapy could be considered in Tokuhashi group 1 patients due to their expected short survival, especially for those without reasonable systemic treatment options.