The impact of radiosensitivity on clinical outcomes of spinal metastases treated with stereotactic body radiotherapy

BACKGROUND: To evaluate the impact of radiosensitivity on outcomes of spinal metastases treated with stereotactic body radiotherapy (SBRT) and identify the correlated prognostic factors. METHODS: The authors retrospectively reviewed the records of all patients who underwent SBRT with no prior radiation for spinal metastases between October 2015 and October 2020 at Sun Yat‐sen University Cancer Center. On the basis of radiosensitivity, patients were divided into two groups—radiosensitive and radioresistant. The endpoints included local control (LC), overall survival (OS), pain relief, and time to pain relief. RESULTS: A total of 259 (82.5%) patients with 451 lesions were assessable with a median follow‐up time of 10.53 months. The 1‐, 2‐, and 3‐year OS rates were 59%, 52%, and 44%, respectively. The median survival was 33.17 months. Higher Karnofsky Performance Scale score and shorter time to diagnosis of spinal metastases from primary cancer at consult predicted for better OS (p = 0.02 and p < 0.001, respectively). The presence of other metastases (p = 0.04) and pain at enrollment assessed by the Brief Pain Inventory predicted for worse OS (p = 0.01). The 6‐, 12‐, and 24‐month LC rates were 88%, 86%, and 82%, respectively. Younger age was identified for better LC and pain relief (p < 0.001 and p = 0.04, respectively). There was no variable independently associated with time to pain relief. As for toxicity, no Grade ≥3 toxicity was observed. CONCLUSIONS: Regardless of radiosensitivity, SBRT is feasible and appears to be an effective treatment paradigm for patients with spinal metastases, with limited accepted toxicities.