Delivering a third course of radiation to spine metastases using image-guided, intensity-modulated radiation therapy.
Academic Article
Overview
abstract
OBJECT: The objective of this study was to investigate the feasibility and safety of delivering a third course of radiation to patients with multiply recurrent metastatic disease to the spine. METHODS: Between 2009 and 2011, 10 patients received a third course of radiation to spinal metastases at Memorial Sloan-Kettering Cancer Center using image-guided intensity-modulated radiation therapy (IMRT). Patient and tumor characteristics, dosimetry details, and outcomes were obtained using retrospective chart review. Spinal imaging was performed prior to treatment and at regular follow-up intervals. The cumulative biologically effective dose (BED) to the spinal cord and cauda equina was calculated and was normalized to 2 Gy equivalents (Gy(2/2)). Toxicity and local control were assessed. RESULTS: The median time between the first and second courses of radiation was 18.5 months and the median time between the second and third courses was 11.5 months. The median follow-up from the third course of radiation was 12 months and the median overall survival was 13 months. Pain or neurological symptoms were improved in 80% of patients. The median spinal cord maximum dose normalized BED (nBED) for the whole cohort was 70.73 Gy(2/2) (range 51.9-101.7 Gy(2/2)). The median dose to 5% of the spinal cord D(05) nBED for the entire cohort was 59.4 Gy(2/2). Acute toxicity was most commonly fatigue and dermatitis, with 1 patient experiencing Grade 3 fatigue and 1 patient Grade 3 dermatitis. Late toxicity was limited to 2 cases of Grade 1 dysphagia. There was 1 case of Grade 1 neuropathy and 1 case of Grade 2 neuropathy. The crude rate of local control was 80% with 1 in-field failure and 1 marginal failure. CONCLUSIONS: In this cohort of patients, a third course of IMRT to the spine was well tolerated with no significant late toxicities. Used as salvage therapy for select patients, a third course of radiation is a safe and effective treatment strategy.
