Radiotherapeutic management of adult intraspinal ependymomas

Abstract

Twenty-two adults with ependymomas of the spinal cord were treated with surgery and postoperative radiation between January 1963 and December 1983. The median age was 47 years. Nineteen patients had grade 1 lesions, two had grade 2 and one grade 3. Ten patients had the myxopapillary histologic subtype (all grade 1) and 12 had the cellular variant. There were 15 distal cord lesions originating from the conus medullaris, filum terminale and/ or cauda equina. The remaining seven lesions arose more proximally. Fourteen patients had localized lesions involving one to three vertebral segments, while the remaining eight had extensive ependymomas spanning six to thirteen vertebral segments. The median time from onset of symptoms to diagnosis was 3 years. Surgical treatment consisted of biopsy only in three patients, subtotal removal in eleven patients and total removal in eight patients. Radiation was given to the spine only in all cases. Five patients received whole spine radiation; seventeen received partial spine treatment, appropriate for the length of the primary lesion. The median dose was 5000 cGy (range 3600–5700 cGy). The disease free survival at 5 and 10 years was 81 and 71%, respectively. Overall survival at 5 and 10 years was 95%. Seven of twenty-two (32%) patients failed. Factors analyzed for prognostic significance included age, sex, histology, extent of primary, location of primary within the cord, extent of surgical resection and dose. Too few grade 2 and 3 patients precluded meaningful statistical analysis of grade as a prognostic factor. Neither age, sex, histology, extent of primary, location of primary, nor extent of surgical removal significantly affected disease free or overall survival ( p > 0.05). Four of nineteen (21%) patients with grade 1 lesions failed, while all three patients with grade 2 and 3 lesions did so. Half of the eight patients with extensive ependymomas failed compared to three of fourteen (21%) with limited ones. Six of seventeen (35%) patients failed at doses ≤5000 cGy while only one of five (20%) failed at doses > 5000 cGy. Patterns of failure were analyzed for the seven patients who failed. Six of the seven failures (86% of the failure group, 27% of the overall group) were local, that is, within the initial radiation field at the site of the original tumor. A single patient (grade 2) failed in the posterior fossa while remaining NED in the spinal cord (a head CT scan at initial work-up was negative). One patient (grade 3), who initially failed locally, subsequently developed widespread CNS and distant metastases (involving lungs, kidneys and skin) prior to death. This was the only patient who died of his original disease. Of the remaining six failures, three are alive with disease (at 1, 4 and 7 years), two are alive NED after further treatment (at 1 and 9 years) and one died of metastatic colon CA (at 5 1 2 years) while remaining NED in the spine. Four patients received doses of ≥5500 cGy (range 5500–5700 cGy) to field lengths ranging from 15 to 35 cm. None of these patients has shown evidence of radiation myelopathy at follow-up intervals ranging from 2 1 2 to 11 years. Intraspinal ependymomas in adults are predominantly low grade lesions with a very favorable prognosis. The major pattern of failure is local and our retrospective review suggests improved control can safely be achieved with doses greater than 5000 cGy. We recommend localized treatment to the lesion following subtotal or total surgical removal with shrinking field technique delivering a total dose of 5500 cGy.