Effect of radiation on patients with grade 2 intramedullary spine ependymoma

Purpose Spinal ependymomas are rare glial neoplasms. Given the rarity there is a lack of consensus on the use of radiation in these patients. This study aims to investigate the role of adjuvant radiation and identify predictors of functional outcome at last follow-up in patients with histology-confirmed intramedullary ependymomas. Methods We conducted a retrospective cohort study at a single center with 101 patients with histologically confirmed grade 2 spine ependymoma. We aimed to identify which patients benefit most from postoperative radiotherapy by analyzing preoperative features and outcomes in adjuvant RT recipients, and to assess functional outcomes at last follow-up. Patients with subependymomas, conus/filum terminale tumors, or drop metastases were excluded. KNN (K-Nearest Neighbors) matching based on age and sex was used to match patients. Results A total of 101 patients were included in this study, with a mean age of 43.2 years. The cervical spine was the most common location of the tumor (68.3%). The cohort had a median follow-up time of 1.09 (0.34–3.31) years. Nine patients received radiation following tumor resection to prevent recurrence. The median total radiation dose was 4680 cGy (range: 4550–5040 cGy), with a median fractionated dose of 180 cGy (range: 180–200 cGy), delivered over an average of 23.7 ± 7.6 days. After matching, 27 patients were in the no-radiation group and 9 in the radiation group, the mean tumor volumes in the no-radiation and radiation groups were 4.0 ± 5.0 cm³ and 2.8 ± 2.9 cm³, respectively (p = 0.558). Recurrence occurred in two of nine radiation patients and none of the non-radiation patients, with radiation typically reserved for higher-risk clinical scenarios such as residual disease, multiple recurrences, large tumor volume, internal hemorrhage, and subtotal resection. Preoperative symptoms, including pain, sensory symptoms, and weakness, did not differ significantly between the groups (p > 0.05). Preoperatively, there were higher number of functionally dependent patients in the radiation group (22.2%) compared to the no-radiation group (11.1%), although this difference was not statistically significant (p = 0.404). At last follow-up, weakness was more frequent radiation group (55.6% vs. 11.1%, p < 0.005). An exploratory multivariable analysis of the entire cohort revealed postoperative radiation (adj. p = 0.008), was associated with weakness at last follow up. Conclusion Our findings highlight the need to consider radiotherapy carefully and tailor its use on a case-by-case basis in patients with grade 2 ependymoma.