Long-Term Outcomes after Incomplete Resection of Intramedullary Grade II Ependymomas: Is Adjuvant Radiotherapy Justified?

SIMPLE SUMMARY: The long-term outcomes and indications for radiotherapy after incomplete removal of grade II intramedullary ependymomas remain unclear. In this retrospective single-center study including 46 patients, no adjuvant radiotherapy was performed, even after subtotal resection (n = 21/46). Over a median follow-up of 6.5 years, radiological progression of a tumoral remnant was noted in seven patients, including only two who were symptomatic and four who required further treatment. Altogether, progression-free survival was 90% at 5 years and 76.8% at 10 years. Based on our experience, we suggest a management algorithm for patients with grade II intramedullary ependymomas where no adjuvant radiotherapy is proposed on a systematic basis, even after subtotal resection. Whenever the tumor can be safely resected, gross total resection should be the aim; otherwise, subtotal removal without adjuvant radiotherapy seems a reasonable option to maximize patient safety with a low risk of clinical progression. ABSTRACT: Ependymomas are the most common intramedullary tumors in adults. While gross total resection is the aim of surgery, tumor infiltration might limit resection. In cases of subtotal removal, the necessary adjuvant management remains unclear. The aim of our study was to assess the need for adjuvant radiotherapy after an incomplete resection of grade II intramedullary ependymomas (IME-II). We retrospectively reviewed all cases of IME-II operated upon at a single tertiary neurosurgical center from 2009 to 2018. Patients with anaplastic or myxopapillary ependymomas, and patients with a follow-up of less than three years, were excluded. We included 46 patients: 19 (41.3%) had a gross total resection; 21 (45.7%) had a subtotal resection; and 6 (13%) had a partial resection. None of the patients underwent adjuvant radiotherapy. Over a median follow-up of 79 months (range = 36–186), seven patients presented a radiological tumor progression with a mean delay of 50.9 months (range = 18–85), of which two were symptomatic (4.3%). Progression-free survival (PFS) was 90.1% at 5 years and 76.8% at 10 years. The extent of the resection was the only significant risk factor for secondary tumor progression (p = 0.012). Four of the seven patients with recurring IME-II were treated: three patients had a second surgery, leading to two GTR and one STR, followed by radiotherapy in one case, and one patient underwent radiotherapy alone. In this study, the rate of symptomatic progression and retreatment after incomplete resection of IME-II without adjuvant radiotherapy was low, suggesting a conservative approach in such cases.