# Management and Outcome of Recurring Low-Grade Intramedullary Astrocytomas

## TL;DR

This study shows that low-grade spinal cord tumors often recur, but survival remains good, with surgery extent being more important than tumor grade.

## Contribution

The study identifies surgical resection extent as the key factor for outcomes in recurring low-grade spinal cord tumors.

## Key findings

- 53.3% of low-grade intramedullary astrocytomas recurred after initial surgery.
- Large resections (GTR or STR) were associated with better progression-free and overall survival.
- There was no significant difference in survival between WHO grade I and II tumors.

## Abstract

Low-grade intramedullary astrocytomas (LG-IMAs) are rare tumors which are most frequently considered as benign but with high recurrence rates and for which treatment after initial surgery remains unclear. In a single-center cohort including 30 patients with a median follow-up of 59 months (range = 13–376), the recurrence rate of LG-IMA was high (53.3%) and determined by the extent of surgical resection rather than histological grading. The management of recurring tumors was very variable but overall survival at 10 years remained good (81.9%).

Intramedullary astrocytomas (IMAs) are the second most frequent intramedullary tumors in adults. Low-grade IMAs (LG-IMA, WHO grade I and II) carry a better prognosis than high-grade IMAs (HG-IMAs). However, adjuvant treatment of LG-IMAs by radiotherapy (RT) and/or chemotherapy (CT) as well as treatment of tumor recurrences remains controversial. The aim of our study was to evaluate the postoperative outcome of LG-IMAs and the management of recurring tumors. We retrospectively reviewed a series of patients operated on for IMA from 1980 to 2022 in a single neurosurgical department. We retrieved 40 patients who received surgery for intramedullary astrocytomas, including 30 LG-IMAs (22 WHO grade I; 5 WHO grade II; 3 “low-grade”) and 10 HG-IMAs (4 WHO grade III; 5 WHO grade IV; 1 “high-grade”). Of the patients with LG-IMAs, the extent of surgical resection was large (gross or subtotal resection >90%) in 30% of cases. Immediate postoperative radiotherapy and/or chemotherapy was proposed only to patients who underwent biopsy (n = 5), while others were initially followed-up. Over a median follow-up of 59 months (range = 13–376), 16 LG-IMA (53.3%) recurred with a mean delay of 28.5 months after surgery (range = 3–288). These included seven biopsies, five partial resections (PR), four subtotal resections (STR) but no gross total resections (GTR). Progression-free survival for LG-IMAs was 51.9% at 3 years and 35.6% at 5 and 10 years; overall survival was 96.3% at 3 years; 90.9% at 5 years and 81.9% at 10 years. There were no significant differences in terms of OS and PFS between WHO grade I and grade II tumors. However, “large resections” (GTR or STR), as opposed to “limited resections” (PR and biopsies), were associated with both better OS (p = 0.14) and PFS (p = 0.04). The treatment of recurrences consisted of surgery alone (n = 3), surgery with RT and/or CT (n = 2), RT with CT (n = 3), RT alone (n = 2) or CT alone (n = 2). In conclusion, although LG-IMAs are infiltrating tumors, the extent of resection (GTR or STR), but not WHO grading, is the main prognostic factor. The management of recurring tumors is highly variable with no conclusive evidence for either option.