Supratotal resection in low grade gliomas (LGGs) : feasibility and clinical impact

Surgical strategy for LGGs aims at maximal tumor removal and at the maintainance of patient full integrity, performing resection according to functional boundaries. Maximal resection is accomplished to reach tumor borders as visibile in volumetric FLAIR (total resection) and when possible even further (supratotal resection). Maximal tumor resection (GTR) is associated with prolonged progression free survival (PFS) and malignant progression free survival (MPFS). While these goals are reached when a GTR is obtained, the feasibility, the clinical and oncological impact of supratotal resection is still a matter of debate. In this work we explore the feasibility of supratotal resection, its short and long term on patient performance, and its oncological impact. A series of 375 LGGS were submitted to surgery according to functional boundaries with intraoperative neurophysiology and neuropsychology. The extent of resection was evaluated on volumetric FLAIR images. The number of cases in which a total or supratotal resection was reached, tumor volume and location, the duration of surgery, the technical adjunts needed, and the rate of surgical complication were assessed. The percentage of immediate and permanent post operative deficits were evaluated by neurologic and neuropsychological evaluation. A separate group of 75 patients submitted to total and supratotal resection were followed up for at least 7 yrs (mean 8 yrs, 7–9 yrs) to evaluate the impact on PFS and MPFS. A total and supratotal resection were obtained in 95 and 94 patients, with tumors located in both dominant and non dominant hemisphere. Supratotal resection was obtained mainly in frontal lobe tumor (52%), but reached also in temporal (20%), insular (20%) and parietal (5%) tumors. Median tumor volume was 18,8 cm3. 33,3% tumors were oligodendroglioma. No difference in term of duration of surgery, technical adjunt needed to perform the procedure, and no complications were registered. The rate of immediate post operative deficits was comparable and related to functional tumor location. No neurological permanent deficits were documented. The neuropsychological evaluation showed a difference at 1 month, with an moderate increase of deficits in the supratotal group, but no differences at 6 months evaluation (10% and 8%, mostly memory and attention deficits). In the group of patients with longer followup no recurrence were observed in the subgroup of patients submitted to supratotal resection while 78% of patients in the subgruop of total resection recurred within 7 years and in 25% showed with malignant transformation. Supratotal resection when performed according to functional boundaries is a feasible and safe procedure to be considered in each case of LGGs. The oncological followup suggests a stronger impact of the supratotal resection on the natural history of the disease wich should be confirmed with a further longer follow up.