Complex treatment of diffuse low-grade glioma - surgery technique and oncological treatment of residual tumors
Abstract
Aim: The aim of our work was retrospective evaluation of the resection extent of predicted and ongoing low-grade glioma (LGG) surgeries. Furthermore, we evaluated the behavior of defined residual tumors after subsequent oncological treatment in case of partial and subtotal resections.
Patients and methods: We evaluated a series of our 37 patients operated on during 2010-2019 at the Department of Neurosurgery, Masaryk Hospital in Ústí nad Labem. The anatomical eloquent boundary lines were strictly defined by the primary motor and visual cortex (g. precentralis and adjacent gyri to the calcarine sulcus), including their tracts, further pars triangularus and pars opercularis of the inferior frontal gyrus as expressive language areas and the structures of the central core.
No absolute eloquent region was the perisylvian cortex of the dominant hemisphere. A partial resection we defined as a presence of the tumor layer > 1 cm evaluated on T2 weighted MRI 2-4 months after surgery.
Subtotal resection was defined identically as tumor layer less or equal to 1 cm. Results: As potentially possible radically resectable (YES), we evaluated an overall 25 patients (68%) in our series with: 1) six patients (16%) with a safe limit to the eloquent area (YES Safe) - in this instance we reached radical resection in all cases; 2) 19 patients (51%) with the necessity of reaching the border to the specific area (YES Risk) - in this instance we reached radical/subtotal/partial resection in 7/6/6 patients.
As necessarily partially resectable (NO), we evaluated 12 patients (32%) and in this instance, we really reached partial resections in all cases. The residual tumor positively reacted to the oncological treatment in 90% of the cases, the shortest period of observation was 13 months.
Major complication of the surgery occurred in one case of a female patient (2.7%). The other complications (5.4%) were mild - one case of hemianopsia and one case of a supplementary motor area lesion.
Conclusion: The definition of anatomical boundaries of LGG and position of eloquent areas correspond with prediction of the extent of gained resection. However, alpha-omega of success is respecting brain arteries and veins in the surgical field.
If a neurosurgeon approaches the margin of safety in an eloquent cortex and its tracts and leaves a small remnant of the tumor during the surgery, radiochemotherapy after surgery is indicated and is effective