Functional status in long-term survivors after mapping-guided surgery for diffuse low-grade glioma: a consecutive series of 103 patients with a postoperative follow-up of at least 15 years.

Objective: Despite a current overall survival (OS) > 20 years in patients undergoing surgery for diffuse low-grade glioma (LGG), there is no study focusing on functional status in long-term survivors. Here, a unique cohort of LGG patients followed for at least 15 years after mapping-guided resection is reported with analysis of long-lasting outcomes, especially the ability to work.

Methods: Inclusion criteria were LGG patients operated on by the author using intraoperative mapping and follow-up ≥ 15 years after surgery. Long-term functional results were studied by assessing the Karnofsky Performance Scale (KPS) score and professional activity until the last evaluation. Two groups were compared: group 1 comprising patients who continued to work after surgery until the last follow-up, including those who eventually retired because of age; and group 2 comprising patients who did not return to work (RTW) after surgery or who stopped working because of their disease during follow-up.

Results: This consecutive cohort included 103 patients (54 men [52.4%], 49 women [47.6%], mean ± SD age 37.8 ± 7.6 years), including 96 (93.2%) who experienced seizures (and 7 with incidentalomas [6.8%]). The mean preoperative tumor volume was 46.7 ± 35.6 cm3. Three patients (2.9%) had postoperative hemianopia deliberately generated. The mean postoperative KPS score was 94.8 ± 5.7, with 81 patients able to RTW (90%). The mean extent of resection (EOR) was 93.4% ± 7.4%, with 40 supratotal/total resections (38.8%). The mean residual tumor volume was 3.6 ± 5.6 cm3. There were 22 isocitrate dehydrogenase-mutated astrocytomas (21.4%) and 48 oligodendrogliomas (46.6%) (33 gliomas not otherwise specified [32%]). Ten patients (9.7%) received early radiotherapy, which was correlated to a lower rate of RTW (p = 0.05). Sixty-three patients (61.2%) underwent reoperation(s), with a total rate of neurological morbidity of 1.5% after 205 resections. The mean follow-up was 18.2 ± 2.9 years with an OS rate of 83.5%. Among the 86 patients who were still alive at final evaluation, 78 (90.7%) had KPS score ≥ 80. The proportion of patients with KPS score ≥ 80 at last follow-up was lower among irradiated patients (p = 0.005). The mean KPS score was lower before (p = 0.003) and 3 months after (p < 0.00001) surgery in group 2. In group 1, the preoperative (p = 0.046) and postoperative (p = 0.047) tumor volumes were smaller, with greater extent of resection (p = 0.03).

Conclusions: This is the first series of LGG patients who lived ≥ 15 years after mapping-based surgery. These original data show long-term preservation of functional status, including professional activities, particularly in patients with early supratotal/total resection and without radiation therapy.