Long-Term Outcomes in Patients With Isocitrate Dehydrogenase-Mutated Grade 2 Glioma Who Never Received Adjuvant Oncological Treatment After Upfront Mapping-Based Surgical Resection.

Background and objectives: Patients with low-grade glioma (LGG) have a long-life expectancy, especially after initial surgery. However, no report specifically investigated LGG patients who underwent only resection without oncological therapy. In this study, long-run outcomes were analyzed in LGG patients who never received adjuvant treatment after upfront mapping-based surgical resection.

Methods: Inclusion criteria were patients operated on by the author using intraoperative mapping for isocitrate dehydrogenase-mutated grade 2 gliomas, followed at least 3 years with no oncological treatment at last evaluation. Two groups were compared: group 1 comprising stable LGG or progressing very slowly (growth rate ≤1 mm/year) with a simple monitoring and group 2 comprising recurrent LGG (growth rate >1 mm/year), including patients who underwent reoperation(s).

Results: This consecutive series included 111 patients (49 men, mean age 37.3 ± 10.4 years) with epilepsy in 74 cases (66.7%). The mean Karnofsky Performance Scale (KPS) score was 96.5 ± 5.7; 98 patients (88.3%) worked before surgery. The mean preoperative tumor volume (TV) was 21.4 ± 17.2 cm3. The mean postoperative KPS score was 96.7 ± 5.3 (no permanent deficit) with 92 patients who returned to work (93.8%). The mean extent of resection was 98.1 ± 4.7%, with 85 supratotal/total resections (76.6%)-mean residual TV of 0.6 ± 1.6 cm3. There were 60 isocitrate dehydrogenase-mutant astrocytomas (54%) and 51 oligodendrogliomas. Forty-nine patients (44.1%) underwent reoperation(s) without deterioration after 164 resections. The mean follow-up was 8.3 ± 4 years with an overall survival rate of 100%. At final evaluation, 108 patients (97.3%) had a KPS score ≥80 and 79 patients (80.6%) continued to work. In group 1, patients were older (P = .0009) with lower preoperative TV (P = .028), greater extent of resection (P = .002), higher rate of (supra)total resections (P = .024), and lower postoperative TV (P = .0009). The growth rate was higher in patients with reoperation (P < .0001).

Conclusion: Postoperative simple monitoring can be considered in selected patients after upfront mapping-based surgery for LGG, especially when (supra)marginal resection was achieved in tumor with slow growth rate, even after the age of 40 years.