Patterns of local failure in patients with high-grade glioma after postoperative radiotherapy with or without chemotherapy

BACKGROUND: To retrospectively analyze the failure patterns of postoperative adjuvant chemoradiotherapy for high-grade glioma (HGG) under the new WHO classification, particularly focusing on relationship of recurrence pattern and molecular subtypes. METHODS: This retrospective study was conducted in Ruijin Hospital of Shanghai Jiaotong University from April 2014 to April 2018. A total of 56 patients diagnosed as WHO III–IV were included. Patients, who underwent pathological typing according to the 2016 WHO Classification of Tumors of the Central Nervous (CNCS), including tumor grade and IDH status. We collected the basic data. The initial relapsed T1 enhancement MRI imaging was transferred and fused to the original treatment planning CT. The tumors were classified as in-field, marginal, or out-field if greater than 80%, 20–80%, or less than 20% of the recurrent volume fell within the 95% isodose line, respectively. RESULTS: The median overall survive was 22.0 months (95% CI: 16.7–27.2). The 1-, 2-, and 3-year survival rates were 85.8%, 43.9%, and 28.8%, respectively. Thirty-three (58.9%) patients progressed with a median progression survival of 15.9 (95% CI: 12.9–19.0) months. Of 33 patients experienced recurrence, 22 (66.7%) had in-field recurrence within a 9.3-month median period (range, 3–32.7 months), and 3 patients (9.1%) were respectively marginal recurrence occurred at 5.9, 6.4, and 15 months, and 6 patients (18.2%) developed out-field progression at a median of 16.1 (4.5–27.1) months, and 2 patients developed both in- and out-field recurrence (6.1%) at 3.2, 4.7 months, respectively. There were16 cases of WHO III, 40 cases of WHO IV, 13 cases of IDH mutation (IDHmt), 30 cases of wildtype (wt) and 13 cases of NOS. The incidence of recurrence of IDHmt (4 cases, 30%) was significantly lower than that of IDHwt (19 cases, 63.3%) and IDH NOS (10 cases, 76.9%) (P=0.001). Local recurrence (in the field and margin) of radiotherapy was 16 cases (84.2%) of IDHwt and 2 cases (50%) of IDHmt type (P=0.05). CONCLUSIONS: In this study, we highlighted the importance of genomic research on identifying local failure patterns and providing recommendations of target delineation for HGG treatment. IDHwt HGG had a higher probability of in-field recurrence after radiotherapy, and RTOG target delineation guide was appropriate, while EORTC guidelines were recommended to IDHmt HGG. Further investigations in prospective randomized clinical trials were warranted to confirm our results.