ESTRO 2022 - Abstract Book

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Abstract book

ESTRO 2022

28 patients after surgery, in 5 patients for local recurrence and in 3 patients after biopsy. Demographic characteristics of the patients, pathological findings and prognostic factors were estimated. Interval of recurrence or metastasis were calculated from begining of RT. Kaplan Meier method was used for local control(LC) and distant metastasis-free survival(DMFS), progression-free survival(PFS) and overall survival(OS). Cox regression test was used for multivariate analyzes. Results Results: The median age was 41 years and 70% of the patients were male. Supratentorial location was observed in the 80,6% of patients. The most common initial symptoms were pain(42%) and vision problems(14%). The median maximum tumor size was 4.8(1.6-14)cm. Gross total resection(GTR) was performed in 39%, subtotal resection was performed in 50% of the patients. Adjuvant RT was started after a median of 5(2-16)weeks after surgery. Postoperative locally RT was performed in median 60(12-64)Gy and median 30(1-33)fractions. Concurrent temozolamide was administered to 4 patients, sunitinib was administered to one patient and interferon was administered to one patient. Local recurrence in 7 patients and locoregional recurrence in 2 patients were observed in median 58(34-143) months after RT. Reoperation and irradiation was applied to 3 patients, reirradiation to 3 patients and reoperation to 3 patients. Reirradation was administered at a median dose of 40(13.5-54)Gy in 5(1-30)fractions. Systemic treatment due to metastasis was applied in 3 patients in a median 24(22-58) months after RT. Palliative RT was applied to 2 patients. At a median follow-up of 62(6-262)months, the 5-year LC rate was 69.9%, DMFS 86.9%, PFS 63.8% and OS 100%. The precense of residual macroscopic tumor before RT was associated lower LC(p=0.01) and shorter PFS(p=0.04). In the presence of residual tumor before RT, 5-year LC decreases from 100% to 50%, while 5-year PFS decreases from 90% to 46%. However, the effect of residual disease before RT on OS wasn’t statistically significant. Conclusion Conclusion: Adjuvant RT increases LC, especially in patients who cannot undergo GTR. In our study, although macroscopic residual tumor before RT was a factor affecting LC and PFS, but its effect on OS wasn’t demonstrated. The reason for this was considered to be the effectiveness of reoperation and/or reirradation in the presence of recurrence after RT. 1 Seoul national university hospital, Radiation oncology, seoul, Korea Republic of; 2 Seoul national university hospital, Radiation onocology, Seoul, Korea Republic of; 3 Seoul National University Hospital, Hematology and Medical Oncology, , Seoul , Korea Republic of; 4 Seoul National University Hospital, Pathology, Seoul, Korea Republic of; 5 Seoul National University Hospital, Biomedical Research Institute, Seoul, Korea Republic of; 6 Seoul National University Hospital, Radiology, Seoul , Korea Republic of; 7 Seoul National University Hospital, Neurology, Seoul , Korea Republic of; 8 Seoul National University Hospital, Neurosurgery, Seoul, Korea Republic of Purpose or Objective High-grade gliomas, the most common primary brain tumors, are highly lethal and treatment options remain limited. Despite advances in genomic technologies, there are few molecular biomarkers to guide precision medicine for high-grade glioma. Here, we aimed to identify the clinicogenomic features associated with its prognosis and recurrence patterns. Materials and Methods Our single-institution retrospective analysis included 182 patients diagnosed with high-grade gliomas who underwent next- generation sequencing targeting 82 brain tumor-relevant genes. We analyzed clinicopathological status, treatment characteristics, survival, and genomic profiles. Results At a median follow-up of 23 months (range, 2-229 months), 151 patients (83%) had progression or recurrences. Local and distant recurrences were observed in 132 (72.5%) and 101 (54.9%) patients, respectively. The most common genomic variants in high-grade gliomas were TP53 (42.9%), IDH1/2 (23.1%), TERT promoter (38.5%), ATRX (13.2%), H3F3A (7.1%), and SETD2 (6.0%) mutation. Regarding copy number variants, amplification of EGFR (20.9%), PDGFRA (9.9%), MYCN (2.2%) and loss of CDKN2A/2B (49.5%), PTEN (37.9%), RB1 (17.6%), and 1p19q codeletion(9.3%) were the most common copy number aberrations. On multivariate cox regression anlalysis, MYCN amplification (HR 6.08 95% CI 1.91-19.35, p = 0.002), and SETD2 mutation (HR 0.19 95% CI 0.06-0.62, p =0.06) were independent predictors of overall survival, in relation to previously established prognostic factors including age, Eastern Cooperative Oncology Group Performance Status (ECOG PS) scale, extent of resection, MGMT promoter methylation, and IDH1/2 mutation. Interestingly, MYCN amplification (HR 5.24 95% CI 1.69-16.27, p = 0.004), SETD2 mutation (HR 0.35 95% CI 0.12-0.99, p =0.048) were independent predictors of failure from distant recurrences. Homozygous deletion of CDKN2A/2B was associated with an increased risk of local failure. Conclusion The joint analysis of genomic characteristics and pattern of failure for high-grade glioma aids in identifying patients who may benefit from dose or target volume optimization of postoperative radiotherapy. MO-0721 Clinicogenomic predictors for the pattern of failure in high-grade glioma B. Kang 1 , J.H. Lee 2 , T.M. Kim 3 , J. Won 4 , H. Yun 5 , S.H. Choi 6 , S. Lee 7 , S. Park 4 , C. Park 8

MO-0722 Radiation dose-escalation for glioblastoma: who may benefit?

A. Trip 1 , K. Møller Hochreuter 1,2 , M. Høyer 1,2 , J. Folsted Kallehauge 1,2 , S. Lukacova 3