ESTRO 2020 Abstract Book

S468 ESTRO 2020

Conclusion Post-operative residual GTV ≤70 cc, male gender and younger age group (, 50 years) has been found to have better survival in our analysis. Further study with more number of patients is required to confirm the correlation. PO-0871 Outcomes in Pineal Parenchymal tumours of intermediate differentiation: A single institution study A. Glynn 1 , G. Rangaswamy 1 , J. O'Shea 1 , M. Dunne 1 , C. Faul 1 , D. Fitzpatrick 1 1 St.Luke's Radiation Oncology Network-Dublin-Ireland, Radiation Oncology, Dublin, Ireland Purpose or Objective Pineal parenchymal tumours are rare, accounting for <0.3% of all primary central nervous system tumours. Pineal parenchymal tumour of intermediate differentiation (PPTID) was first classified by the World Health Organisation (WHO) in 2000, as a tumour with an intermediate prognosis, between pineocytoma (WHO grade 1) and pineoblastoma (WHO grade 4). Mitotic index and immunohistochemistry are used to classify PPTIDs as grade II or III pathologically. Their clinical behaviour is variable and they present a risk of seeding to cerebrospinal fluid. Whilst the role of radiotherapy (RT) has been highlighted in various studies, the extent of RT has yet to be determined and the role of chemotherapy remains controversial. The aim of this study was to evaluate clinical outcomes in patients with PPTID who were treated with radical RT at our institution. Material and Methods We conducted a retrospective review of the medical records of patients with PPTID treated at our institution between 2011 and 2018. Clinical data, performance status, histology, imaging reports, type of resection, details of systemic therapy, details of RT, toxicity data, response to treatment and patterns of recurrence were gathered. Results Seven patients with a histological diagnosis of PPTID were identified including four males and 3 females. The median age at diagnosis was 35.7 years (range 15 – 54). Five patients had grade 2 PPTID, 1 patient had grade 3 PPTID and the grade was indeterminate in 1 patient. Three patients had complete resection whilst 4 had subtotal resection. One patient had spinal disease and received craniospinal RT. MRI Spine and CSF cytology were negative in the other 6 patients who received whole brain RT plus a boost to the tumour bed. The median dose was 56 Gy. Four patients had chemotherapy as part of their primary treatment. Three patients progressed one of whom received further stereotactic RT to the recurrent disease in brain and spine and further chemotherapy. Two of these patients died and 1 is currently living with disease. Four patients are alive and well with no evidence of recurrent disease. The median follow up duration was 3.2 years. The median progression free survival was 32.6 months and the overall survival 38.9 months Conclusion PPTID’s constitute 10% of all pineal parenchymal tumours. The aggressiveness of these tumours varies widely and optimal management guidelines are currently lacking. The role of craniospinal RT as well as the optimal RT dose remains a matter of debate. Our study showed that patients who had complete resection and had adjuvant RT and chemotherapy had improved survival compared to those who had subtotal resection. Whole brain RT plus a tumour bed boost seems to confer reasonable tumour control especially in those who had complete excision. A multi-institutional study with a larger patient cohort is required to determine better management guidelines for these rare tumours.

R. Ching Lopez 1 , I. Tovar Martín 1 , R. Del Moral Ávila 1 , A.M. Ruiz Martínez 1 , S. Rodríguez Pavón 1 1 Hospital Universitario Virgen de las Nieves, Radiation Oncology, Granada, Spain Purpose or Objective Craniopharyngiomas are uncommon locally aggressive tumors that are usually located in the sellar and suprasellar regions, which makes their therapeutic approach a challenge. The optimal treatment requires an experienced multidisciplinary team (neurosurgery, radiotherapy, neuro-oncology, endocrinology, ophthalmology). Our aim is to analyze the results of the treatment of craniopharyngiomas with Fractionated Stereotactic Radiotherapy (FSR), by retrospective study of our data. Material and Methods From April 2005 to December 2017, 42 patients with craniopharyngiomas have been treated in our centre. Average age of 31 years (6-72), 64% women and 36% men. Most suprasellar tumors (60%), the main indication for treatment being postoperative residual tumor (65%), with proximity to the optic chiasm in 53%. The dose was 50Gy in 25 fractions (2Gy/fraction, 5 fractions/week), by LINAC with one isocenter and 10 fields. Results The median follow-up was 29 months. At the end of the study, 36.4% stabilization, 42.4% decrease in tumor size and 9.1% complete response. Only 12.1% progression. In relation to the clinical situation, 67.7% stabilization of symptoms and 16.1% improved their quality of life. 16.1% registered clinical worsening. Among the patients with campimetric control, stabilization in 50%, and worsening in 18.8%. 3.6% required rescue treatment. No acute toxicity in 66.7%, being headache the most frequent. In 89.7% no late toxicity. At the end of the study, only one patient died due to the tumor. Conclusion Fractionated Stereotactic Radiotherapy (FSR) is a well- tolerated therapeutic approach with excellent local control, useful in the treatment of intracranial tumors such as craniopharyngiomas. It is useful in the treatment of bulky intracranial tumors and located near critical risk organs. PO-0873 Lung Cancer Brain Metastasis: Higher Biologically Effective Dose Radiotherapy may improve survival. F.A. Lima Aires 1 , E.D. Rodrigues Pinto 1 , M.M.A. Reis Lima Marques 1 , M.G. Pinto 1 1 Centro Hospitalar Universitário de São João, Radioncology, Porto, Portugal ) impact evaluation on specific survival in patients with Brain Metastatic Lung Cancer treated with palliative Radiation Therapy (RT). Material and Methods This retrospective study was based on RT Department electronic health records collected on May 2019. This study was approved by the institutional ethical review board. All patients with Brain Metastastatic Lung Cancer treated with RT between January 2013 and December 2017 were included (n=114). Patients who underwent radiosurgery and brain metastasectomy prior to RT were excluded. Patient, tumour, and treatment characteristics were collected. Biologically relevant covariates, including dose per fraction, number of fractions were used to quantify BED 10 and radiation treatment schedule. The linear-quadratic equation was used to calculate BED 10 and to generate a dichotomous dose variable of ≤30 Gy versus >30 Gy BED 10. Survivals were estimated based on the Kaplan-Meier method and their comparison of survival curves, performed using the log-rank test. An analysis by age group (<70 vs ≥70 years old) was performed. Cox Purpose or Objective Biologically effective dose (BED 10

PO-0872 Craniopharyngiomas treated with Fractionated Stereotactic Radiotherapy (FSR)