ESTRO 2023 - Abstract Book

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ESTRO 2023

Time to hormonal normalization was not significantly different (HR 0. 59 CI 95% (0. 25-1. 4), p=0. 24) between groups. For the subgroup of adenomas close to the optic tract (<2mm), there was no more visual deterioration or visual improvment with HFSRT compared to CRT, at 1 year (p=0,73), 2 years (p=0,99), and 3 years (p=0,89). Toxicity rates were low, and there was no significant difference between the two techniques regarding the incidence of hypopituitarism (p=0. 68). Conclusion Compared to conventional radiotherapy, hypofractionated stereotactic radiotherapy allows a similar rate of local control and hormonal normalization without generating a higher rate of hypopituitarism. It can be used as an alternative for peri optic and < 3cm3 adenomas. However, additional studies are needed for larger adenomas

PO-1140 VMAT based focused RT as an alternative to Stereotaxy in 1-3 brain mets in Oligometastatic Cancers

A. Datta 1 , S. Kundu 2 , J. Bhattacharya 3 , S. Das 4 , A. Pal 5 , A. Kumar 5

1 Netaji Subhas Chandra Bose Cancer Hospital, Radiation Oncology, Kolkata, India; 2 Netaji Subhas Chandra Bose Cancer Hospital, Radiation Oncology, Kolkata, India; 3 APOLLO MULTISPECIALITY HOSPITAL, RADIATION ONCOLOGY, KOLKATA, India; 4 NETAJI SUBHAS CHANDRA BOSE CANCER HOSPITAL, SURGICAL ONCOLOGY, KOLKATA, India; 5 NETAJI SUBHAS CHANDRA BOSE CANCER HOSPITAL, MEDICAL PHYSICS, KOLKATA, India Purpose or Objective To assess the feasibility of VMAT based focused radiotherapy as an alternative of stereotaxy in resource constrained setting. Materials and Methods 31 patients (male – 15, female – 16) of age 32 – 68 years (median– 59 years) with PS 0-2 having Oligometastatic primary (breast, colorectal, NSCLC, melanoma, renal cell carcinoma) with more than 6 months median survival time (MST) calculated by disease specific Graded Prognostic Assessment (GPA) were treated with 30 Gy/5 fractions by Volumetric Arc Therapy (VMAT) from November 2018 to December 2020 in Elekta Synergy linear accelerator. Radiological outcome was assessed by RECIST 1.1 criteria. Toxicities were analyzed by Common Toxicity Criteria for Adverse Effects (CTCAE) v5.0. Neurocognitive evaluation was done by Mini Mental State Examination (MMSE) at completion, 2 weeks and 3 months post Radiotherapy. Time to progression (TTP) of intracranial lesions was calculated from completion of treatment. Results 3 patients were lost to follow up after completion of treatment. After a median follow up of 9 months (range 5 – 18, mean 9.4) 1 patient (Melanoma) had intra cranial disease progression at completion and expired at 5 months. Remaining patients had excellent radiological outcome. The median duration of TTP was 8 months. On univariate analysis, TTP was significantly associated with primary site of malignancy (p = 0.022) and number of brain metastases (p = 0.004). Age, performance status, tumor volumes (GTV and PTV) had no effect on TTP. 3 patients had grade 2 emesis and 2 patients has grade 2 seizures. There were no grade 3 toxicities. There was no neuro-cognitive deficit in any of the patients. Conclusion VMAT offers good intracranial disease control with minimal adverse effects and thus can be used as an alternative to Stereotaxy in 1-3 brain metastases in Oligometastatic disease especially in resource constrained centers. 1 Christiana Care Health System, Department of Radiation Oncology, Newark, USA; 2 Virginia Tech, Department of Statistics, Blacksburg, USA Purpose or Objective The standard of care after resection of a single brain metastasis is to treat the cavity with stereotactic radiation therapy (SRT) to minimize the risk of recurrence. The 2022 ASTRO/ASCO/SNO guidelines recommend stereotactic radiation in one to five fractions. SRT is associated with reduced neurocognitive toxicities as compared to whole brain radiation therapy. However, prospective randomized trials of SRT show higher than expected rates of local recurrence, possibly due to geographic miss. Adding larger target volumes to reduce misses may increase the risk of radiation necrosis. Conformal partial brain irradiation (CPBI) over approximately two weeks is an alternate technique that allows a larger margin of healthy tissue to be safely irradiated, potentially decreasing the risk of tumor recurrence. Materials and Methods Patients receiving post-operative cranial radiotherapy after resection of a brain metastasis from 2015-2022 were eligible for this retrospective single-institution analysis. All SRT patients were treated using a robotic linear accelerator with a median dose of 24 Gy in 3 fractions. The median dose for the CPBI group was 33 Gy in 11 fractions. Information on local control, complications, complete or incomplete resection, radiation treatment modality, cavity location, and years of follow-up was extracted from the charts and a statistical analysis was conducted. Results 57 patients met the eligibility criteria (SRT, n=32; CPBI, n=25). Median follow up was 11 months (SRT, 11 months; CPBI, 10 months). Of the surviving patients, median follow up was 14 months (SRT, 14 months; CPBI, 27.5 months). The crude rate PO-1141 adjuvant radiosurgery versus conformal radiation therapy for resected brain metastases S. Shah 1,1 , S. Rastogi 1 , A. Hanlon 2 , G. Shukla 1