ESTRO 2024 - Abstract Book

S900

Clinical - CNS

ESTRO 2024

Ritika H Hinduja 1 , Venkatesan Kannan 1 , Basant K Mishra 2 , Vivek Anand 1 , Vinay Babu 1 , Sachin Almel 3

1 PD Hinduja National Hospital, Radiation Oncology, Mumbai, India. 2 PD Hinduja National Hospital, Neurosurgery, Mumbai, India. 3 PD Hinduja National Hospital, Medical Oncology, Mumbai, India

Purpose/Objective:

Multifocal presentation of high grade gliomas is rare and is associated with poor outcomes. There are no consensus guidelines for their optimal management and hence treatment is often individualized based on disease extent and patients performance status. The present study is designed to assess the outcomes of multifocal gliomas in a single institution and such data will aid in clinical decision making.

Material/Methods:

Consecutive patients with multifocal high grade glioma planned for radiation therapy in our institution between October 2016 and October 2022 with minimum 1 year follow up were retrospectively analyzed. Multi-focality was determined using T1-weighted MRI sequence, defined as presence of atleast two contrast enhancing lesions. Histology and IDH/ATRX/p53 status was derived from the records and documented. Treatment details (surgery, radiation therapy and chemotherapy), radiotherapy details (sum of GTVs in cc, PTV volume, PTV to brain volume ratio, D2%, V30Gy and V45Gy) were analyzed. Overall survival was calculated from diagnosis. Also, treatment at progression was reviewed.

Results:

Twenty-three consecutive patients with multifocal gliomas were included in the study. Their median age was 57 years, (range 25 to 75 years). The median number of contrast enhancing tumours were 2, with six patients MRI report mentioning multiple (>4) tumours scattered in brain parenchyma. One patient had multiple lesions in the brain and one lesion in the spinal canal (thoracolumbar). 18 patients had grade 4 tumours, 4 had grade 3 tumours while the exact histopathological grade was not known for one patient with a diffuse thalamic lesion. Of the 19 of 23 patients whose molecular histo-pathological reports were available, 3 had an IDH mutation, 1 had loss of ATRX and 10 were p53 mutant. Twenty were primary tumours whereas three were recurrent gliomas with previous presentation 3, 6 and 11 years before present diagnosis. 18 underwent surgical resection prior to radiation therapy, while 4 underwent a stereotactic biopsy and 1 recurrent glioma patient was treated without biopsy as the lesions were close to thalamus. All 23 patients underwent radiation simulation and radiation prescription schedules included 45-60Gy in conventional fractionation to the MRI T1c and T2 abnormal area, except for the patient with multiple brain metastases and spinal metastases. She was planned for cranio-spinal radiotherapy with focal boost to contrast enhancing areas. All were planned using VMAT technique. All but one, started radiation therapy and 18 completed radiation therapy, 17 without interruption. Concurrent and adjuvant temozolamide chemotherapy was prescribed to all the patients. Median volume of the sum of the GTVs for 22 patients (excluding whole brain RT) was 41.3 cm3. Median volume of the PTV was 459.95 cm3 and median PTV to brain ratio was 35.5 percent. Median D2% of the brain was 60.85 Gy (101.4%) (range 40.6Gy to 61.8Gy) and median V30Gy and V45Gy of the brain were 61.58% (range 30.4% to 76.8%) and 41.4 percent (range 0 - 58.4%), respectively. Median survival was 12 months. Six patients deteriorated post radiotherapy within 3 months of completion of treatment. 3 patients survived greater than 3 years. The most common treatment at neuro-radiological progression was addition of bevacizumab to temozolamide. Memory disturbances were seen in 6 patients, significantly affecting their routine activities.