An Aggressive Approach To An Aggressive Tumor – Role Of Multimodality Treatment In Brainstem Glioma

Abstract

Brain Stem Glioma constitutes 1% to 2% of adult and 10% of pediatric gliomas. Unlike the gliomas in other sites of CNS, brainstems are not amenable for surgery for most of the cases, making radiotherapy a viable treatment option. The median overall survival with conventional fractionated radiotherapy is approximately 10 months. Historical studies done on dose escalation in terms of hypofractionation did not prove any survival benefit. Addition of radiosensitizers did not give an edge over survival, with a median OS of 11.5months. With advances in radiation delivery, efforts have been made to deliver higher dose to the tumor and reducing normal tissue toxicity. We combined both dose escalation and chemotherapy with an intent to improve local control and survival outcomes with acceptable level of toxicities. We recruited 50 patients of Brain Stem Glioma between June 2009 to Dec 2019. All patients underwent DOPA PET and MRI based planning and were treated in 2 phases. Phase 1 was conformal EBRT to a dose of 44Gy in 22 fractions to the volume correlating PET and MR, 39.6Gy in 22 fractions to CTV (1cm expansion from GTV) over 5 weeks. Phase 2 included re-planning with DOPA and MRI based HFSRS boost to residual disease as correlated with PET/MR to a dose 10-12Gy in 2 fractions, to a total BED of 72Gy. All patients received concurrent Temozolomide daily for 45 days throughout the treatment, followed by adjuvant temozolomide of 6-12 cycles. Assessment was done with DOPA/MET PET and MRI every 3 months for 1 year, every 6 months for 2 year and annually thereafter. Overall survival rates were analyzed at the end of 1, 2 and 3 years. In the current sample of 50 patients (19 were pediatric, 31 adults, M:F – 32:18). Age range was 2-73yrs with a median of 27 yrs. The median overall survival was estimated to be 36months CI [3.492-68.51]. The 1-year, 2-year and 3-year survival rate for this group was 61.51%, 56.59% and 40.42% respectively. From our study we conclude that dose escalation and addition of chemotherapy can be considered as a safe and effective treatment in patients with brainstem glioma, with increase in survival as compared to existing literature with acceptable level of toxicities and better preservation of neurological function.