Hippocampal avoidance whole brain radiotherapy in brain metastasis using volumetric modulated arc therapy:
experience from a Regional Cancer Centre of Eastern India

ABSTRACT

Background: Whole-brain radiotherapy is associated with neurocognitive decline and decreased quality-of-life (QOL) among survivors of brain metastasis. Hippocampal-avoidance whole-brain radiotherapy (HA-WBRT) has shown advantage in delaying or preventing the neurocognitive decline while maintaining disease control. This study was done to assess the benefits and feasibility of HA-WBRT in patients with cerebral metastasis in terms of preservation of neurocognitive function and quality of life.

Materials and methods: 27 patients with brain metastasis treated by HA-WBRT and having the records of detailed neurocognitive assessments were analysed from the database of our hospital. The patients were treated with HA-WBRT to a total dose of 30 Gy in 10 fractions with LINAC based IMRT using the VMAT technique. Cognitive function assessment was carried out using “Examination of the Cognitive Functions” scale provided by Bangur-Institute-of-Neurosciences, Kolkata, 2 weeks prior to radiotherapy and post-treatment two-monthly up to 6 months followed by every 3 months till the last follow up. QOL was assessed at the same interval using the Functional Assessment of Cancer Therapy with Brain Subscale (FACT-BR). Follow-up was done till the date of death.

Results: Mean relative cognitive decline percentage decreased over subsequent follow-up visits and was 13% (SD ± 6%), 5% (SD ± 5%), 5% (SD ± 9%) and 2% (SD ± 12%) at 2 months, 6 months, 9 months and 12 months, respectively (p ≤ 0.05). Statistically significant improvement was seen in the mean social-wellbeing (SWB) parameter of QOL (8%. ± 13%, 12%. ± 16%, 7%. ± 20%, no change at 2 months, 4 months, 6 months and 9 months, respectively) (p ≤ 0.05). Mean relative decline in the Emotional-Well Being (EWB) parameter was significant only at 12 months and was 20% (SD ± 35%) (p = 0.04). Mean FACT-BR total Score showed a slight decrease till 9 months from baseline, and then showed a slight improvement up to 12 months.

Conclusion: HA-WBRT is feasible with LINAC-based IMRT using the VMAT technique and beneficial to the patients in preserving neurocognitive function and quality of life without compromising disease control.

Key words: brain metastases; hippocampal sparing WBRT; cognitive functions Rep Pract Oncol Radiother 2023;28(4):468–477

Introduction

Metastatic brain tumors are the most common brain tumors in adults affecting up to 30% of cancer patients. Over the past four decades population-based studies have suggested an incidence rate of approximately 10 per 100,000 population [1–6].

Definitive treatment options for brain metastasis include surgery, whole brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS). By the 1970s, WBRT had become a mainstay treatment for cerebral metastases [7], and while some of its uses are now being supplanted by stereotactic radiosurgery, it remains a beneficial adjunct to other therapies, is used as monotherapy in a variety of clinical situations and is still the treatment of choice in patients with widely disseminated metastases in the brain. However, the main concern regarding the usage of WBRT is the possibility of developing long term neurocognitive deficits (particularly learning and memory) among the treated patients[8].

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