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Conformal whole brain radiotherapy with hippocampal avoidance

Conformal whole brain radiotherapy without hippocampal avoidance

Conformal Whole Brain Radiotherapy 30 Gy in 10 fractions with Hippocampal Avoidance using Intensity modulated radiotherapy, Volumetric arc therapy, or Tomotherapy

Hippocampal avoidance WBRT

Conformal WBRT

Feng-Ming Hsu, MD

Brain metastases are the most common brain tumors in adults. It is estimated that around 10-30% of cancer patients would develop brain metastases during the course of their illness.

Whole brain radiotherapy (WBRT) is the treatment of choice for the majority of patients with brain metastases. WBRT yields high radiologic response rate (27\~56%) and is effective in rapid palliation of neurologic symptoms as well as prolongs time to neurocognitive function decline caused by intracranial lesions. By using conventional fractionation, 33% of patients developed late neurocognitive toxicity while memory impairment was the most common symptom. The incidence is even higher when a formal and sensitive neurocognitive assessment was prospectively evaluated. With more long-term survivors nowadays, it has become increasingly important to minimize neurocognitive function decline and maintain quality of life in patients with brain metastasis.

The function of hippocampus is cooperation in learning, consolidation and retrieval of information and essential for formation of new memories. Bilateral and unilateral radiation injury of the hippocampus is known to alter learning and memory formation. Several preclinical studies support the hypothesis of hippocampus-mediated cognitive dysfunction by ionizing radiation. Clinical studies show increase in radiation dose to hippocampus is associated with subsequent neurocognitive function impairment in adult and pediatric patients. Furthermore, the preliminary result of Radiation Therapy Oncology Group (RTOG) 0933 suggested hippocampal avoidance significant reduce the mean relative decline at 4 months from 30% in historical cohort with WBRT to 7% in experimental cohort.

Previous studies showed brain structures other than hippocampus are also associated with radiation-induced decline in neurocognitive function. There is presence of placebo effect for interventions seeking improvement in neurocognitive function. In present study, a single blind randomized phase II trial is designed to investigate the effectiveness of neurocognitive function preservation using conformal WBRT with or without hippocampal avoidance.

This is a single institutional, randomized phase II study to assess the neurocognitive outcome of conformal WBRT with or without hippocampal avoidance in patients with multiple brain metastases.

Patients will be randomly assigned 1:1 to receive conformal WBRT with or without hippocampal avoidance using permuted blocks within strata that are defined by Graded Prognostic Assessment (GPA) score and baseline neurocognitive status. All patients and co-investigators except the principal investigator and attending radiation oncologists will be blinded for treatment groups.

The whole brain planning target volume (PTV) will receive 30 Gy in 10 fractions. Treatment will be delivered once daily, 5 fractions per week, over 2 to 2.5 weeks. Breaks in treatment should be minimized.

Hippocampal Avoidance WBRT:

The dose is prescribed such as 90% of cranial content PTV is covered by the prescription dose.

Maximum dose to 2% of the PTV (D2%) is 37.5 Gy, and minimum dose to 98% of the PTV (D98%) is 25 Gy. Minimum dose to 100% of the hippocampal avoidance regions is 10 Gy, and dose to any point within the hippocampal avoidance regions cannot exceed 17 Gy.

Conformal WBRT:

The dose is prescribed such as 95% of cranial content PTV is covered by the prescription dose.

Maximum dose to 1% of the PTV (D1%) is 36 Gy, and minimum dose to 99% of the PTV (D99%) is 27 Gy.

Follow-up \& Assessment

Side effect evaluation:

* Acute (≤ 90 days from WBRT start) toxicities (CTCAE ver.4)
* Late (\> 90 days from WBRT start) toxicities (CTCAE ver.4)

Functional evaluation: at baseline, 2-, 4- ,and 6-month, every 3 months for 12 months until intracranial disease progression or death after WBRT

* Neurocognitive function
* Self-reported cognitive functioning (two items from EORTC Quality of Life Questionnaire-C30 Taiwan)
* Health-related quality of life specific for brain neoplasms (EORTC Quality of Life Questionnaire-Brain Neoplasm Taiwan)

Efficacy evaluation:

* Follow-up brain MRI at 4-, 9- ,and 12-month until intracranial disease progression, or death.
* Overall survival

Neurocognitive Outcome of Conformal WBRT w/wo Hippocampal Avoidance for Brain Metastases

Neurocognitive Outcome of Conformal Whole Brain Radiotherapy With or Without Hippocampal Avoidance for Brain Metastases: A Phase II Single Blind Randomized Trial

Number of participants with Genomic risk of neurocognitive impairment after WBRT

Decline in Hopkins Verbal Learning Test-Revised (HVTL-R) delayed recall score from baseline to 4 months after the start of conformal whole brain radiotherapy with or without hippocampal avoidance for brain metastases

Evaluate neurocognitive function by a standardized neurocognitive battery (HVTL-R, Trail Making Test Part A \& B, forward \& backward Digit Span).

EORTC Quality of Life-Core 30 questionnaire module and Quality of Life questionnaire -brain

Common Toxicity Criteria for Adverse Events version 4

Number of participant with intracranial progression on MRI of brain

Spots Global Cancer Trial Database for hippocampal avoidance wbrt