Neurocognitive Outcomes In Patients Treated With Radiotherapy For Five Or More Brain Metastases

This is randomized controlled study of neurocognitive outcomes in patients with five or more brain metastases treated with stereotactic radiosurgery (SRS), specifically the Gamma Knife (GK) system, or whole-brain radiation therapy (WBRT). The goal of the study is to enroll 120 patients with at least five (≥5) newly-diagnosed brain metastases from non-melanoma, except melanoma patients with BRAF V600E B-Raf protein mutation, primary cancers with the largest intracranial tumor volume ≤10 cc, ≤15 cc total tumor volume, absence of leptomeningeal disease on MRI, and Karnofsky performance status (KPS) score ≥70 (unless due to intracranial disease), and KPS expected to improve to ≥70 with treatment.

All study participants will undergo standard, pre-treatment clinical evaluations that include: complete clinical/neurologic exam, performance status assessment, systemic staging, and diagnostic MRI of the brain. The baseline neurocognitive function (NCF) will be assessed by a short (20-30 minute) online test battery that can be completed by patients at home. All study participants will be randomized to receive radiosurgical or whole-brain radiation treatment for their brain metastases. All patients will have treatment response assessments every 10-12 weeks consisting of a clinical/neurologic exam, performance status evaluation, disease re-staging (if indicated), and diagnostic MRI of the brain. If progressive disease is identified (radiographic progression of treated lesions or new brain lesions), the patients will be considered for "salvage" therapy which will primarily consist of SRS, WBRT, surgery±brachytherapy or best supportive care (e.g. steroids only). The preferred salvage therapy will be SRS provided that the re-treatment criteria are met. The NCF follow-up will start 2 weeks after completion of the initial SRS treatment and will repeat at 2-week intervals, irrespective of any salvage therapy that may be indicated. All study participants will be followed until death or withdrawal from the study.

The primary aim of this study is to compare the change in neurocognitive outcome between baseline and 6 months for surviving patients in upfront WBRT versus SRS treatment groups. The primary study endpoint is neurocognitive function as measured by a significant change in online neurocognitive function (oNCF) z-score from baseline to 6 months. The outcomes will be compared after initial treatment and then repeatedly in follow-up, and will include the impact of salvage SRS treatments. This approach will allow us to assess the relative impact on neurocognitive outcomes of repeat SRS treatments to sites of new brain metastases.

Since SRS and WBRT are two very different forms of treatment (single high-dose treatment vs. multiple low-dose treatments) with markedly different target volumes, it is expected that local control rates will also be markedly different. This, in turn, will impact salvage therapies and associated costs. This study will evaluate local control rates and overall intracranial disease control at 3, 6, 9, and 12 months as a function of initial treatment cohort (SRS vs. WBRT). We also expect significant differences between the treatment groups in patient and caregiver reported quality of life (QoL) measures.

It is also expected that the SRS cohort will require multiple SRS treatments over the course of the study since, unlike WBRT, the treatments target only gross brain metastases and do not address microscopic (clinically undetectable) disease. Conversely, WBRT is expected to result in inferior control rates of gross metastatic disease, increasing the likelihood of subsequent SRS or other salvage therapy. For these reasons, we will track the actual costs of treatments over the course of the study, including the need for supportive care and the ability of patients to continue to work in their previous occupation.

The structure of the current study provides a unique opportunity to explore various dosimetric SRS parameters in the setting of multiple brain metastases. Dose-volume criteria for SRS have been established in a prospective RTOG 90-05 dose-finding study and subsequently validated in RTOG 95-08, a randomized controlled trial of WBRT±SRS in patients with 1-3 brain metastases. Several single-institution series as well as multi-institutional retrospective analyses support the use of single-dose SRS for treatment of brain metastases; however, the dose-volume criteria and prescription guidelines are not known in the setting of ≥5 brain metastases where dose interaction among different lesion targets are much more likely. These interactions can potentially lead to increased rates of radiation necrosis, and if the SRS doses are arbitrarily reduced because of such concerns, then to a potentially decreased local control rates. These parameters will be closely tracked in this study with the aim of establishing an evidence-based dosimetric guidelines for radiosurgical treatment of multiple (≥5) brain metastases.

The data gained from this study could help define patient selection and treatment criteria for SRS of multiple brain metastases as a potential alternative to WBRT in a select group of patients. This will also be a first study of its kind to use online neurocognitive assessments for its primary endpoints to demonstrate feasibility and cost-effectiveness of such an approach in a multi-institutional setting.