HF-SRT vs. HS-WBRT in Treating Patients With Brain Oligometastases

\[Background\] For newly-diagnosed patients with brain metastases (BMs), conventional whole-brain radiotherapy (WBRT) might still remain a common palliative management. However, WBRT-related late consequences, particularly a decline in neurocognitive functions (NCFs), are a major concern. Actually, WBRT-related neurocognitive dysfunction is usually characterized as deterioration involving learning and memory, in which the extremely radiosensitive hippocampus indeed plays a critical role. To postpone the occurrence and mitigate neurocognitive impairments associated with conventional WBRT, there have been some strategies in the clinical practice of radiation oncology. Among them, the technology/technique of highly precise/accurate stereotactic radiosurgery or stereotactic radiotherapy (i.e., hypofractionated stereotactic radiotherapy, HS-SRT) might have been widely administered in irradiating exclusively the focal brain metastatic lesions, particularly in cancer patients with a limited number of brain metastases. By contrast, the planning strategy of hippocampus avoidance during the course of whole-brain irradiation has also been well-established in preserving NCFs. \[Methods\] Newly-diagnosed cancer patients harboring 1 - 4 brain metastatic lesions are eligible if they still have fair/good performance status. Eligible and enrolled should receive baseline brain MRI examination and pre-WBRT neurocognitive assessment. Although non-randomized, this phase II trial comprises two prospective (radiotherapeutic) cohorts with individually different planning techniques and prescription schedules. Cohort I represents patients referred for arranging partial-brain irradiation; namely, a course of hypofractionated stereotactic radiotherapy (HF-SRT) is delivered within 2 weeks with a cumulative dose of 3000 - 3500 cGy in 5 fractions. By contrast, Cohort II stands for patients referred for arranging the course of hippocampus-sparing WBRT (HS-WBRT), delivered within 3 weeks with a c