What is the role of radiation therapy in the treatment of brain metastasis?

Updated: Aug 01, 2018
  • Author: Victor Tse, MD, PhD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Radiation therapy has become a mainstream therapy for brain metastasis. Radiation therapy includes WBRT and stereotactic radiosurgery.

For decades, WBRT has been advocated for patients with multiple lesions. WBRT is also advocated for patients with a low Karnofsky score or a life expectancy of < 3 months. Effectiveness of this treatment depends on the histological type of the tumor. Small-cell lung tumor and germ-cell tumors are highly susceptible to radiation, other types of lung cancer and breast cancers are less sensitive, and melanoma and renal-cell carcinoma are not sensitive at all.

Regarding the effectiveness of radiation therapy, the Radiation Therapy Oncology Group (RTOG) has recommended a treatment schedule of 30 Gy delivered in 10 fractions over 2 weeks. With this treatment, median survival is 3-6 months depending on number of lesions, their radiosensitivity, and the status of systemic disease. Disadvantages are short- and long-term adverse effects. Besides hair loss, headache, nausea, otitis media, and cerebral edema, patients may have increased somnolence. After 6 months, patients may have evidence of radiation necrosis, leukoencephalopathy, and/or dementia.

Hippocampal avoidance (HA), a modification of WBRT, may preserve short-term memory in cancer patients with brain metastases. In a study involving 113 adult cancer patients with a measurable brain metastasis outside a 5-mm margin around the hippocampus, the HA-WBRT group showed a 7% performance decline on a standardized memory test at 4 months, whereas the control group showed a 30% decline. [17] At 6 months, the decline averaged 2%.


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