Surgery has proven to be one of the most effective methods for managing brain cancer [1]. Removing a growing brain tumor is important because as the tumor increases in size, it increases the pressure inside the head. This pressure can cause symptoms such as epileptic seizures, vomiting or severe headaches. For the treatment of brain metastases that are so large they cause symptoms, it is generally accepted that surgery is helpful for a single large tumor in an accessible region of the brain. It is not used when there are multiple metastases or if the tumor is located in a surgically inaccessible region (such as the motor cortex, thalamus or brainstem).
Unfortunately, less than half of patients with metastasis to the brain have a single tumor, many of which are deep inside the brain [2]. The remaining patients have many tumors. The general health of the patient (for example, absence of heart disease) also needs to be taken into account when considering surgery. With all factors considered, surgery is applicable only for a small group of patients with tumors so large that they cause symptoms. Different options are available for these patients. Complete removal of the tumor in one piece minimizes the risk of tumor cells spreading along the surgical pathway; however, it is not always possible for the surgeon to remove the whole tumor in one piece. Moreover, this kind of surgery might be more invasive as it requires a larger area to be removed. The chance of the tumor returning is higher if the surgery is not followed up with radiotherapy or radiosurgery.
Combination Therapies for Brain Metastasis
Many cancer care teams treat patients with a combination of therapies, sometimes called polytherapy. These treatments may be prescribed one after another, or sometimes, concurrently, meaning at the same time. In some cancers, the dual treatments can make a great difference in eliminating a tumor, controlling growth of a tumor, and preventing or controlling cancer that has spread to another part of the body.
Whole brain radiation therapy (WBRT) after surgery is still a common treatment for multiple brain metastases after surgery but is associated with challenges such as known risk of a decline in mental function [3].
Depending on the size of the tumor, focused stereotactic radiosurgery can be delivered either prior to surgery (typically two to three days before) or after. After surgery, radiation is normally used to target the tumor cavity and the surgery pathway, which reduces the likelihood of metastasis re-growing in those areas. Irradiating the tumor before surgery simplifies treatment planning since the boundary between tumor and healthy tissue becomes clearer [4]. Radiosurgery before surgery also reduces the area that must be treated, since no surgical pathway has been created yet.
Some chemotherapy agents are promising for the management of brain mets, but the data is still unclear about whether this is an effective and safe alternative [5]. Treatment of brain metastases, therefore, usually focuses on surgery, radiosurgery, and radiation therapy.
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[1] Patchell, R. a. The management of brain metastases. Cancer Treat. Rev. 29, 533–540 (2003).
[2] Delattre, J. Y., Krol, G., Thaler, H. T. & Posner, J. B. Distribution of brain metastases. Arch. Neurol. 45, 741–4 (1988).
[3] Onodera, S. et al. The value of 4-month neurocognitive function as an endpoint in brain metastases trials. J. Neurooncol. 120, 311–9 (2014).
[4] Asher, A. L. et al. A New Treatment Paradigm: Neoadjuvant Radiosurgery Before Surgical Resection of Brain Metastases With Analysis of Local Tumor Recurrence. Int. J. Radiat. Oncol. 88, 899–906 (2014).
[5] Mehta, M. P. et al. The role of chemotherapy in the management of newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline. J. Neurooncol. 96, 71–83 (2010).
