Your cancer team may recommend treatments other than surgery, such as chemotherapy, radiation therapy or a combination of both, to treat your metastatic brain tumors.
Chemotherapy
This treatment may be used to treat brain metastases, but is more known for treating malignant or higher-grade tumors that originate in the brain. Chemotherapy drugs are used in an attempt to prevent tumor cells from reproducing (cytostatic) or to kill the tumor cells (cytotoxic).
Chemotherapy drugs can be introduced into the body through an artery, vein, muscle, the skin or taken by mouth (systemic delivery) or can be delivered closer to the tumor site to avoid the drugs traveling throughout the body (local delivery).
Although chemotherapy can work well in other parts of the body, many common chemotherapy drugs are not able to cross the blood-brain barrier in concentrations high enough to have a significant impact on brain metastases [1]. The blood brain barrier is the protective roadblock that prevents certain substances in the blood from reaching the brain. Chemotherapy drugs are filtered out, too, preventing them from effectively killing brain cancer cells. Some brain cancer cells, however, are much more sensitive to chemotherapy than others and therefore respond better to the drugs that do manage to pass through. This has been seen with brain metastases from germinomas and certain types of breast cancer [2].
In general, 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 [2]. Treatment of brain metastases, therefore, usually focuses on surgery—also called resection, radiosurgery and radiation therapy.
Radiation Therapy (RT)
Radiotherapy (RT)—This is a common cancer treatment for brain tumors. High doses of radiation are aimed at the tumor to eliminate the tumor or stop or slow its growth. Radiation can be used alone or in addition to surgery or chemotherapy.
Stereotactic Radiosurgery (SRS)—Another form of radiation therapy, stereotactic radiosurgery (SRS) is often called ‘knifeless’ surgery due to the ability to precisely target cancer cells while sparing healthy surrounding brain tissue.
SRS can be delivered in two ways:
Whole Brain Radiation Therapy (WBRT)—the conventional radiation therapy method for brain metastases, whole brain radiotherapy, has been in use since 1954 [3,4] even though there is a risk of short and long term side effects [5] [6]. WBRT is just what it sounds like—giving radiation to the entire brain, even to healthy tissue.
Proton Therapy—This treatment uses a system called a cyclotron to speed up and direct protons at a tumor using beam-shaping blocks, which match the shape of the tumor.
Particle Therapy—Similar to proton therapy but larger, heavier particles are used to treat the cancer cells.
Alternative and Integrative Medicine—Some people choose to treat the illness or source of the disease instead of using conventional treatments. These alternative therapies may help to heal the body.
See Understand Radiation Therapy for Brain Metastases for a more in-depth discussion of the treatment technologies.
[1] Eichler, A. F. et al. The biology of brain metastases-translation to new therapies. Nat. Rev. Clin. Oncol. 8, 344–56 (2011).
[2] 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).
[3] Chao, J. H., Phillips, R. & Nickson, J. J. Roentgen-ray therapy of cerebral metastases. Cancer 7, 682–9 (1954).
[4] Chu, F. C. H. & Hilaris, B. B. Value of radiation therapy in the management of intracranial metastases. Cancer 14, 577–581 (1961).
[5] Metz, J., Smith, D., Mick, R. & Lustig, R. A phase I study of topical Tempol for the prevention of alopecia induced by whole brain radiotherapy. Clin. cancer Res. 10, 6411–6417 (2004).
[6] Barani, I. J., Larson, D. a & Berger, M. S. Future directions in treatment of brain metastases. Surg. Neurol. Int. 4, S220–30 (2013).
