Metastatic Tumors

Brain metastases occur in 10-30% of patients with cancer. They are by far the most common type of brain tumor, with well over 100,000 new cases diagnosed in the United States each year. The use of magnetic resonance imaging (MRI) has significantly improved the ability to detect small brain metastases, and has increased the number of patients diagnosed with this condition as well.

Treatment has traditionally consisted of whole brain radiation therapy when multiple metastases are present. This treatment frequently improves patients' symptoms, but tumor recurrence in the brain after radiotherapy is common. Certain types of malignancies tend to respond better to whole brain radiotherapy, while certain cancers (sarcomas, renal cell carcinoma and melanoma), tend to be poorly responsive (radioresistant) to conventional radiation therapy.

When only a single brain metastasis is present, surgical removal plus radiation therapy has been shown to improve survival compared to conventional radiation therapy alone. Surgery is also useful for patients with large tumors that cause compression of surrounding brain; rapid decompression can be achieved quickly with surgical removal. However, when multiple metastases are present or when patients have active disease elsewhere in the body, surgery is not usually recommended.

Radiosurgery has been used extensively for patients with brain metastases with excellent results. Tumor control rates (no evidence of further growth) after radiosurgery are approximately 80-90%. Patients with radioresistant brain metastases (melanoma, renal cell carcinoma and sarcoma) treated with radiosurgery have high tumor control rates as well.

Survival rates after radiosurgery are equivalent to surgery and radiation therapy for patients with a solitary brain metastasis. Additionally, selected patients with multiple metastases and patients with coexisting medical problems who are not surgical candidates can be treated with radiosurgery. Complication rates from radiosurgery are low, typically in the range of 5%.

Radiosurgery avoids many of the problems associated with surgery in this group of patients. No surgical incision is necessary, no general anesthesia is required, patient discomfort is minimal, no prolonged periods for hospitalization and patient recovery are necessary, and many of the risks of surgery (e.g. infection, hemorrhage, deep vein thrombosis, operative mortality) are avoided. Additionally, tumors in surgically inaccessible areas can be successfully treated.

The Perfexion Gamma Knife allows rapid treatment of multiple metastatic tumors in the brain, making it possible to frequently avoid whole brain radiation.

References
Suh J: Results of Patients with Newly Diagnosed Single Brain Metastasis Treated with Stereotactic Radiosurgery with or without Whole Brain Radiation Therapy. in Radiosurgery. Basel, Karger, 1998, vol 2, pp 51-63

Flickenger J et al: Radiosurgery Management of Brain Metastases from Systemic Cancer. in Gamma Knife Brain Surgery. Prog Neurol Surg. Basel, Karger, 1998, vol 14, pp 114-127