NEW YORKBrain metastases are like orphans when it comes to medical specialties. They really do not belong to any particular area, said Raymond Sawaya, MD, professor and chair of neurosurgery, M.D. Anderson Cancer Center. But evaluation and treatment are improving, he told patients taking part in a teleconference sponsored by the National Brain Tumor Foundation, Cancer Care, Inc., and the Oncology Nursing Society.
Brain metastases are the most common form of brain tumors, Dr. Sawaya said. In the United States, it is estimated that more than 100,000 new cases of brain metastases are diagnosed each year. The number of gliomas diagnosed annually is approximately 20,000.
Lung cancer is the most common cause of brain metastases, not only because of the diseases propensity to travel to the brain but also because it is the most common form of cancer, Dr. Sawaya said. After lung cancer, the most common causes are breast cancer, melanoma, renal cell cancer, and colon cancer.
Although only about 2% to 5% of colon cancer patients develop brain metastases, it accounts for a relatively large number of brain metastases patients because it is such a common cancer.
The prognosis of patients with brain metastases can also differ according to the origin of the cancer. If you look at 100 patients with lung cancer, their 2-year survival is about 28%, Dr. Sawaya said. In colon cancer, it is 0%. So it gives you an idea that no matter how effective we might be in treating the brain cancer, patients do die and frequently. The cause of death is most frequently related to the systemic cancer.
Although CT scans are commonly used to check for brain metastases, MRI scans, because of their greater resolution and sensitivity, are much better, he said. Unless you do an MRI scan, you are not going to be able to detect multiple metastases, and thats a major factor because patient survival and choice of treatments depend on knowing the number of metastases.
Presenting symptoms are the same whether caused by a primary brain tumor or metastases: seizure or headache caused by increased intracranial pressure, or some form of neurologic deficit, with weakness or speech difficulty the most common.
Many patients may be asymptomatic. However, small lesions that do not cause symptoms are increasingly being detected by oncologists who are ordering a CT scan or MRI for patients with cancers known to have a tendency to metastasize to the brain.
In the initial phase of treatment, steroids are used to reduce symptoms due to brain edema, Dr. Sawaya said. Anti-convulsants are not routinely prescribed, since a large number of brain metastases patients do not have seizures. When anticonvulsants are used, they are usually prescribed after surgery, although some physicians will choose to give them only to those postoperative patients who have had seizures.
Among patents with only one metastasis, complete removal by surgery plus whole brain radiation therapy is the gold standard, Dr. Sawaya said. These patients will do much better in terms of survival and quality of life, compared to those who get radiation therapy alone without surgery.
Multiple Brain Tumors
Whole brain radiation alone is very valuable in most patients who have multiple brain tumors that cannot be treated otherwise. The dilemma remains the neuropsychologic and cognitive effects of radiation. Even given in 10 to 15 fractions, the amount of radiation administered affects the brain, especially if the patient is age 65 or over.
When patients live more than 6 months, the cognitive deficits that result become more obvious. They do not have to be severe to affect the patient, Dr. Sawaya explained.
The problem is we cannot predict accurately whether a patient will live 6 months or not. Even if they have disseminated cancer, they may respond very well to chemotherapy, he said. Therefore, at this point, it is recommended that a person with a single brain metastasis who can undergo surgery, have surgery and, after that, whole brain radiation.
Patient who are not expected to survive that long may very well benefit from radiation alone and avoid being subjected to surgery, Dr. Sawaya said.
As yet, there have been no randomized studies comparing radiosurgery with surgery. But there have been clinical observations that radiosurgery is not effective for large tumors, 3 cm or larger, Dr. Sawaya said. When we are dealing with small metastases like those that may be
2 cm in diameter or less, there might be a role for radiosurgery, and it might even replace surgery, but I would present that as a current area of intense study and controversy, he said.
Although chemotherapy has not played a significant role in the management of brain metastases, Dr. Sawaya said, there are some data showing that a percentage of breast cancer patients with brain metastases do respond to chemotherapy, and protocols are needed to explore this area.