Treatment for Brain Metastasis

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The Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 8 de mayo del 2013

Question

My brother is 43 years old and had a non-small cell tumor removed from his lung. There was no follow-up treatment because they "got it all." Six months later, he was found to have a tumor in the brain that was thought to have spread there from his lung cancer. When he had a "stroke," they removed the tumor from the brain surgically. They now are recommending Gamma Knife to that site. However, pre-radiation tests show recurrence of cancer in lung. Our question is given the poor prognosis, and his wish to avoid pain, should he have the Gamma Knife to the brain site? Should he have surgery on the new lung tumor? Should he have follow-up treatment for the lung with chemotherapy and/or radiation therapy?

Answer

Mitchell Machtay, MD, Radiation Oncologist, responds:

It is uncertain why lung cancer tends to spread to the brain (metastases), but it is an increasingly common problem. Perhaps the rich supply of blood vessels and nutrients within the brain make it an attractive breeding ground for aggressive cancer cells (the "seed and soil" hypothesis). It is also likely that brain metastases are more obvious to us than they used to be, given improvements in imaging tests (CT and MRI scans). Brain metastases often cause symptoms, which can be mild (forgetfulness, tiredness) or very severe, like a stroke, severe headaches, problems with vision, or seizures. Thus, even though it is extremely unlikely that anyone with brain metastases from lung cancer can be "cured," most oncologists believe it is important to treat this condition, even if there are signs of cancer in other parts of the body. The goal of treatment is to prevent any further tumor growth or spread within the brain, and thus hopefully preserve a reasonably good quality of life. At this time, the only effective treatments against brain metastases are surgery and radiation therapy. Chemotherapy and most of the new "targeted" anti-cancer drugs continue to show promise against cancer in the lung and other parts of the body, but they do not appear to work well in the brain.

There are several different ways to deliver radiation therapy for cancer in the brain. The most common method is to administer a series of 10 to 20 daily radiation treatments to the entire brain. This can treat the known lesions in the brain that are seen on imaging and has been shown to significantly reduce and/or delay the growth and appearance of new areas of brain metastases. However, the radiation dose that can be safely given to the entire brain is modest and often insufficient for long-term eradication of brain metastases. Also, radiation therapy to the entire brain can cause significant side effects, including fatigue, decreased memory ability, and wobbliness. These symptoms are usually not miserable (not as severe as uncontrolled cancer in the brain), but they can last for months to years and sometimes even for the remainder of a person's lifetime. Thus, some patients with extensive brain metastases and very short life expectancy choose not to have radiation therapy in favor of using pain medications and steroids to help ease the symptoms of the disease.

For healthier patients who have a very limited amount of cancer in the brain, there is a great deal of interest in using a type of radiation called "radiosurgery." Radiosurgery can be delivered by a modified Linear Accelerator (Linac-based SRS) or by a specialized radiation machine called a Gamma Knife. Radiosurgery is a complex technique of radiation therapy in which massive doses of radiation are meticulously pinpointed to a small area within the brain (the site of the cancer). Usually, this is sufficient to effectively destroy a small brain tumor, similar to surgical removal. Radiosurgery can have fewer cognitive side effects than whole brain radiation, BUT this must be weighed against the fact that it can only treat a small area (about an inch or less in size) of the brain. Unfortunately, for patients with lung cancer that has spread to the brain, there is a high risk of many other areas in the brain containing cancer, even if nothing else is visible on scans. Thus, for most patients with lung cancer that has spread to the brain, I usually recommend whole brain radiation before or after radiosurgery for otherwise healthy patients. While these treatments do have side effects, they rarely cause any pain or severe discomfort. You should discuss the various radiation therapy options in detail with your radiation oncologist and neurosurgeon or neurologist. I would also recommend getting a new an up-to-date MRI scan of the brain as soon before starting radiation therapy.

The other big problem that you raised is the "recurrence of cancer in the lung." When someone is diagnosed with brain metastases it is important to check (restage) the rest of the body for signs of cancer. This typically includes a CT scan of the chest and abdomen with contrast or a PET/CT scan. After surgery and/or radiation therapy to the lung, it can be very difficult to distinguish recurrence of cancer from other disorders such as post-treatment scarring or infections caused by a lowered immune system. I would recommend obtaining consultations with a medical oncologist (chemotherapy specialist) and pulmonologist (lung specialist) to discuss what to do about the cancer outside of the brain. Your radiation oncologist should also be part of this difficult discussion. However, this process does not have to interfere with your decision regarding treatment to the brain. I can understand the reluctance to go ahead with brain radiation therapy in light of the overall poor long-term prognosis, but sometimes I think it is best to take a huge and terrible mega-problem and divide it into several smaller and hopefully more manageable problems. I sincerely wish you and your brother the best in this difficult time