Prophylactic Brain Radiation Therapy Doesn’t Seem to Cause Cognitive Problems

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Metastatic breast cancer is cancer that has spread to parts of the body away from the breast. The bones, brain, and liver are common places for metastatic breast cancer to spread. Radiation therapy to the brain is one treatment choice doctors may recommend to women who've been diagnosed with breast cancer that has spread to the brain.

Some doctors believe that giving radiation therapy to the brain preventively (prophylactic cranial radiation) can benefit some women diagnosed with metastatic breast cancer that HASN'T spread to the brain. Prophylactic cranial radiation is given to prevent or delay the spread of cancer to the brain.

Still, many doctors are concerned that prophylactic cranial radiation may cause difficulty remembering, thinking, and concentrating -- known as cognitive problems or cognitive dysfunction. Because of these possible side effects, some doctors don't think prophylactic cranial radiation is a good treatment option.

A very small, very early study found that women diagnosed with HER2-positive metastatic breast cancer that hadn't spread to the brain who got prophylactic cranial radiation in addition to Herceptin (chemical name: trastuzumab) and chemotherapy didn't have any more or different cognitive problems than women who got only Herceptin and chemotherapy. These results were presented at the 2010 San Antonio Breast Cancer Symposium (SABCS).

HER2-positive cancers have too many copies of the HER2/neu gene, which make too much of the HER2 protein. HER2-positive breast cancers tend to be aggressive. About 30% to 35% of women diagnosed with metastatic HER2-positive breast cancer eventually will have the cancer spread to the brain. Breast cancer in the brain can cause a number of nervous system problems, including cognitive problems. So women with breast cancer lesions in the brain (brain metastases) usually are advised to avoid complex tasks that could be dangerous, such as driving. Treatment that delays or prevents brain metastases from developing might offer a much better quality of life for women diagnosed with metastatic breast cancer.

The targeted therapies Herceptin and Tykerb (chemical name lapatinib) work against HER2-positive breast cancers by blocking the cancer cells' ability to receive growth signals. Both medicines are approved by the U.S. Food and Drug Administration (FDA) to treat HER2-positive metastatic breast cancer. Herceptin is given intravenously. Tykerb is a pill taken by mouth. Doctors think that treating women with HER2-positive metastatic breast cancer that hasn't spread to the brain with Herceptin and chemotherapy may delay or prevent brain metastases.

In this small, early study, 30 women diagnosed with metastatic HER2-positive breast cancer that had spread to other parts of the body beyond the breast, but not the brain, were treated with Herceptin and chemotherapy. Thirteen women also got prophylactic cranial radiation.

At the study's beginning and then at 3, 6, and 9 months into treatment, the women took a number of tests to figure out if there were any differences in cognitive function, emotional state, and quality of life between the women who got prophylactic cranial radiation and the women who didn't. There were no differences.

This study wasn't designed to prove that prophylactic cranial radiation offered more protection from brain metastases than not having it, so there aren't any firm conclusions. Still, the results do suggest that in some women prophylactic cranial radiation may offer more protection from brain metastases than Herceptin and chemotherapy alone.

Seven of the 17 women (41%) who didn't get prophylactic cranial radiation developed brain metastases during the study compared to only 3 of the 13 women (23%) who got prophylactic cranial radiation.

After 2 years, the overall survival rates were the same in both groups of women.

More research looking at more women is needed to help identify all the benefits and risks of prophylactic cranial radiation. Still, these results suggest that some doctors may be overly concerned about the risks of cognitive problems caused by prophylactic cranial radiation. Based on these results, the researchers feel that concern about cognitive problems shouldn't discourage women diagnosed with metastatic breast cancer from participating in clinical trials on prophylactic cranial radiation.

If you've been diagnosed with metastatic breast cancer that hasn't spread to the brain, you might want to talk to your doctor about this study and ask if prophylactic cranial radiation might have benefits for you. Participating in a clinical trial may be one way to be considered for prophylactic cranial radiation. Ask your doctor about clinical trials that might be a good fit for you and your unique situation. Visit the Breastcancer.org Clinical Trials pages for more information.

You can learn about how radiation therapy is used to treat metastatic breast cancer on the Radiation for Metastatic Breast Cancer page.

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