By Admin at 7 Nov 2016, 15:33 PM

Tumor genome testing is being increasingly used to help women with certain types of breast cancer make important treatment decisions. This includes women with early-stage hormone-positive breast cancer that has not spread to the lymph nodes.

Such cancers are typically treated with surgery and hormone-blocking drugs. Some women also receive chemotherapy to kill any cancer cells that may have spread from the breast to other areas of the body.

Chemotherapy carries risks of its own, however, so it can be challenging to determine which women will benefit from its use and which may be better off without it. This is where precision medicine, including tumor genome testing, shines.

A genetic test known as the 21-gene recurrence score assay (RS) measures the activity of genes that control cell growth and more. A high score on the test indicates a woman has a high risk of cancer recurrence and chemotherapy is recommended. A low score suggests chemotherapy can safely be skipped.

Past research, including one study published in the New England Journal of Medicine, attests to the test’s effectiveness. Women who received low scores on the test received hormone-blocking drugs to treat breast cancer while those with high scores received the drugs and chemotherapy.

Five years later, 99 percent of the women in the low-risk group were alive and had not relapsed. Ninety-four percent of the women were also free of invasive cancer.

A new study, published in the American Cancer Society’s journal Cancer, also confirmed the test’s beneficial use in everyday practice, not just in clinical trials. In a survey of more than 1,500 patients with early-stage breast cancer, nearly all of the women who received a high RS were advised to receive chemotherapy, and most followed the recommendation.

Meanwhile, most of the patients with a low RS were advised against chemotherapy, and few women with low scores ended up receiving chemotherapy treatment.  The results suggest this form of precision medicine is being used as intended by physicians. Study author Christopher Friese, PhD, RN, of the University of Michigan School of Nursing in Ann Arbor, told Medical News Today:

"We found that most doctors were using tumor genomic tests in ways that were recommended by professional guidelines, although we found that some patients were having the test where there is no professional recommendation for the test."

At this point, the test is primarily used for women with early-stage cancer that has not spread to the lymph nodes. It is still being investigated whether tumor genomic testing is beneficial for women with breast cancer that has spread to their lymph nodes.

Sources
Cancer October 24, 2016
Medical News Today October 25, 2016
New England Journal of Medicine September 28, 2015

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