A gene-activity test conducted by the National Cancer Institute identified a group of early-stage breast cancer patients who did not greatly benefit from chemo, The Associated Press reports. The study explained that these types of women could skip chemotherapy without affecting their odds of beating the disease. It showed that they are so likely to respond to hormone-blocking drugs and chemo would only expose them to side effects and health risks.

The women who did not use the chemo wound up having less than a 1 percent chance of returning cancer within the next five years, the test found.

“There is really no chance that chemotherapy could make that number better. Using the gene test lets us focus our chemotherapy more on higher risk patients who do benefit,” said Dr. Clifford Hudis of New York’s Memorial Sloan Kettering Cancer Center.

In the United States, more than 100,000 women are diagnosed with early stage, hormone-positive breast cancer. This means that the tumor’s growth is triggered by estrogen or progesterone, which is the most common type of breast cancer, and is separate from tumors that are influenced by Herceptin.

Deciding who can safely skip it is tough because chemo helps kill any stray cancer cell that maybe floating in other areas of the body. This secondary option consists of surgery and years of taking a hormone-blocking drug.

Past studies have attempted to calculate the activity of women’s genes that control cell growth. Based on their numbers they can be categorized as low, intermediate or high risk. Genomic Health Inc., a California company, has created a test called Oncotype DX to measure the growth and a response to the treatment. 10,253 women were tested on and 16 percent were classified as low risk, 67 percent as intermediate risk, and 17 percent as high risk. The study is still continuing but individuals that fell in the intermediate category were randomly selected to be treated with chemo or hormone therapy.

Results for the low risk patients were released after being given the hormone therapy and about 99 percent had not relapsed, 98 percent were alive, and 94 percent were free of invasive cancer.

Patients all over the world have advocated for skipping chemo and trying other methods of testing. Medicare and many insurance companies cover the $4,175 test.

Study leader, Dr. Joseph Sparano of Montefiore Medical Center commented, “You can’t do better than that.”