The Grapevine

Most Women With Breast Cancer Don't Need Chemotherapy, Study Finds

For many years, a genomic test helped patients with a common form of breast cancer in determining whether they need chemotherapy. Due to the scoring system of the test, many women still faced uncertainty. But according to new research, nearly 70 percent of women diagnosed with the early-stage invasive breast cancer could forgo chemotherapy safely.

The study "Adjuvant Chemotherapy Guided by a 21-Gene Expression Assay in Breast Cancer" was published in the New England Journal of Medicine on June 3.

"Half of all breast cancers are hormone receptor-positive, HER2-negative, and axillary node-negative," said lead author Dr. Joseph A. Sparano, associate director for clinical research at the Albert Einstein Cancer Center, New York. Researchers focused on this form of cancer for the study and also used genetic testing to find out which patients were more likely to have recurrent cancer.

Oncotype DX is a test which examines tumor tissue and measures the expression of 21 genes to predict risk on a scale of 0 to 100. Chemotherapy is said to be of benefit when the score is between 26 and 100. Meanwhile, when the recurrence score is low at anywhere between 0 and 10, it predicts a very low rate of distant recurrence (2 percent) at 10 years which may not be affected by chemotherapy.

Until now, women falling in the gray area were faced with a tough choice on whether or not to opt for chemotherapy. Researchers designed the Trial Assigning Individualized Options for Treatment (TAILORx), a clinical trial that followed over 10,000 women diagnosed with breast cancer between 2006 and 2010.

The results showed those with scores between 11 and 25 had a similar rate of cancer-free survival, regardless of whether they opted for chemotherapy.

The rate was 93.9 percent for those who received only hormone therapy and 93.8 percent for those who received hormone therapy combined with chemotherapy. However, patients under the age of 50 with scores between 21 and 25 still experienced some benefit from chemotherapy.

"These data confirm that using a 21-gene expression test to assess the risk of cancer recurrence can spare women unnecessary treatment if the test indicates that chemotherapy is not likely to provide benefit," said Sparano.

Sparano estimates 135,000 new cases of this form of breast cancer occurring on an annual basis in the United States. Among the 100,000 who would qualify for the test, almost two-thirds (70 percent) fall into the 11-25 range and can use these findings to make a more informed decision. 

"This information really addresses a major unmet medical need to have a very high level of evidence to make potentially life-saving decisions," he added. "This has very important public health implications. It helps direct patients to the right therapy so that we're treating the right people with the right therapy at the right time."

The research was also presented as a plenary session at the 2018 annual meeting of the American Society of Clinical Oncology in Chicago.