A new study published in the New England Journal of Medicine showed that many women diagnosed with the most common type of breast cancer that has not spread to the lymph nodes – up to 70 percent of them – may be able to forgo chemotherapy without increasing the risk of recurrence. The findings could impact tens of thousands of women annually, sparing them from the unpleasant and even potentially harmful side effects of the therapy.

Elaine Lee Wade, MD, Medical Oncologist specializing in breast cancer at NorthShore, notes that the study was based off a 21-gene test performed on tumors that has been available for breast cancer patients for years, including ones at NorthShore. But the results provide more guidance on how best to treat breast cancer patients, particularly ones where it’s not entirely clear that chemotherapy will provide a benefit.

“This test is not for everyone but has made a tremendous difference in the care of many of our patients, saving them from exposure to chemotherapy on the one hand and helping others to realize that chemotherapy could really make the difference for their future,” said Dr. Wade.

Examining genes from a patient’s breast cancer biopsy sample, the test assigns a patient a “recurrence score” from 0 to 100. The study helps clarify what to do with women whose results fall into the intermediate range, according to Dr. Wade. “The results suggest that certain women can skip chemo and not lose benefit or increase the risk of recurrence.”

But Dr. Wade said no one test is going to determine a course of treatment.

“Caring for patients is always complicated because the data are continuing to evolve with time and experience,” she said. “Each case is unique. Decisions regarding treatment need to incorporate multiple factors including other ailments, age, functional status and more. The information from genomic assays is one piece of many that fits together to make the treatment plan for an individual.”