Roughly 70% of women with the commonest type of early breast cancer can skip chemotherapy. That was the headline from the TAILORx trial, unveiled at the ASCO yearly meeting (June 3, 2018) with simultaneous publication in a leading medical journal, and it rests on a single lab test, Oncotype DX.
The test reads the activity of 21 genes in a sample of the tumor. Doctors use it to estimate two things for women with early-stage, estrogen-receptor-positive, HER2-negative cancer: how likely the disease is to come back, and how much chemotherapy after surgery would help. Results come as a Recurrence Score between 0 and 100. Genomic Health developed the assay, and it now belongs to Exact Sciences.
What TAILORx found
The trial enrolled 10,273 women whose cancer had not reached the lymph nodes. Everyone’s tumor was tested. For the 6,711 women (69%) with a mid-range score of 11 to 25, researchers drew lots: 3,312 got chemotherapy plus hormonal therapy, 3,399 got hormonal therapy alone.
Half were followed for more than 8.5 years. By then the two arms looked almost alike. Invasive disease-free survival was 83.3% with hormonal therapy alone and 84.3% with chemotherapy added.
“With results of this groundbreaking study, we now can safely avoid chemotherapy in about 70% of patients who are diagnosed with the most common form of breast cancer,” said Kathy Albain of Loyola University, one of the authors. Lead author Joseph A. Sparano of the Albert Einstein Cancer Center estimated the findings would apply to about 60,000 women a year in the United States.
There was a catch. Women aged 50 or younger with a score of 16 to 25 seemed to have fewer distant recurrences when chemotherapy was added. So the safe-to-skip group was defined narrowly: scores of 0 to 10, women over 50 scoring 11 to 25, and women 50 or younger scoring 11 to 15.
The money question
Skipping unnecessary chemotherapy also shifts costs. A cost-consequence model built for the Netherlands compared Oncotype DX with no genomic testing and with a rival test, MammaPrint, in node-positive disease. Total costs were lowest with Oncotype DX, because fewer patients ended up on adjuvant chemotherapy.
In February 2026 Exact Sciences announced that more than two million patients worldwide had used the test, and estimated that 1.6 million of them avoided unnecessary treatment. Using a published economic model, the company put average lifetime savings at about $10,000 for each patient in the US health system. That figure is a company estimate, not an independent audit.
The test carries a Category 1A recommendation in the National Comprehensive Cancer Network guidelines, and Exact Sciences says it is used in more than 100 countries.
Sources
- TAILORx Results Suggest About 70% of Women With Early-Stage, Hormone-Receptor-Positive, HER2-Negative Disease Can Skip Chemotherapy | Breastcancer.org
- A cost-consequence model of using the 21-gene assay to identify patients with early-stage node-positive breast cancer who benefit from adjuvant chemotherapy in the Netherlands | PubMed
- Oncotype DX Breast Recurrence Score Test Surpasses 2 Million Patients Worldwide | Exact Sciences via Nasdaq
