Most Women with Early-Stage Breast Cancer Don’t Need Chemotherapy

A much anticipated study comparing the long-term survival of women with early-stage breast cancer who received chemotherapy with women who did not has just been released. The results, reported in the New England Journal of Medicine on June 3, 2018, will likely spare about 60,000 women in the United States each year from treatment with chemotherapy, according to the New York Times.

Many breast cancer patients will now be spared the toxic effects of chemotherapy
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The study, named TAILORx, followed nearly 10,000 women aged 18 to 75 who had a diagnosis of early-stage breast cancer that had not spread to the lymph nodes or beyond. Its purpose was to determine if a gene assay test could identify women whose tumors could be successfully treated with endocrine therapy alone without the addition of chemotherapy. After an average of nine years of follow-up, the researchers determined that about 70 percent of women with early-stage breast cancer who are currently treated with chemotherapy would survive just as long with endocrine therapy alone.

“This is very powerful,” said Dr. Ingrid Mayer, one of the study authors. “It really changes the standard of care.”

Genetic Markers Are the Key

Doctors have long known that chemotherapy may not be necessary for many women with early-stage breast cancer. But until recently, they did not know, except in rare cases, which patients would benefit and which patients would not. Thus, they followed the National Cancer Institute guidelines, issued in 2000, which said that chemotherapy for all breast cancers was the best way to prevent recurrences and save lives.

Then, in 2004, a test became available that could identify genetic markers that were a reliable indicator of whether or not a woman’s breast cancer would recur. (Recurrent tumors are typically more aggressive and much harder to treat.) Doctors perform the test, called Oncotype DX Breast Cancer Assay, on samples taken from a tumor after it is surgically removed. Test results are reported as “recurrence scores” on a 0 to 100 scale.

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Over time, data showed that women whose test score was less than 10 had a very low incidence of recurrence and did not need chemotherapy. Women whose scores were 25 or greater did.

But that left a huge gray area, and a significant one. Most women who got the test scored between 11 and 25. And doctors still had no idea whether these women would benefit from the addition of chemotherapy or would fare just as well on endocrine therapy alone. So chemotherapy for almost all early-stage breast cancers remained the standard of care.

An Important Question Answered

Then, in 2006, researchers from Canada and the United States teamed up to gather evidence as to whether women in the group that scored 11 to 25 on the gene assay test actually benefited from chemotherapy. They recruited over 10,000 breast cancer patients from cancer centers throughout North America who met the criteria for the study: early stage breast cancer that had not spread; a tumor that was sensitive to estrogen; no evidence of a protein known as HER2; and a recurrence score between 11 and 25. They randomized the women to two separate groups. One group received endocrine therapy alone, and one group received endocrine therapy plus one of two chemotherapy treatment protocols. Then they followed the women for 9 years.

The results were unequivocal. Women who received chemotherapy had no fewer recurrences, either at five years or nine years, and lived no longer than those who did not. The average survival rate of both groups after nine years was virtually identical (93.8 and 93.9 percent). The only outliers were a small percentage of women who were diagnosed with breast cancer when they were under 50 years of age and had recurrence scores between 16 and 25. For some reason that the researchers haven’t yet determined, these women had a slightly increased risk of recurrence despite their assay scores.

A Game Changer

The TAILORx study will undoubtedly be a game changer in the oncology community for physicians and patients alike. Oncologists will no longer have to wonder about whether to recommend chemotherapy to a vast majority of their breast cancer patients. And hundreds of thousands of women will be spared chemotherapy’s toxic effects, including long-term complications such as osteoporosis, chronic nerve pain, heart damage and a higher risk of leukemia later in life.

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“I’ll be able to look people in the eye and say, ‘We analyzed your tumor, you have a really good prognosis and you actually don’t need chemotherapy,’ said Dr. Larry Norton, Medical Director of the Evelyn H. Lauder Breast Center at Memorial Sloan Kettering Cancer Center in New York. “That’s a nice thing to be able to say to somebody,” he added.  

And it will certainly be a nice thing  for women facing a breast cancer diagnosis to hear.