Earlier this month, news of a groundbreaking study spread like wildfire. The findings are expected to dramatically and quickly change the medical treatment of early-stage breast cancer, sparing tens of thousands of women each year from chemotherapy.
The international study found that many women with early-stage breast cancer who would receive chemotherapy under current standards don’t actually need it.
“This is very powerful. It really changes the standard of care,” Dr. Ingrid A. Mayer, an author of the study from Vanderbilt University Medical Center, told The New York Times.
Gene tests on tumor samples were able to identify women who could forgo chemotherapy in favor of a drug that blocks estrogen or stops the body from making it. The hormone-blocking drug tamoxifen and related medicines, called endocrine therapy, are increasingly factoring into breast cancer treatment because they lower the risks of recurrence, new breast tumors, and death from the disease.
The findings apply to about 60,000 women a year in the United States, according to The Times.
“The results indicate that now we can spare chemotherapy in about 70 percent of patients who would be potential candidates for it based on clinical features,” Dr. Joseph A. Sparano, the leader of the study, told The Times.
Dr. Sparano and Dr. Mayer did caution, however, that some women 50 and younger could benefit from chemotherapy even if the gene-test results suggested otherwise, though it’s not clear why.
The study, called TAILORx, began in 2006 and was paid for by the United States and Canadian governments and philanthropic groups. Genomic Health, the company that makes the gene test, helped pay after 2016, according to The Times. TAILORx is part of a larger effort to fine-tune cancer treatments and spare patients from the harsh side effects of chemotherapy whenever possible.
Patients affected by the new findings, according to The Times, include women who have early-stage breast tumors measuring one to five centimeters that have not spread to lymph nodes; are sensitive to estrogen; test negative for the protein HER2; and have a score of 11 to 25 on a widely used gene test called Oncotype DX Breast Cancer Assay that gauges the activity of a panel of genes involved in cancer recurrence.
The test, which has been available since 2004, gives scores of zero to 100. Previous research has shown that scores 10 and under don’t call for chemotherapy, and scores over 25 do, according to The Times. But there’s been a lot of uncertainty about what to do with those in between, who are considered intermediate.
Many of those patients have been receiving chemotherapy because in 2000 the National Cancer Institute recommended it for most women, even those whose disease had not spread to lymph nodes, based on research indicating it could prevent the cancer from recurring elsewhere in the body and becoming incurable, according to Dr. Sparano.
“Some seemed to benefit and some didn’t,” Dr. Mayer said. “We were back to square zero, safe rather than sorry, giving chemo to a lot who didn’t need it.”
TAILORx came about after data emerged suggesting that intermediate women were not being helped by chemotherapy, and doctors began recommending it less often. The study, according to The Times, eventually included 10,253 women ages 18 to 75. They had surgery and radiation, and then were assigned at random to receive either endocrine therapy alone or endocrine therapy plus chemotherapy. After nine years, the two groups fared equally well.