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Tumor genome testing may reduce overtreatment of early-stage breast cancer
The use of the 21-gene recurrence score assay improved treatment decision-making and personalized the use of chemotherapy for women with early-stage breast cancer, according to a study published in Cancer.
Researchers found that only 3% of patients who received favorable results with the 21-gene recurrence score (Oncotype DX, Genomic Health) still elected to undergo chemotherapy, compared with 13% of women who had favorable prognoses but did not have the gene assay.
“The idea of precision medicine is to give patients the treatments that are the most likely to help and avoid needless side effects,” Christopher Friese, PhD, RN, professor at University of Michigan School of Nursing, said in a press release. “Chemotherapy has substantial side effects. Improving chemotherapy recommendations to those who truly stand to benefit would reduce complications and improve quality of life for many women.”
Friese and colleagues conducted a survey from 2013 to 2014 of 1,527 women from Georgia and Los Angeles County, California, with early-stage ER/PR–positive, HER-2–negative breast cancer. Of those surveyed, 778 women had received the 21-gene recurrence score, which estimates the risk for disease recurrence and the benefit of chemotherapy for ER–positive breast cancer. Of these women, 62.6% had node-negative, more favorable disease; 24.3% had node-negative, less favorable disease; and 13% had node-positive disease.
“We found that most doctors were using tumor genomic tests in ways that were recommended by professional guidelines, although we found that some patients were having the test where there is no professional recommendation for the test,” Friese said. “For example, about 13% of women whose lymph nodes were positive for breast cancer had tumor genomic testing, even though currently it is still under study whether women with positive lymph nodes will benefit from testing and resulting recommendations.”
Among women who underwent testing, 47.2% reported that their clinicians recommended against chemotherapy, 40.5% said their clinicians recommended chemotherapy, and 12.3% reported their oncologist left the decision up to them.
Clinician recommendations appeared highly associated with recurrence scores. Most patients with high scores (scores 31-100) received a recommendation for chemotherapy (86.9%-96.5% across subgroups), whereas most patients with low scores (scores 0-18) received a recommendation against chemotherapy (65.9%-78.2% across subgroups).
Among those whose score indicated they had a high risk for recurrence, 87% of those with node-negative favorable disease, 91.1% of those with node-negative less favorable disease, and 100% of those with node-positive disease elected to undergo chemotherapy.
Low scores were associated with a low rate of chemotherapy receipt across patients with node-negative favorable disease (2.9%), node-negative less favorable disease (9.5%) and node-positive disease (26.6%).
Chemotherapy receipt was more common in women who did not undergo testing compared with women who received low scores among those with node-positive disease (83.2% vs. 27.7%) and node-negative favorable disease (13% vs. 3%).
Among those women given the test, 63.9% reported it was “very” or “extremely” helpful. Sixty-five percent indicated low-risk scores shifted their decision against chemotherapy, and 73.1% indicating high-risk scores shifted them toward receipt of chemotherapy.
Friese and colleagues noted their study included a large, contemporary, diverse population-based sample of women but acknowledged it was limited to two large geographic regions in the United States. Further, physicians were not surveyed for the study.
Researchers also reported only 60% of patients accurately recalled their test results, noting many patients deferred interpretation of their test scores to their physicians.
“This suggests that while precision medicine for breast cancer has left the station, we have also left some women behind,” Friese said. “The oncology community needs to do a better job explaining to women the purpose of these tests, how to interpret the results, and what the results mean for their breast cancer treatment.”– by Chuck Gormley
Disclosure: The study was funded by a grant from the NCI. Friese reports no relevant financial disclosures. One researcher reports research funding for work performed outside the current study from Ambry Genetics, GenDx, Genomic Health, Invitae and Myriad Genetics.