By Will Boggs MD
NEW YORK (Reuters Health) - 3/10/2019
Adjuvant chemotherapy added to endocrine therapy for early breast cancer with a high 21-gene recurrence score (RS) may improve clinical outcomes, according to a secondary analysis of the TAILORx randomized clinical trial.
"Results of the 21-gene RS are critical in driving treatment decisions about use of adjuvant chemotherapy in early-stage estrogen-receptor-positive (ER+), HER2-negative breast cancer," Dr. Joseph A. Sparano of Montefiore Medical Center, in New York City, told Reuters Health by email.
A high RS independently predicts not only a high distant recurrence rate, but also a significant benefit from chemotherapy. In TAILORx, adjuvant chemotherapy provided no additional benefit over endocrine therapy in the overall population of women with an RS of 11 to 25, but there was a suggestion of chemotherapy benefit in women aged 50 years or younger whose RS was 16 to 25.
In the current study, Dr. Sparano and colleagues evaluated clinical outcomes, characteristics and adjuvant chemotherapy regimens for women in TAILORx with early breast cancer with an RS of 26 to 100 assigned to receive chemotherapy plus endocrine therapy.
Overall, 1,389 women were included in the analysis, including 598 (42%) who had an RS of 26 to 30, and 791 (58%) who had an RS of 31 to 100.
Among the 1,300 women who received adjuvant chemotherapy, the rate of freedom from recurrence of breast cancer at a distant site was 93.0% at five years and 86.8% at nine years (94.6% and 88.5%, respectively, for those with an RS of 26 to 30, and 91.9% and 85.5% for those with an RS of 31 to 100), the researchers report in JAMA Oncology, online September 30.
By comparison, the expected rates of freedom from distant recurrence with endocrine therapy alone were lower, at 78.8% and 65.4% overall, respectively; 89.6% and 80.6% for those with an RS of 26 to 30; and 70.7% and 54% for those with an RS of 31 to 100.
"Testing for ER/PR (progesterone receptor) and HER2 is critical for directing therapy in breast cancer," Dr. Sparano concluded. "Use of the 21-gene RS should now be considered an essential test in most cases of early-stage breast cancer that meet criteria to testing."
Dr. Terry P. Mamounas of Orlando Health UF Health Cancer Center, in Florida, who has researched various treatments for breast cancer, told Reuters Health by email, "These results underscore the high rates of recurrence of node-negative, ER-positive patients with high recurrence score (>25) and the potential for substantial benefit from adjuvant chemotherapy, as it has been previously shown from the B-20 trial."
Physicians should "recommend adjuvant chemotherapy for this group of high-risk node-negative, ER-positive patients," said Dr. Mamounas, who was not involved in the study.
JAMA Oncol 2019.
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