CHICAGO – , sparing them adverse effects and preventing overtreatment, TAILORx trial results show.
The findings, which were reported in the plenary session at the annual meeting of the American Society of Clinical Oncology and simultaneously published in the, mark a major advance in precision medicine.
The recurrence score is known to be prognostic and to be predictive of benefit from adding chemotherapy to endocrine therapy, Dr. Sparano said. “But there was a major gap: There was uncertain benefit for patients who had a midrange score, about two-thirds of all patients who are treated.”
The phase 3 TAILORx trial registered 10,273 women with hormone receptor–positive, HER2-negative, node-negative early-stage breast cancer, making it the largest adjuvant breast cancer trial to date. Analyses focused on the 6,711 evaluable women with a midrange recurrence score (defined as 11 through 25 in the trial), who were randomized to receive endocrine therapy alone or adjuvant chemotherapy plus endocrine therapy, with a noninferiority design. Of note, contemporary drugs and regimens were used.
Results at a median follow-up of 7.5 years showed that the trial met its primary endpoint: The risk of invasive disease-free survival events (invasive disease recurrence, second primary cancer, or death) was not inferior for women given endocrine therapy alone compared with counterparts given chemotherapy plus endocrine therapy (hazard ratio, 1.08; P = .26), Dr. Sparano reported.
The groups were also on par, with absolute differences of no more than 1% between rates, with respect to a variety of other efficacy outcomes: freedom from distant recurrence and any recurrence, and overall survival.