medwireNews: Women with hormone receptor-positive, HER2-negative, axillary node-negative breast cancer who have a midrange score on the 21-tumor gene assay may be spared adjuvant chemotherapy, phase III study data show.
The TAILORx trial, which was presented at the ASCO Annual Meeting 2018 in Chicago, Illinois, USA, found that endocrine therapy alone was as good as chemoendocrine therapy for the prevention of invasive disease recurrence in women with a score of 16–25 on this 21-gene test.
In a statement to the press, lead study author Joseph Sparano, from the Montefiore Medical Center in New York, USA, said: “Half of all breast cancers are hormone receptor-positive, HER2-negative, and axillary node-negative. Our study shows that chemotherapy may be avoided in about 70 percent of these women when its use is guided by the test, thus limiting chemotherapy to the 30 percent who we can predict will benefit from it.”
He added: “Any woman with early-stage breast cancer 75 years or younger should have the [21-gene Oncotype DX Breast Recurrence Score test] and discuss the results of TAILORx with her doctor to guide her decision regarding chemotherapy after surgery to prevent recurrence.”
Among the 9719 women included in the prospective study, 6711 (69%) had a midrange recurrence score of 11 to 25 and were randomly assigned to receive either chemoendocrine therapy or endocrine therapy alone.
During a median 7.5 years of follow-up there were 436 cases of invasive disease recurrence, second primary cancer, or death among the women randomly assigned to endocrine therapy alone and 400 cases among those assigned to chemoendocrine therapy.
This corresponded to a nonsignificant hazard ratio of 1.08, indicating that endocrine therapy was noninferior to chemoendocrine therapy for invasive disease-free survival.
Indeed, at 9 years, the invasive disease-free survival rate was 83.3% in the endocrine therapy group and 84.3% in the chemoendocrine therapy group.
Corresponding rates for freedom from disease recurrence were 94.5% and 95.0% at a distant site, and 92.2% and 92.9% at a distant or local–regional site. The rates for overall survival were 93.9% and 93.8%, respectively.
Exploratory analyses showed that there were no significant interactions between chemotherapy treatment and tumor size, histologic grade, clinical risk category, or menopausal status, but there was an interaction with age.
Specifically, women aged 50 years and younger with a recurrence score of 16 to 25 who received chemotherapy had a lower rate of distance recurrence than women who received endocrine therapy alone, but overall survival rates were similar.
Writing in the New England Journal of Medicine, where the study was simultaneously published, Sparano and co-authors conclude: “The results of our trial suggest that the 21-gene assay may identify up to 85% of women with early breast cancer who can be spared adjuvant chemotherapy, especially those who are older than 50 years of age and have a recurrence score of 25 or lower, as well as women 50 years of age or younger with a recurrence score of 15 or lower.”
ASCO Expert Harold Burstein, from Harvard Medical School in Boston, Massachusetts, USA, said in a press statement that the TAILORx study provides “critical reassurance to doctors and patients that they can use genomic information to make better treatment decisions in women with early-stage breast cancer.”
He added: “Practically speaking, this means that thousands of women will be able to avoid chemotherapy, with all of its side effects, while still achieving excellent long-term outcomes.”
By Laura Cowen
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