Some women with early-stage hormone receptor–positive breast cancer can be treated with adjuvant hormone therapy alone, avoiding chemotherapy without increasing their risk of recurrence, according to results of a new study presented at the 2015 European Cancer Congress (ECC) in Vienna (abstract 5BA).
The results of the study—TAILORx (Trial Assigning Individualized Options for Treatment)—were also published in the New England Journal of Medicine.
In the study, forgoing chemotherapy in patients with a low risk of recurrence, as deemed by the Oncotype Dx recurrence score genetic assay, did not increase the risk of disease recurrence or disease spread at 5 years. These patients had a less than 2% risk of recurrence within 5 years. Rates of recurrence were not common, irrespective of the histologic grade of the tumor.
The trial enrolled 10,253 women with localized, hormone receptor–positive, HER2-negative breast cancer that had not spread to the lymph nodes. Patients were assessed with the OncotypeDx recurrence score test. A total of 1,626 women (15.9%) enrolled had a low recurrence risk score (< 10) and could receive tamoxifen, an aromatase inhibitor, or a combination of the two for 5 years, but not chemotherapy.
During the 5-year period there were 88 cases of either invasive cancer or death as well as 30 deaths from other causes. The rate of invasive disease-free survival at 5 years was 93.8%. The overall survival rate was 98%.
The rate of freedom from recurrence of breast cancer at a distant site was 99.3%, and the rate of freedom from recurrence of breast cancer at a distant or local–regional site was 98.7%.
The study is the first prospective study that has evaluated OncotypeDx, a 21-gene assay used for independent prognostic information in addition to clinical and pathologic tumor features. The addition of chemotherapy to adjuvant endocrine therapy can reduce the risk of recurrence by about 30%, but many estrogen receptor–positive patients are overtreated with chemotherapy based on clinical and pathologic tumor features alone.
“These results cannot come soon enough, given the already widespread adoption of the test as a key component of guidelines and routine clinical decision-making,” wrote Clifford A. Hudis, MD, of the Memorial Sloan Kettering Cancer Center in New York, in an accompanying editorial. “This result is numerically good enough to exclude any potentially meaningful benefit for additional chemotherapy.”
But, Hudis noted, “for the many physicians already using the test, the gap between this cutoff point of 10 and the higher ‘standard’ cutoff point of 18 may be a concern.” Furthermore, said Hudis, “others will wonder whether chemotherapy is beneficial or indicated even in patients with scores up to 25.”