Patients with early-stage, node-negative, hormone receptor (HR)-positive, HER2-negative breast cancer and a high risk of recurrence, as determined by the OncotypeDX genomic test, experienced improved outcomes when treated with adjuvant anthracycline- plus taxane-based chemotherapy (T-AC) regimens. The findings, presented at the San Antonio Breast Cancer Symposium (SABCS) 2024, suggest a potential benefit of more intensive chemotherapy for this specific patient population.
Study Details and Findings
The study, led by Dr. Nan Chen from the University of Chicago Medicine, analyzed data from the TAILORx trial, comparing outcomes of patients with stage I/II, node-negative, HR-positive, HER2-negative breast cancer who received either T-AC or taxane with cyclophosphamide (TC) chemotherapy after surgery. The OncotypeDX test, which provides a recurrence score (RS) between 0 and 100, was used to predict which patients might benefit from chemotherapy.
Patients with an RS between 11 and 25 were randomly assigned to receive endocrine therapy alone or endocrine therapy plus a chemotherapy regimen. Those with an RS over 26 received endocrine therapy plus a chemotherapy regimen. Of the 2,639 eligible cases, 2,197 patients received TC, while 442 were treated with T-AC, which included anthracycline with cyclophosphamide followed by taxane; concurrent anthracycline, cyclophosphamide, and docetaxel; or other anthracycline with taxane combinations.
After controlling for factors such as age, grade, tumor size, and estrogen/progesterone receptor status, the use of T-AC in patients with an RS of 31 or greater and tumors 2 cm or greater was associated with improved survival outcomes after five years. Specifically, patients who received T-AC had a higher distant recurrence-free interval (96.1% vs. 90.7%), distant recurrence-free survival (95.4% vs. 89.5%), and recurrence-free interval (94.1% vs. 89.1%) compared to those who received TC. There was also a trend towards improved recurrence-free survival (93.4% vs. 87.9%) and overall survival at five years (97.3% vs. 93.1%).
Clinical Implications and Considerations
"These results are in line with current clinical practice, where we give anthracyclines more readily in tumors biologically closer to triple-negative disease," said Dr. Chen. She added that the benefit of anthracycline therapy increased as the RS increased above 31, with no trend toward benefit seen in patients with a score between 26 and 30.
While the study suggests a potential benefit of anthracycline-based regimens, Dr. Chen cautioned that the early benefit in recurrence reduction may be offset by the late risk of non-breast cancer deaths, such as leukemia. Longer-term follow-up is needed, and these risks should be discussed with patients before considering anthracycline-based chemotherapy.
Limitations and Future Directions
Limitations of this study include its post-hoc analysis of the TAILORx study, which was not specifically designed to evaluate the benefit of anthracyclines. Additionally, the benefits of anthracyclines in lower-risk patients (RS 26-30) may have been difficult to measure due to the overall lower risk of recurrence in this population.
Dr. Chen and her colleagues plan to further validate these findings and examine the use of anthracyclines in other patient groups, including those with node-positive disease. They also aim to investigate the impact of novel therapies, such as CDK4/6 inhibitors, on the role of chemotherapy and anthracyclines in early breast cancer treatment.
