Using circulating tumor cell (CTC) count to determine whether chemotherapy or endocrine therapy is used improves survival outcomes compared with clinically determined treatment in patients with hormone receptor (HR)-positive, HER2-negative metastatic breast cancer, according to the results of the open-label, randomized phase 3 STIC CTC trial published today in JAMA Oncology.
The investigators, led by François-Clément Bidard, MD, PhD, Professor of Medicine at the University of Paris-Saclay and Research Physician in Medical Oncology at the Institut Curie, compared CTC count–driven versus clinician-driven therapy approaches in 755 premenopausal and postmenopausal women with HR-positive, HER2-negative metastatic breast cancer from February 1, 2012, to July 28, 2016. The authors evaluated progression-free survival as the primary end point and median overall survival as a secondary one.
Of 377 patients in the CTC count-driven arm, the 36.6% of patients who were CTC high received chemotherapy, while the 63.4% of patients who were CTC low received endocrine therapy. Of 387 patients in the clinician-driven arm, 27.2% of patients who were considered clinical high received chemotherapy, and 72.7% who were considered clinical low received endocrine therapy. Overall, 61.3% of patients had a clinical risk assessment that was concordant with their CTC risk. The CTC count-driven treatment produced a longer median progression-free survival (15.5 vs 13.9 months) and a longer median overall survival (47.3 vs 42.8 months) compared with standard clinician-driven treatment.
Regarding chemotherapy-related adverse events of any grade, patients in the CTC count-driven treatment arm experienced higher incidence of anemia compared with the standard arm (20.4% vs 14.6%), as well as higher incidence of alopecia (15.1% vs 10.6%) and vomiting (8.2% vs 4.8%).
"In the overall population, the STIC CTC trial reached its primary objective and reported no overt survival difference between the two arms. While the overall rate of chemotherapy use was not lower in the CTC arm, the reproducibility of the CTC could allow for treatment standardization in this population," conclude Dr. Bidard and colleagues. "The apparent superior benefit of the CTC-based strategy in older adult patients might stem from the observed significant association between older age and more systematic use of endocrine therapy as the clinically favored treatment whatever the other clinicopathologic characteristics. Using the CTC count as a single biomarker is therefore a reliable standardized option to guide the treatment choice between single-agent endocrine therapy and chemotherapy in hormone receptor–positive, [HER2]-negative metastatic breast cancer."
For More Information
Bidard FC, Jacot W, Kiavue N, et al (2020). Efficacy of circulating tumor cell count–driven vs clinician-driven first-line therapy choice in hormone receptor–positive, ERBB2-negative metastatic breast cancer: the STIC CTC randomized clinical trial. JAMA Oncol. [Epub ahead of print] DOI:10.1001/jamaoncol.2020.5660
Image credit: Ed Uthman. Licensed under CC BY 2.0