As reported in the Journal of Clinical Oncology by François-Clément Bidard, MD, PhD, and colleagues, the French phase III STIC CTC trial showed a nonsignificant overall survival benefit with a circulating tumor cell (CTC) count–driven approach to therapy vs physician’s choice in the first-line treatment of hormone receptor–positive, HER2-negative advanced breast cancer. The primary analysis of the trial showed that CTC-driven therapy was noninferior to investigator’s choice in 2-year progression-free survival in this setting.
François-Clément Bidard, MD, PhD
In the multicenter open-label trial, 755 patients were randomly assigned between February 2012 and July 2016 to the CTC group (n = 378) or the standard group (n = 377). In the CTC group, patients received chemotherapy if their CTC count was ≥ 5 CTCs/7.5 ml (CTC-high) or endocrine therapy if their CTC count was lower (CTC-low). In the standard group, patients received chemotherapy for clinically high-risk disease (Clin-high) or endocrine therapy for clinically low-risk disease (Clin-low) at physician’s discretion.
Median follow-up was 4.7 years. Median overall survival was 51.3 months (95% confidence interval [CI] = 46.8–55.1 months) in the CTC group vs 45.5 months (95% CI = 40.9–51.1 months) in the standard group (hazard ratio [HR] = 0.85, 95% CI = 0.69–1.03, P = .11).
With additional follow-up, median progression-free survival was 15.7 months (95% CI = 12.8–17.4 months) in the CTC group vs 13.8 months (95% CI = 12.1–15.9 months) in the standard group (HR = 0.94, 95% CI = 0.81–1.09).
Patients with discordant Clin-low/CTC-high features had better outcomes with chemotherapy in the CTC group vs endocrine therapy in the standard group. Among these patients, median overall survival was 51.8 months (95% CI = 43.3 months to not reached) in the CTC group vs 35.4 months (95% CI = 30.4–45.4 months) in the standard group (HR = 0.53, 95% CI = 0.36–0.78, P = .001).
The investigators concluded: “[T]he STIC trial established the overall safety of using the CTC count as a standalone biomarker, and despite a lack of significant survival benefit in the general population, it showed that patients with a high CTC count and a low clinical risk estimate may derive a significant overall survival benefit from chemotherapy.”
Dr. Bidard, MD, PhD, of Institut Curie, Saint-Cloud, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by Institut Curie, the French National Cancer Institute, Menarini Silicon Biosystems, and others. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.