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Can Circulating Tumor Cell Count Guide First-Line Chemotherapy or Endocrine Therapy for HR-Positive, HER2-Negative Metastatic Breast Cancer?


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In the French phase III STIC CTC trial reported in JAMA Oncology, François-Clément Bidard, MD, PhD, and colleagues found that choice of first-line chemotherapy vs endocrine therapy in hormone receptor (HR)-positive, HER2-negative metastatic breast cancer based on circulating tumor cell count resulted in noninferior progression-free survival vs clinician choice.

Study Details

In the multicenter trial, 755 pre- or postmenopausal women (per-protocol population) were randomly assigned between February 2012 and July 2016 to a circulating tumor cell­–driven group (n = 377), in which patients received chemotherapy for circulating tumor cell counts  of ≥ 5/7.5 mL (CTC-high) and endocrine therapy for counts < 5/7.5 mL (CTC-low) or a clinician choice group (standard group, n = 378), in which patients received chemotherapy or endocrine therapy based on clinician assessment of high or low risk (clinical-high, clinical-low). The primary endpoint was progression-free survival after 2 years, with a noninferiority margin of 1.25 for the 90% confidence interval (CI) of the hazard ratio (HR).


"This randomized clinical trial found that the circulating tumor cell count may be a reliable biomarker method for guiding the choice between chemotherapy and endocrine therapy as the first-line treatment in hormone receptor–positive, HER2-negative metastatic breast cancer."
— François-Clément Bidard, MD, PhD, and colleagues

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Progression-Free Survival

Overall, 37% of the circulating tumor cell group vs 27% of the standard group received chemotherapy. Median progression-free survival was 15.5 months (95% CI = 12.7–17.3 months) in the circulating tumor cell group vs 13.9 months (95% CI = 12.2–16.3 months) in the standard group; the hazard ratio was 0.94, with a 90% confidence interval of 0.81–1.09, which met the noninferiority criterion. Median overall survival was 47.3 months vs 42.8 months (HR = 0.91, 95% CI, 0.71–1.16).

Analyses according to concordant and discordant circulating tumor cell and clinician-assessed status showed median progression-free survival for the circulating tumor cell vs standard groups of 17.3 vs 18.8 months (HR = 1.03, 95% CI = 0.81­–1.31) in the clinical-low/circulating tumor cell–low subgroup, 11.3 vs 11.0 months (HR = 0.90, 95% CI = 0.60­­–1.36) in the clinical-high/circulating tumor cell–high subgroup, 8.1 vs 14.1 months (HR = 1.20, 95% CI = 0.79–1.84) in the clinical-high/circulating tumor cell–low subgroup, and 15.6 vs 10.0 months (HR = 0.62, 95% CI = 0.45–0.84) in the clinical-low/circulating tumor cell–high subgroup.   

Adverse Events

The incidence of grade 3 or 4 adverse events was low in both groups. The incidence of chemotherapy-related adverse events of any grade was higher in the circulating tumor cell group, including anemia (20.4% vs 14.6%), alopecia (15.1% vs 10.6%), and vomiting (8.2% vs 4.8%).

The investigators concluded, “This randomized clinical trial found that the circulating tumor cell count may be a reliable biomarker method for guiding the choice between chemotherapy and endocrine therapy as the first-line treatment in hormone receptor–positive, HER2-negative metastatic breast cancer.”

Dr. Bidard, of the Department of Medical Oncology, Institut Curie, is the corresponding author for the JAMA Oncology article.

Disclosure: The study was funded by Institut Curie, French National Cancer Institute, and Menarini Silicon Biosystems. For full disclosures of the study authors, visit jamanetwork.com.

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®.
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