CTC matches MD judgment for mBC therapeutic choice

SAN ANTONIO – For patients with estrogen-receptor positive, HER2-negative metastatic breast cancer, the use of circulating tumor cell (CTC) counts can help clinicians decide with confidence between ordering first-line hormonal therapy or chemotherapy, investigators say.

In the phase 3 STIC CTC trial, patients were randomly assigned to receive therapy based on either the clinician’s judgment of the best course of therapy for each patient; or on the CTC count with a cutoff of less than 5 CT/7.5 mL, indicating hormonal therapy; and 5 CTC/7.5 mL or above, indicating higher-risk disease requiring chemotherapy. In the clinician’s choice arm, the CTC reading was recorded but not implemented, and in the CTC arm, the clinician’s choice was dismissed.

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The trial met its primary noninferiority endpoint, indicating that, in the overall population, CTC counts can provide clinician’s with confidence in the therapeutic choice, said Francois-Clement Bidard, MD, PhD, from Institut Curie in Paris.

In a video interview, Dr. Bidard discussed the trial findings, including the provocative exploratory analysis suggesting that, in patients in whom there is discordance between CTC and clinician choice, chemotherapy may be a better therapeutic option.

The study was funded by the National Cancer Institute of France, Institut Curie, and Menarini Silicon Biosystems. Dr. Bidard disclosed research funding and travel grants from Menarini.