Multicenter randomized trial of circulating tumor cell count-drive choice of therapy in advanced breast cancer: overall survival results

In patients with HR-positive, HER2-negative advanced breast cancer (aBC) the French multicenter randomized STIC CTC trial established that, for choosing between first-line endocrine therapy (ET) and chemotherapy, the use of circulating tumor cell (CTC) count is noninferior to the investigator’s choice in terms of progression-free survival. Overall survival (OS) results of the trial have now been published. Patients were 1:1 randomized to first-line treatment determined by investigators of based on CTC count (chemotherapy if ≥ 5 CTCs/7.5 ml; ET if lower CTC count). Median follow-up was 4.7 years. Median OS was 51.3 months in the CTC-based arm and 45.5 months in the standard arm (HR 0.85; p=0.11). Among patients with ET recommended by clinicians and high CTC count, chemotherapy was superior to ET (HR for death 0.53; p=0.001). The authors conclude that CTC ount may be a reliable biomarker for guiding the choice between chemotherapy and ET as first-line treatment in HR-positive, HER2-negative aBC.