Posted: Friday, January 20, 2023
After a 5-year follow-up, high circulating tumor cell (CTC) count appears to be discordant in 40% of patients with estrogen receptor–positive, HER2-negative metastatic breast cancer. Additionally, François-Clément Bidard, MD, PhD, of Institut Curie and Versailles Saint-Quentin University, Paris, and colleagues proposed that CTC may be employed to adjust systemic treatment for metastatic breast cancer in second and later lines, after disease progression on CDK4/6 inhibitors. These findings were presented at the 2022 San Antonio Breast Cancer Symposium (SABCS; Abstract GS3-09).
“Interestingly, the subgroup of patients with concordant favorable estimates by clinician assessment and CTC count—representing 48% of the study population—had a median overall survival of about 5 years, even though these patients did not receive [CDK4/6] inhibitors as part of their first-line treatment,” said Dr. Bidard in an SABCS press release.
The STIC CTC trial randomly assigned patients with metastatic breast cancer to either chemotherapy or endocrine therapy, decided by the investigator (n = 378) or the CTC count (n = 377). In the standard arm, chemotherapy was chosen for clinical high-risk patients, and endocrine therapy, for clinical low-risk participants.
A total of 755 patients were included in the study. Of them, 189 (25.0%) had clinical low-risk/CTC-high profiles, 103 (13.6%) had clinical high-risk/CTC-low profiles, 363 (48.2%) had clinical low-risk/CTC-low profiles, and 100 (13.2%) had clinical high-risk/CTC-high profiles. The median follow-up time was 57 months.
In the clinical low risk/CTC-high subgroup, chemotherapy in the CTC arm had a longer overall survival of 51.8 months compared with endocrine therapy in the standard arm at 35.4 months. In the clinical high-risk/CTC-low subgroup, no significant differences were observed in the chemotherapy or endocrine therapy arm. Additionally, all concordant and discordant groups had a median overall survival of 45.5 months and 51.3 months in the standard and CTC arms, respectively.
Disclosure: For full disclosures of the study authors, visit aacr.com