Monitoring of circulating tumor DNA allows early detection of disease relapse in patients with operable breast cancer: case-control study

Breast cancer is known for late recurrences. A case-control study at Stavanger University Hospital (Norway) evaluated circulating tumor DNS (ctDNA) monitoring for early detection of systemic relapse of breast cancer after curative treatment. The study included 35 patients with relapse and 35 patients without relapse, with blood samples collected every 6-12 months during a median follow-up of 8.3 years. ctDNA was analyzed by targeted DNA sequencing, and results were compared to genetic analyses of tumor and metastasis biopsies. ctDNA was detected at relapse in 19 of 35 (54%) patients, and preceded clinical or radiological relapse detection in 17 patients, with a median lead time of 10.3 months. In 13 (68%) patients, there was concordance with tumor mutations, and in seven patients, there was also concordance with metastases. Among the relapse-free patients, seven were ctDNA-positive postsurgery, and only one of them had a match among the tumor variants. The authors conclude that these findings suggest that serial ctDNA analysis may enable earlier detection of systemic relapse in patients with operable breast cancer.