In the near future, a blood test that measures the number of tumor cells circulating in the blood, sometimes referred to as a “liquid biopsy,” may be used to predict the chance that breast cancer may recur. In a recent study, measuring circulating tumors cells (CTCs) in patients with metastatic breast cancer using a test cleared by the FDA (CELLSEARCH®) was found to be a biomarker that predicted late recurrence among patients with hormone receptor (HR)-positive, HER2-negative early breast cancer.
In this population of patients, late recurrences (defined as those that occur ≥5 years after initial diagnosis) account for approximately 50% of recurrences in HR-positive breast cancers, noted the study’s lead investigator Joseph A. Sparano, MD, Associate Director for Clinical Research, Montefiore Einstein Center for Cancer Care, Albert Einstein Cancer Center, New York, NY.
The results from this study provide “proof of concept” that the presence of CTCs is a biomarker for late recurrence of disease.
“To our knowledge, this is the first report showing that a liquid-based biomarker is robustly prognostic for late recurrence,” said Dr Sparano.
The data also support the concept that therapy for patients might be tailored based on the blood biomarker test results.
This study, the details of which were presented at the 2017 San Antonio Breast Cancer Symposium, included 546 patients drawn from a larger study that tested the effect of adding bevacizumab (Avastin) to chemotherapy as adjuvant treatment following surgery. The patients selected had no recurrence of breast cancer 4.5 to 7.5 years after an initial diagnosis of HER2-negative stage II-III disease.
Thirty-five percent of patients who had blood samples were HR-negative. Eighty-eight percent of patients with estrogen receptor–positive disease were taking endocrine therapy at the time of their CTC sample. At a follow-up of 1.8 years, 4.0% of HR-positive patients and 0.5% of HR-negative patients had a breast cancer recurrence.
Overall, 4.8% of patients had a positive CTC assay result, including 5.1% of HR-positive patients and 4.1% of the HR-negative patients.
In the 353 patients with HR-positive disease, CTC-positive patients had a 21.7-fold higher risk for recurrence compared with the CTC-negative group. The median time to recurrence in CTC-positive patients was 1.6 years. A positive CTC assay was not associated with recurrence in the HR-negative group.
The results were somewhat unexpected, according to Dr Sparano. “We were surprised to see that 5% of patients had CTCs about 5 or more years after their initial diagnosis,” he said. “Although we were expecting that CTC-positive patients would have a higher recurrence rate, we weren’t expecting the risk of recurrence to be this high after a relatively short period of time.”
Further study is needed to confirm the clinical utility of this information, he added. For instance, it may be possible that patients can be spared extended adjuvant endocrine therapy if they have a negative CTC assay, indicating a low risk for recurrence.
Sparano JA, O’Neill A, Alpaugh K, et al. Circulating tumor cells (CTCs) five years after diagnosis are prognostic for late recurrence in operable stage II-III breast cancer. Presented at: 2017 San Antonio Breast Cancer Symposium; December 5-9, 2017. Abstract GS6-03.