CTCs may predict risk for late breast cancer recurrence
medwireNews: Women with detectable circulating tumor cells (CTCs) at least 5 years after diagnosis of hormone receptor-positive breast cancer have a substantially increased risk for late clinical recurrence, clinical trial data show.
The secondary analysis of the Double-Blind Phase III Trial of Doxorubicin and Cyclophosphamide Followed by Paclitaxel With Bevacizumab or Placebo in Patients With Lymph Node Positive and High Risk Lymph Node Negative Breast Cancer “provides proof of concept that liquid-based biomarkers may be used to risk stratify for late recurrence and guide therapy,” say Joseph Sparano (Albert Einstein College of Medicine, New York, USA) and co-investigators.
Among 547 women with no clinical evidence of recurrence between 4.5 and 7.5 years after surgery and adjuvant systemic therapy for HER2-negative stage II–III breast cancer, 26 (4.8%) had a positive CTC assay result (at least 1 CTC per 7.5 mL of blood) when tested 5 or more years after diagnosis.
The CTC-positive rate was 5.1% in women with hormone receptor-positive disease (n=353), while the clinical recurrence rate in this group was 6.5% (n=23 cases).
The researchers report in JAMA Oncology that women with CTCs had a significant 13.1-fold higher risk for late recurrence than those with no CTCs, after adjustment for potential confounders, with a median time to recurrence of 2.8 years following a positive result.
The late recurrence rate was 21.4% per person–years of follow-up (seven recurrences per 32.7 person–years) in the CTC-positive group compared with 2.0% (16 recurrences per 796.3 person–years) in the CTC-negative group.
Although 4.1% of the 193 women with hormone receptor-negative disease also tested positive for CTCs, there was no association with late recurrence in this group. Indeed, only one hormone receptor-negative patient relapsed during the follow-up period and she had a negative CTC result, the researchers note.
Sparano and co-authors conclude that their findings support “further study of blood-based biomarker tests such as the CTC assay for early detection of late clinical recurrence and for identifying subjects at low risk of late recurrence.”
“Notwithstanding proof of concept, further evaluation is required to confirm the clinical validity and determine the clinical utility of performing the CTC assay in this context,” they add.
By Laura Cowen
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