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Circulating tumor cells associated with late breast cancer recurrence
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A positive circulating tumor cell assay result 5 years after diagnosis of hormone receptor-positive breast cancer predicted risk for late clinical recurrence, study data showed.
“Recurrence 5 years or more after a diagnosis is commonly referred to as late recurrence and accounts for approximately one-half of all recurrences of hormone receptor-positive breast cancer, whereas recurrence 5 years or more after diagnosis is considerably less common among patients with hormone receptor-negative disease,” Joseph Sparano, MD, professor of medicine at Albert Einstein College of Medicine, and colleagues wrote.
“Biomarkers that more robustly stratify risk are needed,” the researchers added. “Assays that use blood-based biomarkers such as circulating tumor cells (CTCs) or circulating tumor DNA (so-called liquid biopsies) have potential to address this unmet need but have not been evaluated for use in determining late recurrence in breast cancer.”
The researchers performed a per-protocol secondary analysis of 547 women who participated in a double-blind, phase 3 trial that evaluated doxorubicin and cyclophosphamide followed by paclitaxel with either bevacizumab (Avastin, Genentech) or placebo. All patients were recurrence free between 4.5 and 7.5 years after being treated for HER-2-negative stage II to III breast cancer.
Sparano and colleagues obtained blood samples from patients for identification and enumeration of CTCs.
The association between positive CTC assay results — defined as at least one CTC per 7.5 mL of blood — and late recurrence served as the main outcome.
Median follow-up after the CTC assay was 2.6 years (range, 1.6-4.4).
Among 353 women with hormone receptor-positive disease, 18 (5.1%; 95% CI, 3-7.9) had a positive CTC assay.
Twenty-three patients (6.5%; 95% CI, 4.2-9.6) in the hormone receptor-positive population experienced recurrence.
The recurrence rate was 21.4% (seven recurrences per 32.7 person-years) among patients who tested positive for CTCs, compared with 2% (16 recurrences per 796.3 person-years) among those who tested negative.
A positive assay result was associated with a 13.1-fold increase in risk for recurrence (HR = 13.1; 95% CI, 4.7-36.3).
Seven patients who experienced recurrence had a positive assay a median 2.8 years before clinical recurrence (range, 0.1 to 2.8 years).
Eight of 193 patients (4.1%; 95% CI, 1.8-8) with hormone receptor-negative disease also had positive CTC assay results; however, just one patient with hormone receptor-negative disease experienced recurrence (0.5%; 95% CI, 0-2.9). This patient also had a negative assay.
“The results of this study provide proof of concept supporting 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 [for] late recurrence,” the researchers wrote. “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.” – by Andy Polhamus
Disclosures: The authors report no relevant financial disclosures.
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Sparano J, et al. JAMA Oncol. 2018;doi:10.1001/jamaoncol.2018.2574.
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