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Circulating tumor cells predict risk for late breast cancer recurrence
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SAN ANTONIO — Circulating tumor cells showed clinical validity as a prognostic biomarker for late recurrence of hormone receptor-positive, HER-2-negative early breast cancer, according to study results presented at the San Antonio Breast Cancer Symposium.
Women with circulating tumor cells (CTCs) detected 5 years after diagnosed had increased risk for late recurrence, results showed.
“Late recurrence in ER-positive breast cancer is a huge clinical problem,” Joseph A. Sparano, MD, of Montefiore Medical Center at Albert Einstein School of Medicine, said in a press conference. “Some experts in the field have dubbed this to be the next frontier of research.”
Previous findings that showed adjuvant chemotherapy provided incremental benefit in preventing late recurrence — which Sparano described as recurrence 5 or more years after initial diagnosis — fueled the current study.
“We know that adjuvant chemotherapy predominantly decreases early recurrence within the first 5 years of diagnosis,” he said. “More recently, we’ve come to recognize that extended adjuvant chemotherapy can provide some incremental benefit.”
Researchers hypothesized that using CellSearch Circulating Tumor Cell kit (Menarini Silicon Biosystems), an FDA-approved blood test, to detect CTCs would be beneficial in identifying women who might benefit from extended adjuvant endocrine therapy, or novel strategies to reduce late recurrence risk.
“We know that the presence of CTC burden is associated with a prognosis in metastatic breast cancer,” Sparano said.
The analysis included 546 patients without clinical evidence of recurrence between 4.5 to 7.5 years (median, 5.2 years) after an initial diagnosis of HER-2-negative, stage II to stage III breast cancer enrolled in trial E5103. All patients underwent surgery and adjuvant chemotherapy and endocrine therapy for at least 5 years if hormone receptor positive.
Time to recurrence served as the study’s primary endpoint.
Median follow-up following the CTC test was 1.8 years (range, 0-3.9).
Recurrence occurred among 4% (95% CI, 3-7.9) of 353 women with hormone receptor-positive disease and 0.5% (95% CI, 0-2.9) of those with hormone receptor-negative disease.
“This actually confirmed what we had known, which is that hormone receptor-positive disease is associated with later recurrence,” Sparano said. “We found only one recurrence in women with hormone receptor-negative disease. It was a locoregional recurrence.”
Sparano reported that they detected CTCs among 4.8% (95% CI, 3.1-6.9) of patients overall, or 5.1% (95% CI, 3-7.9) of patients with hormone receptor-positive breast cancer and 4.1% (95% CI, 1.8-9) of those with hormone receptor-negative disease.
“There didn’t seem to be much of a difference hormone receptor-positive and -negative groups,” Sparano said.
The researchers conducted a subgroup analysis for the 353 patients with hormone receptor-positive breast cancer. Recurrence occurred among 24.7% of patients in this cohort who were CTC positive, whereas only 1.5% of CTC-negative patients experienced recurrence. This resulted in a nearly 22-fold increase in breast cancer recurrence for patients with a positive CTC test (HR = 21.7; 95% CI, 7-67.8).
“A very strong association persisted,” Sparano said, in a multivariable analysis that adjusted for age, tumor status, node size and grade (HR = 18.1; 95% CI, 5-65.3).
The positive-predictive value of CTCs for 2-year recurrence was 35%, with a negative-predictive value of 98%.
“This provides level-one evidence supporting CTCs as a biomarker prognostic for late recurrence in the specific subgroup of patients with hormone receptor-positive, HER-2-negative early breast cancer, which accounts for about two-thirds of all breast cancers,” Sparano said.
He suggested that a second treatment decision point 5 years after diagnosis may be useful for clinicians to consider.
“We still have work to do to really nail down what the clinical utility of this information is,” he added. – by Rob Volansky
Reference:
Sparano JA, et al. Abstract GS6-03. Presented at: San Antonio Breast Cancer Symposium; Dec. 5-9, 2017; San Antonio.
Disclosures: The authors report no relevant financial disclosures.
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Jennifer K. Litton, MD
Looking at CTCs, we know that if they decrease when we give treatment for metastatic breast cancer, there is a better prognosis. Looking at this as a tool to identify patients who are going to recur earlier has always been intriguing. We still need to not only identify who might recur, but we also need to find a set treatment for who might benefit. This is intriguing from the standpoint of clinical trial development as we develop strategies for further prevention of recurrence. But its not yet ready, in my opinion, for standard practice.
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C. Kent Osborne, MD
I look at this in a different way. Can you go back now and look at patients with positive CTCs who recurred vs. those with positive CTCs who didn’t recur, and see if there is something that might explain this at the beginning?
This is an intriguing result, but we don’t know what to do with the data yet. This is similar to its use in metastatic disease, where you can put a patient in a category of worse prognosis depending on how many CTCs they had. But, this didn’t help us change the therapy, as all of those patients were on treatment anyway. What really needs to be done now is a study of whether to treat patients now based on CTCs or wait until they recur.
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