It’s quite frustrating really. It normally takes several weeks or even months to find out if a particular cancer treatment is working. Doctors normally rely on computer tomography (CT) scans or ultrasonography to determine if the patient is responding to the treatment or not and it takes that long to see if there are any significant radiographic changes in the size and appearance of the tumor.
A new blood test developed by researchers at Georgetown University Medical Center may solve this problem – and reduce the waiting time and costs. Their study showed that a simple blood test can help doctors assess the effect of cancer treatments on patients with metastatic breast cancer faster than the conventional way. This will allow the doctors to determine sooner if the therapy is effective or not so that they can change the treatment earlier and may give the patients higher chance of survival.
The researchers studied the blood collected from women with metastatic breast cancer using the FDA-approved Cellsearch technology. The women patients who participated in the research were receiving various cancer treatments including chemotherapy, endocrine therapy and other combination therapies. One tablespoon of blood was collected from them every three to four weeks and the number of circulating tumor cells (CTC) in the blood was counted. The number of CTCs was matched with the disease progression or treatment response as determined by radiographic analysis done every 9 to12 weeks. The threshold levels of 5 CTC readings were used as based on a previous research. The results showed that 71% of the patients with CTC equal to five or higher have disease progression. Sixty-six percent of the patients, however, with a CTC count of less than five have no disease progression.
“A CTC count of five or greater at the time of restaging was associated with a 5.32 fold increase in a patient’s chance of having disease progression compared to CTC counts of less than five,” according to Dr. Minetta Liu of Georgetown’s Lombardi Comprehensive Cancer Center. “CTC assessments should be used as a surrogate marker for treatment efficacy and disease responsiveness. Changes in CTC results from less than five to greater than or equal to five over time may herald disease progression.”
Lui also stated that using CTC method is a more reliable way of assessing the response to cancer treatment compared to the traditional tumor markers used currently. They are now working on a follow-up study to evaluate the CTC results to eliminate possible variability from the different treatments used.
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