Washington, May 16 : Doctors' dependence on radiology studies such as CT scans and ultrasound for breast cancer therapy could soon become passe, thanks to researchers at Georgetown University Medical Center, who have developed a simple blood test to reliably assess treatment response in patients with metastatic breast cancer.
The researchers conducted the study with aim to develop personalised cancer treatment for each individual.
"It can take several weeks and sometimes months to determine if a particular cancer treatment is working because it can take that long to observe any significant radiographic changes in tumor size or appearance," said Minetta Liu, M.D., of Georgetown's Lombardi Comprehensive Cancer Center.
She added: "Right now, we have to rely on radiology studies such as CT scans, ultrasound, and the like to determine whether or not there is disease progression. With this new blood test, we have another reliable tool that may allow us to determine much sooner if a therapy is ineffective so that we can change therapy earlier and potentially make more significant improvements in survival."
Making use of the FDA-approved CellSearch technology, the research team measured the number of circulating tumor cells (CTC) in blood collected from women with metastatic breast cancer. They collected about one tablespoon of blood every three to four weeks.
Then, they compared the number of CTCs with disease response or progression as determined by standard radiology studies performed every 9-12 weeks. Also, the patients in the study were provided with various treatments including chemotherapy, endocrine therapy, and combination therapy with a biologic agent.
Taking a CTC count of five as the threshold, the researchers observed a highly significant difference in the distribution of progression between two groups of patients defined by their CTC result. The results indicated that 71 percent of patients having CTC greater than or equal to 5 had disease progression, while 66 percent of patients with a CTC count of less than 5 did not.
"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. 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," explained Liu.
She stressed that the CTC assay is a more reliable means of assessing treatment response than the traditional tumor markers currently in use.
"We have many treatment options for advanced breast cancer. The key is to find the most effective therapy for each patient. It shouldn't take months to figure that out," she concluded.