Test Can Help Patient Determine Treatment Changes Earlier
A simple blood test could tell women with advanced breast cancer whether or not their treatments are working earlier than current methods. With the goal of tailoring cancer treatment for each individual, Minetta Liu, MD, researcher at Lombardi Comprehensive Cancer Center and breast oncologist at Georgetown University Hospital, is studying this test with the hope that it will help doctors more reliably assess treatment efficacy for patients with metastatic breast cancer.
"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 Dr. Liu. "With this new blood test, we have a tool that might 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."
One of Dr. Liu's patients, fifty-year-old Anne Crupi of Maryland, was diagnosed with stage-four breast cancer in October 2005. Anne received chemotherapy and radiation and then underwent various scans to determine if her treatments were working. In addition, as a part of Dr. Liu's study, Anne has a tube of blood drawn every month to see if there are cancer cells circulating in her blood stream. "I just think that if I can learn earlier that my chemo isn't working, if it stops working, then I can switch treatments without having to wait too long. I thought if it would help me or someone else, I would be happy to do it."
Using the FDA-approved CellSearch™ technology, Dr. Liu and colleagues at Georgetown University Hospital measured the number of circulating tumor cells (CTC) in blood collected from women with metastatic breast cancer. The number of CTCs was correlated with disease response or progression as determined by standard radiology studies.
Based on previous research, a CTC count of five was used as the threshold. Dr. Liu and her colleagues observed a big difference between patients with CTC levels of 5 and above compared to those below 5. Seventy-one percent of patients who had a CTC count greater than or equal to five had disease progression, compared to only 32 percent of patients with a CTC count of less than five.
"A CTC count of five or greater at the time of restaging was associated with a 5.2 fold increase in a patient's chance of having disease progression compared to CTC counts of less than five," explained Dr. Liu.
"So far the good news is that my number has always been zero or one," said Anne Crupi. "And it's so easy. All they do is take a small tube of blood."
Additional data suggest that the CTC assay is a more reliable means of assessing treatment response than other traditional serum based tumor markers currently in use. Currently, Dr. Liu serves at the national principal investigator of a clinical study that will evaluate the CTC results within the framework of a randomized clinical trial – eliminating possible variability caused by treatments administered.
"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," Dr. Liu concluded.
Media Contact: Marianne Worley
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