Blood Test Assesses Treatment Efficacy for Metastatic Breast Cancer

Scientists who aim to tailor cancer treatment for individual patients have used a simple blood test to assess treatment efficacy for patients with metastatic breast cancer.

Using CellSearch technology, the scientists measured the number of circulating tumor cells (CTCs) in blood collected from women with metastatic breast cancer. About 10 ml of blood was collected every three to four weeks. The number of CTCs was correlated with disease response or progression as determined by standard radiology studies performed every 9-12 weeks. The women in the study received various treatments including chemotherapy, endocrine therapy, and combination therapy with a biologic agent.
The CellSearch technology was developed by Veridex LLC (Warren, NJ, USA).

A CTC count of five was used as the threshold, based on previous studies. There was a highly significant difference in the distribution of progression between two groups of patients defined by their CTC result. Seventy-one percent of patients who had a CTC greater than or equal to five had disease progression, and 66% of patients with a CTC count of less than five did not.

The study was performed at Georgetown University Medical Center (GUMC; Washington, DC, USA) and the investigators concluded that circulating tumor cells are a reliable predictor of treatment response in 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 Minetta Liu, M.D., of Georgetown's Lombardi Comprehensive Cancer Center (Washington, DC, USA). "Right now, we have to rely on radiology studies such as CT [computed tomography] 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.”

Dr. Liu added that the CTC assay is a more reliable means of assessing treatment response than the traditional tumor markers currently in use.


Related Links:
Georgetown University Medical Center
Lombardi Comprehensive Cancer Center