Minetta Liu, MD, Breast Cancer Specialist, Mayo Clinic, Rochester, Minnesota, describes the CellSearch CTC Test in patients with breast cancer.

The CellSearch Circulating Tumor Cell (CTC) Test is the only technology cleared by the FDA. In order to be cleared by the FDA, Liu says, the CellSearch test met metrics for being reproducible and user-friendly.

From a single tube of the patient's blood, the number of CTCs are counted in an automated and reproducible way. The number of CTCs can be anywhere from zero to tens or hundreds of thousands, Liu says, though the absolute number is not what matters. Patients with fewer than five CTCs have a favorable prognosis, while greater than or equal to five is unfavorable. The CellSearch test allows for an assessment of patient prognosis and is predictive of progression-free survival and overall survival.

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Minetta Liu, MD, Breast Cancer Specialist, Mayo Clinic, Rochester, Minnesota, describes the CellSearch CTC Test in breast cancer.

Dr. Liu Describes the CellSearch CTC Test

Minetta Liu, MD, breast cancer specialist, Mayo Clinic, Rochester, Minnesota, discusses the limitations of radiology in metastatic breast cancer treatment.

Liu says that the key in metastatic breast cancer is trying to stay ahead and determine the right time to change therapy. Currently, the gold standard for measuring this is by using imaging such as CAT scans, MRIs and ultrasounds.

However, Liu says, it is difficult for a radiologist to measure these tumors in a reproducible way. A study found a variability of 15% when radiologists were asked to look at two identical images and report if the patient progressed. Liu says that the variation can be higher if it’s the same radiologists looking at the same pictures a week later.

Liu says that a better, more reliable method must be determined. Counting circulating tumor cells (CTCs) are more reliable and reproducible and the variation is only on the order of 1-5%.

Although no test is perfect, having multiple, reliable tools would help physicians to measure the progression of metastatic breast cancer, Liu says.

Dr. Liu on the Limitations of Radiology in Breast Cancer

Minetta Liu, MD, Breast Cancer Specialist, Mayo Clinic, Rochester, Minnesota, discusses the use of circulating tumor cells (CTCs) for prognosis and prediction in patients with breast cancer.

Currently, research is focused on using CTCs in patients with metastatic disease, with the goal being to have a better means of prognosis and prediction. A patient's prognosis relates to the biology of the tumor and is an evaluation of whether or not they will do well. Conversely, a prediction tries to inform a patient and physician about the efficacy of drugs. In different patients, CTCs can provide information in terms of a drug's efficacy or if the disease will progress without the need to change treatment. A third possibility is that the disease is so aggressive that a conventional treatment will not work.

Liu says that scans help follow patients, but are only conducted every 3-4 months, which is sometimes too infrequent. There is a need for an efficient way to determine whether the most appropriate treatment is being administered.

Minetta Liu, MD

Articles

Dr. Liu Describes the CellSearch CTC Test

Dr. Liu on the Limitations of Radiology in Breast Cancer

Dr. Minetta Liu on CTCs for Prognosis and Prediction