Breast Cancer Test

By Jennifer Abney Anchor

A new test is checking the blood to see if breast cancer therapy is working. Breast Cancer Test

Published: Fri, September 12, 2008 - 4:10 am

Jennifer Abney

This year, the American Cancer Society estimates more than 1.4 million new cases of cancer will be diagnosed in the U.S. The most commonly diagnosed cancers are breast, prostate, lung and colorectal cancers. About 565,650 Americans are expected to die of cancer in 2008.

When cancer occurs, the original location of the tumor is called the primary site. However, cells can break away from the primary site and get into the bloodstream or lymphatic system, where they travel to other areas of the body and start to grow. This new tumor site is a metastasis and the disease is called metastatic cancer. Cancer that spreads to nearby lymph nodes is called a regional spread. If the cancer spreads to areas far away from the original site, it is defined as distant spread. Distant metastases are typically defined as stage IV cancer.

A metastasis can be differentiated from a primary tumor because it maintains the characteristics of the primary tumor. For example, a breast cancer metastasis found in a lung will still look like breast cancer, not lung cancer. In some cases, patients may not have any symptoms of cancer until the disease has spread and causes symptoms related to the location of metastasis. A brain metastasis can cause seizures, headaches and balance problems. Bone metastasis can cause pain and fractures.

Monitoring Patients with Metastatic Cancer
When a tumor metastasizes, it can be difficult to find a treatment that works. Often the cancer becomes resistant to common therapies. And, because the cancer has spread, doctors need to treat more than one site, which sometimes limits options. Depending on the type of cancer, the size and location of the metastasis and the patient’s health, treatment may include surgery, chemotherapy, radiation therapy, hormone therapy, biological therapy and/or cryotherapy. Often doctors will use a combination of treatments to attack the cancer.

Traditionally, doctors use physical exam, lab tests and diagnostic imaging scans to determine how a patient is responding to a treatment. If the tumor(s) appears to be shrinking, they know they are on the right track and will continue the therapy. But if the tumor is growing, then a more aggressive approach or change in direction is needed.

CellSearch™
Another method of monitoring treatment progress is by measuring the number of tumor cells circulating in the blood. It’s a daunting task – there are more than 40 billion cells in a single vial of blood. But a technology, called CellSearch™ Circulating Tumor Cell Test, is automating the process. The technology is so sensitive it can identify a single circulating tumor cell in a blood sample.

CellSearch has two components – the CellSearch Epithelial Cell Kit and the CellSpotter™ Analyzer. First, a sample of blood from the patient is treated with the CellSearch Epithelial Kit. The kit contains tiny, protein-coated magnetic balls that adhere to the circulating tumor cells. The identified cells are stained and placed on a special cartridge. Next, a magnetic field is applied to the cartridge, which pulls the magnetized tumor cells to the surface. Finally, the cartridge is analyzed by the CellSpotter Analyzer, which counts the cancer cells.

The CellSearch system is FDA approved for monitoring metastatic breast, prostate and colorectal cancers. The cutoff numbers for circulating tumor cells are 5 for metastatic breast and prostate cancer and 3 for metastatic colorectal cancer. Patients with a circulating tumor cell test below the cutoff value are more likely to have a better prognosis. On the other hand, having a greater number of circulating tumor cells may mean the tumor is growing and current treatments are ineffective.

Minetta Liu, M.D., a Breast Oncologist at Lombardi Comprehensive Cancer Center/Georgetown University Medical Center, says with traditional tumor monitoring techniques, doctors often can’t see any changes in tumor progression or regression until at least a month after treatment has started. If the patient isn’t responding to the treatment, that could mean lost time. By using the CellSearch system, doctors can find out if a treatment is working within a few hours.

Liu says CellSearch is meant to be used in conjunction with standard monitoring techniques. The test can be done at the start of treatment to decide the best initial approach for the patient and then used periodically to assess the patient’s progress. The National Cancer Institute is currently studying the efficacy of using circulating tumor cells in treatment decisions for women with metastatic breast cancer. For more information, go to http://www.clinicaltrials.gov. Then type the trial identification number in the search box: NCT00382018.

AUDIENCE INQUIRY
For information about the CellSearch™ System: Veridex LLC, http://www.veridex.com

The National Cancer Institute is studying the use of circulating tumor cells in treatment decisions for women with metastatic breast cancer. For more information, go to http://www.clinicaltrials.gov. Then type the trial identification number in the search box: NCT00382018.

For information on metastatic cancer: American Cancer Society, http://www.cancer.org
National Cancer Institute, http://www.cancer.gov