Understanding the Results of the Previstage™ GCC Colorectal Cancer Staging Test

When your doctor prescribes the Previstage™ GCC Colorectal Cancer Staging Test, he or she wants to find out if you have colorectal cancer metastases in the lymph nodes that were removed during your surgery. The presence or absence of colorectal cancer cells in your lymph nodes gives an indication of your risk of experiencing a recurrence of your cancer, since people who have colorectal cancer cells in their lymph nodes have an overall higher risk of recurrence than those who don’t. This relationship is factored into the current system for determining the stage of your cancer. (See Understanding Staging for more details about lymph nodes and their role in determining your prognosis.)

Previstage™ GCC uses state-of-the-art genomic technologies to identify cancer cells in your lymph nodes that have been missed by the initial microscopic examination. During the initial microscopic test, a pathologist looks at the shape of cells in one or more thin slices of each lymph node, which represents only about 1% of the lymph node mass. In addition, the detection capacity is limited by the microscope. The microscope can detect one cancer cell in 200 normal cells, while genomic technologies can detect one cancer cell in 10 million normal cells. Moreover, with Previstage GCC, at least half of each lymph node is examined for the presence or absence of the GCC biomarker. (GCC is normally only found in the cells lining the intestine, so it is an excellent predictor of the spread of cancer cells when it is found in the lymph nodes, where it would not normally be.)

Results interpretation

Your patient report will indicate how many of your lymph nodes tested are GCC positive, GCC negative or uninterpretable.

GCC (GUCY2C) positive lymph node: When a lymph node is called “positive,” it means that the GCC marker was detected, indicating the presence of colorectal cancer cells in the lymph node. The presence of colorectal cancer cells in one or more of your lymph nodes is usually an indication of a higher risk of recurrence of your cancer. In this circumstance, your doctor may recommend additional treatment, such as chemotherapy, to improve your chances of not recurring.

GCC (GUCY2C) negative lymph node: When a lymph node is “negative,” it means that the GCC marker was NOT detected, which indicates that the test did not find colorectal cancer cells in the section of the node that was tested. If all of your lymph nodes tested are GCC negative, you normally have a lower risk of recurrence. In this circumstance, your doctor may suggest that additional treatment  is not necessary.

Uninterpretable lymph node: Although not common, occasionally the tissues of some of your lymph nodes have deteriorated, and it becomes impossible to process these lymph nodes to identify the presence or absence of the GCC marker. When this happens, the lymph node is called “uninterpretable.”

The Previstage™ GCC Colorectal Cancer Staging Test is a laboratory-developed test. It was developed and its characteristics were determined by DiagnoCure Oncology Laboratories.