Do I need chemotherapy after my surgery?

This is a typical question that patients like you ask their doctors after they have been diagnosed with colorectal cancer and had their tumor removed by surgery.  Many of them are afraid to experience colorectal cancer recurrence and they want the best treatment possible.

To answer this question and decide about a potential adjuvant chemotherapy, your physician will ask the hospital pathologist to examine your tumor and your lymph nodes that were removed during your colorectal cancer surgery, in order to establish the stage of your cancer.

Staging of your cancer

Staging is one way physicians classify cancer. Criteria include the size of your tumor and whether it has spread to the lymph nodes surrounding your tumor. Staging is one of the most important tools physicians have in determining a patient’s prognosis or risk of colorectal cancer recurrence, and the type of treatment a patient should receive.

In assessing the stage of your cancer, the pathologist will examine thin slices of tissue from each of your lymph nodes removed during your surgery (usually 12 nodes or more), using a microscope. If cancer cell clusters are not found in your lymph nodes, the cancer will be classified as stage I or II. Most patients with stage I or II disease are considered cured or at low risk for disease recurrence and do not receive chemotherapy.

Unfortunately, up to 30% of them experience a recurrence of their cancer, presumably through cancer cells that were missed using the microscope method, which results in an underestimation of the risk of recurrence. In comparison, most stage III patients, that is, those where cancer cells were found in their lymph nodes as seen under the microscope, receive chemotherapy.

If I am stage I or II, am I one of those 30% who will have a disease recurrence?

This is a very difficult yet critical question to answer. Fortunately, with research on the human genome and molecular technologies, it is now possible to detect with 100,000 times more sensitivity cancer cells in your lymph nodes and hence better assess your risk of recurrence. This is exactly what the Previstage™ GCC Colorectal Cancer Test does. The test detects the presence or absence of GCC gene activity in your lymph nodes removed during the surgery. GCC (GUCY2C) is normally found exclusively in colon cells, both normal and cancerous. So when it is detected in the lymph nodes, it is an indication that the cancer has spread, and you and your doctor may decide on an additional treatment such as chemotherapy to increase your chances of survival. On the other hand, if GCC is absent in your lymph nodes, it indicates that there is lower risk that your cancer has spread, and you and your doctor may decide not to risk the negative impact of chemotherapy.

What do scientists know about GCC (GUCY2C)?

The relation between GCC (guanylyl cyclase C) and colorectal cancer was discovered in the early 1990’s by Dr. Scott Waldman at Thomas Jefferson University. In 2008, Dr. Waldman concluded a 5-year multicenter clinical study sponsored by the U.S. National Institutes of Health on the detection of GCC in lymph nodes to assess the risk of rectal and colon cancer recurrence in patients. His results strongly support the prognostic value of GCC testing and show that patients with GCC positive lymph nodes are 4.7 times more likely to develop disease recurrence than GCC negative patients. The study was published in the Journal of the American Medical Association in February 2009.

In an educational session held during the 2009 Gastrointestinal Cancers Symposium (ASCO GI) which reviewed different markers for colorectal cancer prognosis, it was suggested that patients with GCC positive lymph nodes could be considered as stage III patients. To the presentation >>

DiagnoCure Oncology Laboratories is a CLIA-certified service laboratory that developed, validated and performs the Previstage™ GCC Colorectal Cancer Staging Test, which detects the presence or absence of GCC activity in the lymph nodes. For more information on the test, click here.