Colorectal Cancer

The doctors diagnose the cancer and determine what kind it is by looking at a sample of the tumor under a microscope. This alone does not determine what treatment you can have. Before treatment, your doctors must determine if or how much the colon or rectum cancer has spread. This is called staging the cancer.

In colon cancer, staging reflects how far into the colon the tumor has grown and whether or not it has spread beyond it, either to the lymph nodes or to distant organs. Earlier stage may be curable; however, in most cases cancer that has spread to other organs is incurable, once again highlighting the importance of early detection.

The outlook for your recovery and your treatment options, which may include surgery, radiation therapy or chemotherapy, depend upon the stage of the cancer. For early cancer, surgery may be all that is needed. For cancer that is more advanced, chemical or radiation therapy may be needed as well to increase the chance of a cure or delay the cancer's progression.

PET is the most useful test that you can have when doctors are staging or re-staging colon or rectal cancer because it is more accurate than CT or any other test.

How PET works: In cancer, cells begin to grow at a much faster rate, feeding on sugars like glucose. PET works by using a small amount of a radioactive drug called a tracer in combination with a compound such as glucose. Once you are injected with the tracer and glucose, the tracer travels through your body. It emits signals as it travels and eventually collects in the organs targeted for examination. If an area in an organ is cancerous, the signals will be stronger since more glucose will be absorbed in those areas.

In colon cancer, if the lymph nodes near the tumor or if a distant organ such as the liver has become involved by the cancer, they will take up more of the radioactive glucose. Whether or not distant organs are involved is a critical factor in deciding what your surgical and medical treatment will be. Some studies have shown that even if the cancer is spread in a limited way outside the colon, surgery can be done to remove these other tumors and improve your chance of recovery. CT scans may over or under-estimate the number of tumors in the liver, making it an unreliable test to identify patients that might benefit from aggressive surgical intervention. In the same whole-body picture, the PET scan can look throughout your whole body to see if there are any clumps of the cancer cells that have spread. The PET scan can make the difference in determining whether surgery should be done as well as chemotherapy or radiation therapy. After first showing the doctors where the cancer cells are, PET can also see if the chemotherapy and/or radiation therapy has been effective in killing them.