Types of Cancer > Colorectal Cancer > Diagnosis

Colorectal Cancer Diagnosis

More than 95 percent of colorectal cancers are adenocarcinomas or cancers of the cells that line the interior of the colon and rectum. If tests indicate the presence of colorectal cancer, additional examinations are performed to determine the extent or stage of the disease based on how deep the cancer has penetrated the various tissue layers.

Imaging Tests
Radiological tools used to diagnose and stage colorectal cancer include computed tomography, magnetic resonance imaging, chest x-ray, positron-emission testing scanning and ultrasound. For a complete list of imaging resources available at Greenwich Hospital, see the Radiology Services section of this web site.

Biopsy
A biopsy involves the removal of a small amount of tissue (either during a colonoscopy or surgery), which a pathologist examines under a microscope to determine the presence of cancer cells.

Blood Tests
Blood tests are performed to check for the presence of CEA, a protein that acts as a marker for colorectal cancer. The CEA test is often used to diagnose a possible recurrence in people who have had colorectal cancer in the past. The CEA test does not diagnose early colon cancer and is not a substitute for colonoscopy.

Angiography
Physicians may perform an angiography to find blood vessels next to cancer that has spread to the liver. This information allows them to plan surgery that minimizes blood loss.