Colon and Rectal Cancer Work-up (Evaluation)

If there is reason to suspect that you have colon or rectal cancer, the doctor will take a complete medical history and do a physical exam. Also, one or more of the following tests will be done to find out if the disease is really present and to determine its stage (how far the cancer has spread).

Medical history and physical exam: When your doctor “takes a history,” he or she will ask you a series of questions about your symptoms and risk factors. Some colorectal cancers may be found because of symptoms such as a change in bowel habits, blood in the stool, weakness or fatigue, abdominal pain, loss of appetite, nausea, weight loss, and straining during a bowel movement. Of course, many noncancerous conditions and some other cancers can cause one or more of these symptoms. But if these symptoms are present, a medical evaluation is the only way to determine their cause so that the most appropriate treatment can be chosen. A physical exam for patients thought to have colorectal cancer will include a digital rectal examination (DRE), careful examination of the abdomen to feel for masses or enlarged organs, and a general survey of the rest of the body.

Colonoscopy: A colonoscope is a long, flexible, lighted tube about the thickness of a finger. It is inserted through the rectum up into the colon. A colonoscope is longer than a sigmoidoscope and allows the doctor, in most cases, to see the entire colon lining. The colonoscope is connected to a video camera and video display monitor so that the doctor can look closely at the inside of your colon. Before this test, you will take strong laxatives to cleanse your bowel and on the morning of the test you will also take an enema. Colonoscopy lasts about 15 to 30 minutes and is generally not painful because a mild sedative is given.

Biopsy: If a mass or any other abnormal areas are seen through the flexible sigmoidoscope or through the colonoscope, a sample will be taken. A pathologist will examine the sample under a microscope to determine whether it is a cancer or some benign condition. Some abnormalities, such as small polyps, may be entirely removed through a colonoscope. If the abnormal area is large, a biopsy (small tissue sample) is taken. The biopsy sample is usually about 1/8-inch across and is removed with instruments that are used through the scope.

If you have questions about pathology results or any other aspect of the diagnostic process, do not hesitate to ask your doctor. You can obtain a pathology review by having microscope slides containing thin slices of your specimen sent to a consulting pathologist at an NCCN cancer center or other laboratory recommended by your doctor.

Blood counts and blood chemistry: Your doctor will order a blood test that will determine if you are anemic. Many people with colorectal cancer become anemic because of bleeding from the tumor. A blood test will also show how your liver is functioning. Colorectal cancer can spread to the liver and cause changes in blood proteins and enzymes.

Tumor markers: Colon and rectal cancers produce substances such as carcinoembryonic antigen (CEA) and CA 19-9 that are released into the bloodstream. Blood tests for these “tumor markers” are used most often with other tests to watch patients who already have been treated for colorectal cancer. They may provide an early warning that a cancer has returned.

Because the CEA level in the blood can be high for reasons other than cancer or may be normal in a person who has cancer, it is not used to find cancer in people who have never had cancer and appear to be healthy.

Chest x-ray: This familiar imaging test can often detect the spread of colorectal cancer to the lungs.

Ultrasound: This imaging test uses a device called a transducer that produces sound waves, which are reflected by nearby body tissues and organs. The pattern of sound wave echoes is detected by the transducer and analyzed by a computer to create an image of the area being studied. Since normal body tissues and tumors reflect sound waves differently, ultrasound is sometimes used to find masses that indicate local or distant spread of cancer. Two special types of ultrasound examinations are used to evaluate people with colon and rectal cancer. Endorectal ultrasound uses a special transducer that can be inserted into the rectum. This test is used to see how far a rectal cancer may have grown and whether it has spread to nearby organs or tissues. Intraoperative ultrasound is done after the surgeon has opened the abdominal cavity. The transducer can be placed against the surface of the liver, making this test very useful in detecting metastases of colorectal cancer to the liver.

Computed tomography: Commonly referred to as CT or a CAT scan, this test uses a rotating x-ray beam to create a series of pictures of the body from many angles. A computer combines the information from these pictures, producing a detailed cross-sectional image. Contrast material is usually injected into a vein before CT scanning to help produce clearer pictures. A CT scan can often detect the spread of colorectal cancer to internal organs such as the liver, lungs, or elsewhere in the abdomen. Spiral CT uses a special scanner that can provide greater detail and is sometimes useful in finding metastases from colorectal cancer. For a spiral CT with portography, contrast material is injected into veins that lead to the liver, to help find metastases from colorectal cancer to that organ.

CT-guided needle biopsy: If a metastasis is discovered, this test is often done. For this test, the patient remains on the CT scanning table while a radiologist places a biopsy needle in the mass. CT scans are repeated until the doctors are confident that the needle is within the mass. A fine needle biopsy sample (tiny fragment of tissue) or a core needle biopsy sample (a thin cylinder of tissue about 1/2-inch long and less than 1/8 -inch in diameter) is removed and examined under a microscope.

Magnetic resonance imaging: Like computed tomography, magnetic resonance imaging (MRI or an MRI scan) displays a cross-section of the body. However, MRI uses powerful magnetic fields instead of radiation. The procedure can show cross-sectional views from several angles and is useful in locating metastases from colorectal cancer that are sometimes hard to see on standard x-rays and CT scans. A special MRI can show the doctor more about rectal tumors.

Positron emission tomography: Positron emission tomography (PET or a PET scan) uses glucose (a form of sugar) that contains a radioactive atom. The cancer cells will absorb the glucose and can be detected by a scanner. PET is often useful in identifying cancers that have spread and is used in patients with a rising CEA or suggested metastatic disease by other tests.

Angiography: For this test, a catheter (thin tube) is placed in a blood vessel and moved until it reaches the area to be studied. Contrast dye is injected rapidly, and a series of x-ray images is then taken. When the pictures are complete, the catheter is removed. Angiography is sometimes used to show surgeons the location of blood vessels next to a liver metastasis from colorectal cancer so that an operation can be planned.

INTRODUCTION

COLON AND RECTAL CANCER STAGES

For more information on these treatment guidelines, or on cancer in general, call the NCCN at 1-888-909-NCCN or the American Cancer Society at 1-800-ACS-2345. Or you can visit these organizations’ web sites at www.cancer.org (ACS) and www.nccn.org (NCCN).

© 2005 by the National Comprehensive Cancer Network (NCCN) and the American Cancer Society (ACS). All rights reserved. The information herein may not be reproduced in any form for commercial purposes or downloaded and stored in any information-retrieval system without the express written permission of the NCCN and the ACS. Single copies of each page may be printed out for personal, noncommercial use only.