Colorectal Cancer

Diagnosis

The physician will perform a physical examination for any signs or symptoms of colorectal cancer. Some screening guidelines are used to detect polyps, cancer, or other abnormalities in the colon and rectum. These include:

Fecal occult blood test (FOBT):
FOBT examines the stool for blood not easily noticed by the naked eye. In this test a small amount of stool is placed on a special paper and the physician applies a chemical to it to see if blood is present in the stool sample. If it detects blood, other tests are needed to find the source of the blood.

Sigmoidoscopy: 
Sigmoidoscopy is a procedure to detect polyps using sigmoidoscope which is a long, flexible instrument about 1/2 inch in diameter. The physician can view the lining of the rectum and lower (sigmoid) colon through sigmoidoscope. If polyps are found, it is removed and the procedure is called polypectomy.

Colonoscopy:
It is an endoscopic test. The rectum and the inside of the entire colon are examined in colonoscopy, using a long, flexible tube with a tiny camera on the end called colonoscope. If polyps are found, it is removed.

Air contrast barium enema or Double-contrast barium enema (DCBE):
This is a series of X-ray examination of the entire colon and rectum. Before the x-ray is taken, the patient is given an enema with a barium solution. Barium is a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up solid on x-rays. The liquid is introduced into the colon and rectum through the anus. The liquid contains barium, which shows up solid on x-rays. Air is pumped gradually into the colon by a rectal tube to improve visualization. The barium and air outline the colon and rectum on the x-rays. Polyps may show up on the x-ray. 

Digital Rectal Exam (DRE): 
It is a part of the routine physical examination. The doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas in the lower part of the rectum. If an abnormality is detected by a digital rectal examination, then an endoscopy is performed for further evaluation of the cancer.

After initial diagnostic tests, if colorectal cancer is suspected, a biopsy, removal of cells or tissues, is performed by a pathologist. If cancer cells are detected in biopsy, further tests are recommended to know the extent (stage) of the disease. These may include: 

Blood test for CEA: 
Carcinoembryonic antigen (CEA) is a protein normally found in trace amounts in the bloodstream. People who have colorectal cancer or other conditions or who smoke have a high CEA level. CEA is referred to as a tumor marker.

Endoscopic Ultrasound (EUS) or Endorectal ultrasound : 
An endoscopic ultrasound is used to detect the depth of the cancer growth. An ultrasound probe at the tip of an endoscope is inserted into the rectum. The probe sends out sound waves that people cannot hear. The waves bounce off the rectum and nearby tissues, and a computer uses the echoes to create a picture. The picture shows how deep a rectal tumor has grown or whether the cancer has spread to lymph nodes or other nearby tissues.

Chest x-ray: 
X-rays of the chest can show whether cancer has spread to the lungs.

CT scan: 
An x-ray machine linked to a computer takes a series of detailed pictures of areas inside the body. The patient may receive an injection of dye. Tumors in the liver, lungs, or elsewhere in the body show up on the CT scan.