Description: The colon and rectum are parts of the body's digestive system, which removes nutrients from food and stores waste until it passes out of the body. Together, the colon and rectum form a long tube called the large intestine. The colon is the first 6 feet of the large intestine and the rectum is the last 8 to 10 inches. Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancers affecting either of these organs may also be called colorectal cancer.

Possible Causes: Exact causes of colorectal cancer are not known, however the following risk factors increase a person's chances of developing colorectal cancer:

• Colorectal cancer is more likely in people over 50, but nonetheless can occur those of younger ages
• Colorectal cancer is more likely to occur in those with diets that are high in fat and calories and low in fiber.
• Polyps which are benign growths on the inner wall of the colon and rectum can increase a person's risk. Familial polyposis, an inherited condition, is almost certain to lead to colorectal cancer.
• Women with a history of cancer of the ovary, uterus, or breast have an increased chance of developing colorectal cancer, as does a person who has already had colorectal cancer before.
• First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves.
• Ulcerative colitis is a condition in which the lining of the colon becomes inflamed, increasing a person's chance of developing colorectal cancer.

Symptoms: Common signs and symptoms of colorectal cancer include:

• A change in bowel habits
• Diarrhea, constipation, or feeling that the bowel does not empty completely
• Blood (bright red or very dark) in the stool
• Stools that are narrower than usual
• General abdominal discomfort such as frequent gas pains, bloating, fullness, and/or cramps
• Weight loss
• Constant tiredness
• Vomiting

Diagnoses: Tests are used to detect polyps, cancer, or other abnormalities, even when a person does not have symptoms.

• A Fecal occult blood test (FOBT) is a test used to check for hidden blood in the stool. Sometimes cancers or polyps can bleed, and FOBT is used to detect small amounts of bleeding.
• A sigmoidoscopy is an examination of the rectum and lower colon (sigmoid colon) using a lighted instrument called a sigmoidoscope.
• A colonscopy is an examination of the rectum and entire colon using a lighted instrument called a colonscope.
• A double contrast barium enema (DCBE) is a series of x-rays of the colon and rectum. The patient is given an enema with a solution that contains barium, which outlines the colon and rectum on the x-rays.
• A digital rectal exam (DRE) is an exam in which the doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas.
• A biopsy is the removal of a tissue sample for examination under a microscope by a pathologist to make a diagnosis.

Stages: 

• Stage 0: The cancer is very early. It is found only in the innermost lining of the colon or rectum.
• Stage 1: The cancer involves more of the inner wall of the colon or rectum.
• Stage II: The cancer has spread outside the colon or rectum to nearby tissue, but not to the lymph nodes.
• Stage III: The cancer has spread to nearby lymph nodes, but not to other parts of the body.
• Stage IV: The cancer has spread to other parts of the body. Colorectal cancer tends to spread to the liver and/or lungs.