Cancer from A to Z

Many factors may influence the development of colon cancer, including:

• Age: Colon cancer is most common in people over 50.
• Family history: Your risk is higher with a family history (especially parent, sibling) of colon cancer or adenomatous polyps.
• Personal history: Your risk is higher with a personal history of inflammatory bowel disease (Crohn’s disease or colitis), colon canceror adenomatous polyps.
• Weight: Lack of physical activity and obesity are risk factors.
• Diet: A high-fat diet, particularly animal fats, may increase your risk. Diets high in fruits and vegetables are thought to decrease your risk.
• Cigarette smoking and alcohol: Your risk may be higher if you smoke or drink alcohol.

Reducing Your Risk
You can take action to reduce your risk of developing colon cancer by:

• Eating at least five servings of fruits and vegetables per day
• Limiting your fat intake to no more than 30% of your total daily calories
• Exercising regularly
• Maintaining your ideal weight
• Quitting smoking
• Limiting alcohol consumption

Screening Guidelines
Cancer screenings are medical tests that are performed when a person has no symptoms. Starting at age 50, men and women should follow one of the five examination schedules below. All positive tests (FOBT, FIT, flexible sigmoidoscopy, barium enema) should be followed up with a colonoscopy.

Colonoscopy: Every 10 years (preferred by MD Anderson).
Fecal occult blood test (FOBT) or fecal immunochemical test (FIT): Every year. Both tests are available in take-home versions.
Flexible sigmoidoscopy: Every five years.
Annual FOBT or FIT and flexible sigmoidoscopy: Every five years. Having both tests is recommended over either test alone.
Double-contrast barium enema: Every five years.
People at moderate or high risk for colon cancer (e.g., strong family history) should talk with their doctor about the need for a different testing schedule.

These screening guidelines are provided as a guide. If results of these exams suggest cancer, more extensive diagnostic tests of the colon or rectum should be conducted. More frequent exams are needed if polyps (precancerous lesions) are found. In individuals at increased risk with a family history of colon cancer or polyps or a personal history of inflammatory bowel disease, screening may need to begin earlier.

There are many methods for diagnosing colon cancer. Some of these procedures are also used as screening devices to detect colon cancers in the early stages, when treatment is more successful.

Fecal Occult Blood Test (FOBT): A stool sample is examined for traces of blood not visible to the naked eye. If you do see blood in your stool, contact your doctor immediately.

Fecal Immunochemical Test (FIT): FIT is a take-home test that detects blood proteins in stool. A small, long-handled brush is used to collect a stool sample, which is placed on a test card and sent to a lab for examination.

Sigmoidoscopy: A tiny camera with flexible plastic tubing is inserted into the rectum, providing a view of the rectum and lower colon. This procedure can also be used to remove suspicious tissue for examination.

Colonoscopy: A colonoscope is a longer version of a sigmoidoscope, and can examine the entire colon. Patients must be sedated for a colonoscopy.

Virtual colonoscopy: Instead of a scope, physicians use imaging technology to view the colon. Air is pumped into the colon to expand it for better imaging. Virtual colonoscopy can be performed with computed tomography (CT) or magnetic resonance imaging (MRI).

Double Contrast Barium Enema (DCBE): Barium is a chemical that allows the bowel lining to show up on X-ray. A barium solution is administered by enema; then the patient undergoes a series of X-rays.

Digital Rectal Exam: The doctor inserts a gloved finger into the rectum to feel for polyps or other irregularities.

Carcinoembryonic Antigen (CEA): A blood test that determines the presence of CEA, a substance, or tumor marker, produced by some cancerous tumors. This test can also be used to measure tumor growth or assess if cancer has recurred after treatment.

Staging
Stage 0: Abnormal cells are found in the innermost lining of the colon or rectum. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Stage I: Cancer has formed and spread beyond the innermost tissue layer of the colon or rectum wall to the middle layers. Stage I colon cancer is sometimes called Dukes A colon cancer.

Stage II: Colon cancer is divided into stage IIA and stage IIB. Stage II colon cancer is sometimes called Dukes B colon cancer.

Stage IIA: Cancer has spread beyond the middle tissue layers of the colon or rectum wall or has spread to nearby tissues around the colon or rectum
Stage IIB: Cancer has spread beyond the colon or rectum wall into nearby organs and/or through the peritoneum
Stage III: Colon cancer is divided into stage IIIA, stage IIIB and stage IIIC. Stage III colon cancer is sometimes called Dukes C colon cancer.

Stage IIIA: Cancer has spread from the innermost tissue layer of the colon or rectum wall to the middle layers and has spread to as many as three lymph nodes
Stage IIIB: Cancer has spread to as many as three nearby lymph nodes and has spread:beyond the middle tissue layers of the colon or rectum wall
to nearby tissues around the colon or rectum
beyond the colon or rectum wall into nearby organs and/or through the peritoneum
Stage IIIC: Cancer has spread to four or more nearby lymph nodes and has spread:
to or beyond the middle tissue layers of the colon or rectum wall
to nearby tissues around the colon or rectum
to nearby organs and/or through the peritoneum.
Stage IV: Cancer may have spread to nearby lymph nodes and has spread to other parts of the body, such as the liver or lungs. Stage IV colon cancer is sometimes called Dukes D colon cancer.

Surgery
Surgery is the most common treatment for colon and rectal cancers. Depending on the stage and location of the tumor, different surgical methods are used.

Local excision: If tumors are small enough, they may be removed with minimally invasive surgery. Tiny incisions are made in the abdomen. A miniature camera and surgical instruments are inserted. The surgeon uses computer imaging to locate and remove the tumor.

Polypectomy: Suspicious or cancerous polyps on the colon wall can easily be removed. A colonoscope is a long tube with a camera in the end. The colonoscope is inserted in the rectum and guided to the area requiring treatment, and a tiny, scissor-like instrument removes the polyp.

Colectomy: Surgeons remove the cancerous portion of the colon, along with a margin of healthy tissue on either side, and then join the colon back together. This procedure is also called a hemicolectomy or segmental resection.

Resection & colostomy: If the colon cannot be rejoined after removing the cancer, surgeons will perform a colostomy. A stoma (hole) is cut in the abdominal wall and attached to a segment of colon. Bodily waste goes through the stoma into a plastic bag outside the body. Colostomies may be temporary, allowing the bowel to heal before resection. However, about 15% of colostomies are permanent.

Radiation Therapy
Radiation therapy may be used to destroy any colon or rectal cancer cells that remain after surgery. Radiation is used most often on rectal cancers, or those that cannot be treated with surgery. It can also be used to relieve cancer symptoms.

The following technological means and radiation therapy are used with this disease:

• Virtual CT simulation
• Intensity modulated radiation therapy (IMRT)
• Volumetric modulated arc therapy (VMAT)
• Stereotactic body radiation therapy (SBRT)

Chemotherapy

Chemotherapy can be used to shrink rectal tumors before surgery, or to lengthen survival time after surgery. Chemotherapy is generally not effective for advanced or recurring colon cancers.

Targeted Therapy
Researchers are developing new drugs that are designed to seek out and destroy specific types of cancer cells without affecting healthy cells.