Colon Cancer

Colon cancer and rectal cancer sometimes are grouped together and called colorectal cancer. Not counting skin cancers, colorectal cancers are the third most common type of cancer in the United States. More than 106,000 people in this country are diagnosed with colon cancer each year, according to the American Cancer Society.

One in 19 people, or a little more than 5%, of Americans will develop colon or rectal cancer in their lifetimes. When colon cancer is diagnosed early, it has nearly a 90% chance for cure.

The colon is part of the digestive system, also called the gastrointestinal (GI) tract.

• The colon is the first six feet of the large intestine, also called the large bowel
• The rectum is the last six inches of the large intestine, which ends in the anus

Colorectal cancers grow slowly. They usually start as polyps, which are overgrowths of tissue in the lining of the colon. Colon cancer may start within a polyp, but not all polyps contain cancer.

Colon cancer survival rates have increased over the past 15 years. Because of screening, polyps often are found and removed before they become cancer. Also, treatments have become more advanced and less invasive.

Types of Colon Cancer

More than 95% of colorectal cancers are adenocarcinomas. Approximately 90% of colorectal adenocarcinomas began as adenomas, which are a type of polyp that may become cancer.

About 20% of colon cancers are inherited or are associated with a strong history of colon cancer in the family. The main types of colon cancer that are inherited include:

Hereditary nonpolyposis colorectal cancer syndrome or HNPCC (also called Lynch syndrome), accounts for 5% to 7% of colon cancers.

Familial adenomatous polyposis (FAP) causes hundreds to thousands of polyps in the GI tract. FAP may begin during childhood.

Colon Cancer Risk Factors

Anything that increases your chance of getting colon cancer is a risk factor. Colon cancer risk factors include:

• Family history of colon cancer, rectal cancer or polyps
• Hereditary cancer syndromes such as hereditary nonpolyposis colorectal cancer (HNPCC or Lynch) syndrome or familial adenomatous polyposis (FAP)
• Inflammatory bowel disease (Crohn’s disease or chronic ulcerative colitis)
• Colorectal cancer or polyps
• Obesity
• Lack of exercise
• Diet: If you eat a lot of red meat, processed meats or meats cooked at very high heat, you may be at higher risk for colon cancer
• Diabetes Type 2
• Cigarette smoking
• Drinking too much alcohol

For patients concerned about inherited family syndromes that cause colon cancer, we offer advanced genetic testing to let you know your risk.

Colon Cancer Prevention

Certain lifestyle choices may decrease your chances of getting colon cancer. Try to:

• Have regular screening tests
• Stay at a healthy weight
• Exercise regularly
• Eat a healthy diet with lots of fruits and vegetables
• Avoid cigarettes
• Drink alcohol only in moderation

Visit our prevention and screening section to learn how to manage your colon cancer risk.

Colon cancer often does not have symptoms in the early stages. Most colon cancers begin as polyps, small non-cancerous growths on the colon wall that can grow larger and become cancerous. As polyps or cancers grow, they can bleed or block the intestines.

Symptoms of colon cancer may include:

• Rectal bleeding
• Blood in the stool or toilet after a bowel movement
• Diarrhea or constipation that does not go away
• A change in size or shape of stool
• Discomfort or urge to have a bowel movement when there is no need
• Abdominal pain or a cramping pain in your lower stomach
• Bloating or full feeling
• Change in appetite
• Weight loss without dieting
• Fatigue

These symptoms usually do not mean you have colon cancer. But if you notice one or more of them for more than two weeks, see your doctor.

The following tests may be used to diagnose colon cancer or find out if it has spread. Tests also may be used to find out if surrounding tissues or organs have been damaged by treatment.

Digital rectal exam (DRE): The doctor inserts a gloved finger into the rectum to feel for polyps or other problems.

Fecal occult blood test (FOBT): This take-home test finds blood in stool.

Fecal immunochemical test (FIT): This take-home test finds blood proteins in stool.

Endoscopic tests, which may include:

• Sigmoidoscopy: A tiny camera on flexible plastic tubing (sigmoidoscope) is inserted into the rectum. This gives the doctor a view of the rectum and lower colon. Tissue or polyps can be removed and looked at under a microscope.
• Colonoscopy: A longer version of a sigmoidoscope, a colonscope can look at the entire colon.

Endoscopic ultrasound (EUS): An endoscope is inserted into the rectum. A probe at the end bounces high-energy sound waves (ultrasound) off internal organs to make a picture (sonogram). Also called endosonography.

Imaging tests, which may include:

• CT or CAT (computed axial tomography) scan
• MRI (magnetic resonance imaging) scan
• PET/CT (positron emission tomography) scan
• Virtual colonoscopy or CT (computed tomography) colonoscopy
• Double contrast barium enema (DCBE): Barium is a chemical that allows the bowel lining to show up on an X-ray. A barium solution is given by enema, and then a series of X-rays are taken.

Blood test for carcinoembryonic antigen (CEA): CEA is a protein, or tumor marker, made by some cancerous tumors. This test also can be used to find out if the tumor is growing or has come back after treatment.

Colon Cancer Staging

If you are diagnosed with colon cancer, your doctor will determine the stage of the disease. Staging is a way of classifying cancer by how much disease is in the body and where it has spread when it is diagnosed. This helps the doctor plan the best way to treat the cancer. Once the staging classification is determined, it stays the same even if treatment works or the cancer spreads.

Colon Cancer Stages

(Source: National Cancer Institute)

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

Stage 1: Cancer has formed and spread into the first (submucosa) or second (muscle) layers of the rectal wall. It has not spread outside of the rectum.

Stage 2: Cancer has spread outside of the rectal walls into the surrounding fat or nearby tissue. It has not gone into the lymph nodes.  It is divided into stages IIA, IIB or IIC depending on the extent of local tumor involvement.

Stage 3: Cancer has spread to nearby lymph nodes. It has not spread to other parts of the body.  It is divided into stages IIIA, IIIB or IIIC depending on the extent of local tumor involvement and the number of lymph nodes that contain cancer.

Stage 4: Cancer has spread to other parts of the body, such as the liver, lungs or ovaries. It is divided into stages IVA and IVB depending on the number of different other parts of the body to which the cancer has spread.

Your colon cancer treatment at MD Anderson may include one or more of the following therapies:

Surgery

Surgery is the most common treatment for colon cancer, especially if it has not spread. As for many cancers, surgery for colon cancer is most successful when done by a surgeon with a great deal of experience in the procedure. 

Colon cancer may be treated with surgery alone, surgery and chemotherapy, and/or other treatments. Chemotherapy or radiation may be given:

• Before surgery to make the cancer smaller. This is called neoadjuvant therapy.
• After surgery to help keep you cancer-free. This is called adjuvant therapy.

The type of surgery depends on the stage and location of the tumor:

Polypectomy: A colonoscope, which is a long tube with a camera on the end, is inserted into the rectum and guided to the polyp. A tiny, scissor-like tool or wire loop removes the polyp.

Colectomy: The area of the colon where the cancer is, along with some healthy surrounding tissue, is removed. The associated lymph nodes are removed (biopsied) and looked at under a microscope. Usually the surgeon then rejoins the parts of the colon. This surgery also is called a hemicolectomy or partial colectomy.

Your doctor will decide whether it is best to perform traditional open surgery or minimally invasive laparoscopic surgery.

With minimally invasive surgery, small cuts are made in the abdomen. A tiny camera and surgical instruments are inserted. The surgeon then uses video imaging to perform the surgery. MD Anderson surgeons are among the most experienced in the nation in minimally invasive colon cancer surgery.

Endoscopic mucosal resection (EMR) may be used if the cancer is small and only on the surface of the colon. A needle is placed in the colon wall, and then saline (saltwater) is injected to make a bubble under the growth. Using suction, the lesion is removed.

Endoluminal stent placement: This minimally invasive procedure uses an endoscope to place expanding metal stents to help relieve a bowel obstruction.

Chemotherapy

MD Anderson offers the most up-to-date and effective chemotherapy options for colon cancer. Drugs are given by mouth (pills) or intravenously (injected into a vein).

• Chemotherapy may be used to help:
• Shrink the cancer before surgery
• Keep you cancer free after surgery
• Prolong life when surgery is not an option

Targeted Therapies

MD Anderson offers targeted therapies for certain types of colon cancer. These innovative new drugs stop the growth of cancer cells by interfering with certain proteins and receptors or blood vessels that supply the tumor with what it needs to grow, survive and spread.

Radiation Therapy

MD Anderson provides the most advanced radiation treatments, including:

• Brachytherapy: Tiny radioactive seeds are placed in the body close to the tumor
• 3D-conformal radiation therapy: Several radiation beams are given in the exact shape of the tumor
• Intensity-modulated radiotherapy (IMRT): Treatment is tailored to the specific shape of the tumor to reduce damage to normal tissue.

Proton Therapy

The Proton Therapy Center at MD Anderson treats many colon cancer patients. Proton therapy delivers the highest radiation doses directly into the tumor, sparing nearby healthy tissue and vital organs. For many patients, this results in better cancer control with fewer side effects.