Colon cancer is the growth of cancer in the large intestine. The large intestine, or colon, absorbs water and nutrients from foods. After, the colon passes the solid waste to the rectum for storage, before it is eliminated from the body.
Cancer occurs when cells in the body divide without control or order. Eventually these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths. These growths can invade nearby tissues and spread to other parts of the body. It is not clear exactly what causes these problems in the cells, but it is probably a combination of genetics and environment.
Being over 50 years old increases your chance of colon cancer. Other factors that may increase your chance of colon cancer include:
- Hereditary conditions, such as familial adenomatous polyposis
- Personal history of colon or rectal cancer, or polyps
- Family history of colon or rectal cancer, especially a parent, sibling, or child
- History of ulcerative colitis or Crohn’s disease
- Diets high in meat, and low in fruits, vegetables, and whole grains
- Heavy alcohol intake
- Physical inactivity
In most cases, there are no symptoms with colon cancer. When symptoms do appear, they may include:
- A change in bowel habits
- Blood in the stool that is either bright red or black and tarry
- Stools that are narrower than usual
- Diarrhea, constipation, or feeling that the bowel does not empty completely
- General abdominal discomfort, such as frequent gas pains, bloating, fullness, and/or cramps
- Unexplained weight loss
- Constant feeling of fatigue or tiredness
You will be asked about your symptoms and medical history. A physical exam will be done. The doctor will check the rectum for lumps or abnormal areas, and recommend different tests in order to identify tumors and confirm diagnosis.
Tests used to identify potential colon cancers include:
Additional tests may confirm the presence of colon cancer, determine what stage the cancer is in, and/or determine if the cancer has spread:
- CT scan
- PET scan
- Transrectal ultrasound
- Blood tests to look for anemia and cancer markers in the blood
The physical exam, combined with all of your test results, will help to determine the type and stage of cancer you have. Staging is used to guide your treatment plan. Like other cancers, colon cancer is staged from I-IV. Stage I is a very localized cancer, while stage IV indicates a spread to other parts of the body
Treatment for colon cancer depends on how early it is detected, and the stage or location of the tumor.
Talk with your doctor about the best treatment plan for you. Treatment may include one or more of the following options:
Surgery is the main treatment for colon cancer. There are several options for surgery depending on the location of the cancer and how much it has spread:
- Polypectomy and local excision—Early stage removal of the cancer.
- Partial colectomy—Removal of the cancer with a margin of surrounding healthy tissue and lymph nodes. The healthy ends of the colon are reconnected.
- Laparoscopic-assisted colectomy —Removal of the cancer with a margin of surrounding healthy tissue and lymph nodes through small incisions in the abdomen.
- Total colectomy—Removal of the entire colon. The last part of the small intestine, called the ileum, is then connected to the rectum.
Some surgeries may require temporary or permanent colostomies. A colostomy is a surgical opening through the wall of the abdomen into the colon. This is used as a path for waste material to leave the body. After a colostomy, you will wear a special bag to collect bodily waste.
Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. It is directed at the site of the tumor from a source outside the body. This therapy is aimed at the immediate area of the cancer.
Chemotherapy uses drugs to kill cancer cells. It may be given in many forms, including pill, injection, and catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells. They can also kill some healthy cells. This therapy is systemic, meaning it affects your entire body.
Targeted therapy uses medications to target and kill cancer cells, while sparing healthy tissue. They are currently used to treat advanced cancers. Targeted therapy is less harmful to healthy tissue, which reduces side effects. It may be used alone or in combination with chemotherapy.
Some medications can be used as part of a treatment plan. Other medications may help to either prevent or reduce side effects of treatments, or to manage certain side effects once they occur. These include:
- Blood stem cell support medications
- Antiemetics to control nausea
- Nonsteroidal anti-inflammatory medications
- Opioids to control pain
Tell your doctor when you notice a new symptom, and ask if any of these medications are appropriate for you.
The causes of most cancers are not known. However, it is possible to prevent many colon and rectal cancers by finding and removing polyps that could become cancerous. Beginning at age 50, both men and women with average risk should follow one of the following screening options:
- Colonoscopy every 10 years
- Flexible sigmoidoscopy every 5 years
- CT colonography every 5 years
- Double-contrast barium enema every 5 years
- MR colonography every 5 years
- Stool DNA test every 3 years
- Annual fecal occult blood test (FOBT)
- Annual fecal immunochemical test (FIT)
People with any of the following risk factors should begin colon and rectal cancer screening earlier and/or undergo screening more often:
- African American or Native Americans
- Strong family history of colon or rectal cancer, or polyps
- Family history of hereditary colon or rectal cancer syndromes
- History of colon or rectal cancer, or adenomatous polyps
- History of chronic inflammatory bowel disease
Be sure to discuss colon cancer screening with your doctor to see how and when you should be screened.
There are lifestyle changes that may reduce your risk of colon cancer, such as:
- Not smoking
- Eating a healthful diet high in fruits, vegetables, and whole grains, and low in red meat
- Being physically active by exercising at least 30 minutes a day on most days of the week
- Drinking alcohol in moderation—maximum of 2 drinks per day for men and 1 drink per day for women
- Maintaining a healthy weight
- Reviewer: Mohei Abouzied, MD
- Review Date: 09/2015 -
- Update Date: 09/12/2014 -