The colon (also called the large intestine) is a long tube with muscular walls in the digestive system that connects the small intestine to the anus. After food digests in the small intestine, the remaining material travels through the colon.
Colon cancer occurs when cancerous cells form in the tissues of the colon. Most colon cancers are adenocarcinomas, which begin in cells that make and release mucus and other fluids.
The rectum is the last several inches of the large intestine closest to the anus. Rectal cancer occurs when cancer cells develop in the tissues of the rectum. Because these types of cancer begin in the same tissue, they are often grouped into one type called colorectal cancer.
The source for this information is the National Cancer Institute.
Several factors influence the risk of developing colorectal cancer:
- Age: Colorectal cancers are more likely to occur as people get older. More than 90% of people with this disease are diagnosed after age 50.
- Colorectal polyps: Polyps (also called adenomas) are growths on the inner wall of the colon or rectum. They are common in people over age 50. Most polyps are benign (not cancer), but some can become cancer. Finding and removing polyps may reduce the risk of colorectal cancer.
- Family history of colorectal cancer: Close relatives (parents, siblings, or children) of a person with a history of colorectal cancer may be more likely to develop this disease themselves, especially if the relative had the cancer at a young age. If many close relatives have a history of colorectal cancer, the risk is even greater. Learn more about hereditary cancer risk from our Family Cancer Assessment Clinic.
- Genetic changes: Changes in certain genes increase the risk of colorectal cancer.
- Hereditary nonpolyposis colon cancer (HNPCC) is the most common type of inherited (genetic) colorectal cancer. It accounts for about 2% of all colorectal cancer cases. It is caused by changes in an HNPCC gene. Most people with an altered HNPCC gene develop colon cancer, and the average age at diagnosis of colon cancer is 44.
- Familial adenomatous polyposis (FAP) is a rare, inherited condition in which hundreds of polyps form in the colon and rectum. It is caused by a change in a specific gene called APC. Unless FAP is treated, it usually leads to colorectal cancer by age 40. FAP accounts for less than 1% of all colorectal cancer cases.
Family members of people who have HNPCC or FAP can have genetic testing to check for specific genetic changes. For those who have changes in their genes, health care providers may suggest ways to try to reduce the risk of colorectal cancer, or to improve the detection of this disease. For adults with FAP, the doctor may recommend an operation to remove all or part of the colon and rectum. Learn about hereditary risk for cancer from our Family Cancer Assessment Clinic.
- Personal history of cancer: A person who has already had colorectal cancer may develop colorectal cancer a second time. Also, women with a history of ovarian and endometrial cancer are at a somewhat higher risk of developing colorectal cancer.
- Ulcerative colitis or Crohn's disease: A person who has had a condition that causes inflammation of the colon (such as ulcerative colitis or Crohn's disease) for many years has an increased risk of developing colorectal cancer.
- Diet: Studies suggest that diets high in fat (especially animal fat) and low in calcium, folate, and fiber may increase the risk of colorectal cancer. Also, some studies suggest that people who eat a diet very low in fruits and vegetables may have a higher risk of colorectal cancer. More research is needed to better understand how diet affects the risk of colorectal cancer.
- Cigarette smoking: A person who smokes cigarettes may be at increased risk of developing polyps and colorectal cancer.
Because people who have colorectal cancer may develop colorectal cancer a second time, it is important to have regular checkups and screenings. People who have colorectal cancer may be concerned that his or her family members may develop the disease.
People who think they may be at risk should talk to their health care providers. They may be able to suggest ways to reduce the risk and can plan an appropriate schedule for screenings.
A common symptom of colorectal cancer is a change in bowel habits. These include the following:
- Blood (either bright red or very dark) in the stool
- Diarrhea or constipation
- Frequent fatigue
- Frequent gas pains or cramps, or feeling full or bloated
- Nausea or vomiting
- Sensation that the bowel does not empty completely
- Stools are narrower than usual
- Weight loss with no known reason
Other health problems can cause these symptoms. A person with any of these symptoms should see a health care provider so the problem can be diagnosed and treated as early as possible.
Screening tests help doctors find polyps or cancer before symptoms develop. Finding and removing polyps may prevent colorectal cancer. Also, treatment for colorectal cancer is more likely to be effective when the disease is found early.
To find polyps or early colorectal cancer:
- People in their 50's and older should be screened.
- People with a higher-than-average risk of colorectal cancer should talk with their health care providers about whether to have screening tests before age 50, what tests to have, and how often to schedule screenings.
The following screening tests can be used to detect polyps, cancer, or other abnormal areas.
- Fecal occult blood test (FOBT): Sometimes cancers or polyps bleed, and the FOBT can detect tiny amounts of blood in the stool.
- Sigmoidoscopy: The doctor checks inside the rectum and the lower part of the colon with a lighted tube called a sigmoidoscope. If polyps are found, they can be removed.
- Colonoscopy: The doctor examines inside the rectum and entire colon using a long, lighted tube called a colonoscope. The doctor removes polyps that may be found.
- Double-contrast barium enema: The patient is given an enema with a barium solution, and air is pumped into the rectum. Several x-ray pictures are taken of the colon and rectum. The barium and air help the colon and rectum show up on the pictures. Polyps or tumors may show up.
- Digital rectal exam: This exam is often part of a routine physical check-up. The doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas.
If tests show an abnormal area (such as a polyp), a biopsy may be necessary to check for cancer cells. Often, doctors remove tissue (called a biopsy) during a colonoscopy or sigmoidoscopy. A biopsy is the only way to know for sure if cancer is present.
If the biopsy shows that cancer is present, the doctor needs to know the stage (extent) of the disease to plan the best treatment. The stage is based on whether the tumor has invaded nearby tissues, whether the cancer has spread and, if so, to what parts of the body.
Doctors may order some of the following tests:
- Blood tests: Doctors check for specific substances in the blood that indicate cancer is present. Some people who have colorectal cancer have a high level of carcinoembryonic antigen (CEA).
- Colonoscopy: If colonoscopy was not performed for diagnosis, doctors check for abnormal areas along the entire length of the colon and rectum with a colonoscope. Watch our Introduction to Colonoscopy video.
- Endorectal ultrasound: An ultrasound probe is inserted into the rectum. The probe uses high-energy sound waves bounced off internal tissues or organs in the abdomen to make echoes. The echoes form a picture called a sonogram. The picture can be printed to be looked at later.
- X-ray: An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
- CT scan: Doctors often use CT scans to take pictures of tissue inside the body. An x-ray machine linked to a computer takes several pictures. The pictures may show whether cancer has spread to lymph nodes or other areas in the body.
Stages of Colorectal Cancer
Stage 0: Cancer is found only in the innermost lining of the colon or rectum. Stage 0 is also referred to as carcinoma in situ.
Stage I: The tumor has grown into the inner wall of the colon or rectum. The tumor has not grown through the wall.
Stage II: The tumor extends more deeply into or through the wall of the colon or rectum. It may have invaded nearby tissue, but cancer cells have not spread 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, such as the liver or lungs.
Recurrent colon cancer: Cancer that has come back after it has been treated. The cancer may return in the colon or rectum or in another part of the body.
At Huntsman Cancer Institute, colorectal cancer is treated by a team of specialists, including gastroenterologists (doctors who specialize in diseases of the digestive system), surgeons, medical oncologists, radiation oncologists, nurses, social workers, dietitians, and other professionals.
These are common treatments for colorectal cancer:
- Radiation therapy
- Biological therapy
- Clinical trials
A patient may receive more than one type of treatment. The treatment that's right for each patient depends on the stage of the cancer and the patient's overall health before diagnosis.
This is the most common treatment for colorectal cancer. Types of surgery include:
- Colonoscopy: A small malignant polyp may be removed from the colon or upper rectum with a colonoscope. Some small tumors in the lower rectum can be removed through the anus without a colonoscope.
- Laparoscopy: Early colon cancer may be removed with the aid of a thin, lighted tube called a laparoscope. Three or four small cuts are made into the abdomen so a surgeon can see inside. The tumor and part of the healthy colon are removed. Nearby lymph nodes also may be removed. The surgeon checks the rest of the intestine and the liver to see if the cancer has spread.
- Open surgery: The surgeon makes a large cut into the abdomen to remove the tumor and part of the healthy colon or rectum. Some nearby lymph nodes are also removed. The surgeon checks the rest of the intestine and the liver to see if the cancer has spread.
When a section of the colon or rectum is removed, the surgeon can usually reconnect the healthy parts. However, sometimes reconnection is not possible. In this case, the surgeon creates a new path for waste to leave the body. The surgeon makes an opening (stoma) in the wall of the abdomen, connects the upper end of the intestine to the stoma, and closes the other end. The operation to create the stoma is called a colostomy. A flat bag fits over the stoma to collect waste, and a special adhesive holds it in place.
For most people, the stoma is temporary. It is needed only until the colon or rectum heals from surgery. After healing takes place, the surgeon reconnects the parts of the intestine and closes the stoma. Some people, especially those with a tumor in the lower rectum, need a permanent stoma.
This treatment uses high-energy rays to kill cancer cells. It affects cancer cells only in the treated area. Radiation therapy can be given externally (from a machine outside the body), internally (called implant radiation or brachytherapy), or during surgery (called intraoperative radiation therapy).
This treatment uses drugs to destroy or control cancer throughout the body. Learn more about this treatment in our introduction to chemotherapy video.
This treatment helps the body fight cancer, manage side effects, and help prevent cancer. Examples of this include monoclonal antibodies, growth factors, and vaccines.
These studies discover and evaluate new and improved cancer treatments. Patients are encouraged to talk with their doctors about participating in a clinical trial or any questions regarding research studies. For more information, also visit HCI's clinical trials website.
When you or someone you love is diagnosed with cancer, concerns about treatments and managing side effects, hospital stays, and medical bills are common. You may also worry about caring for your family, employment, or how to continue normal daily activities.
Here's where you can go for support:
- Your health care team can answer your questions and talk to you about your concerns. They can help you with any side effects and keep you informed of all your treatments, test results, and future doctor visits.
- Our Patient and Family Support Services professionals offer HCI patients and their families emotional support and resources for coping with cancer and its impact on daily life.
- The Linda B. and Robert B. Wiggins Wellness-Survivorship Center offers support groups, classes, and activities aimed to increase the quality of life and well-being of HCI patients and their families.
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Did You Know?
- The Genetic Information Non-discrimination Act (GINA) prevents health insurance companies from denying coverage or adjusting premiums based on genetic information, and also prevents employers from using genetic information to influence hiring, firing, promotion, or salary-related decisions.
- The Utah Cancer Control Program offers assistance for colorectal cancer screenings to Utah adults who qualify. Call 1-800-717-1811 for more information.
- The colon is usually four to five feet long. The rectum is the last several inches of the colon.