Colorectal Cancer: Frequently Asked Questions

March 21, 2017

Colorectal Cancer: Frequently Asked Questions

Here are some answers to frequently asked questions about colorectal cancer:

What are the colon and the rectum?

The colon and the rectum are part of the digestive tract.

Illustration of the lower digestive tract.

Together, they form a long tube called the large intestine. This is also called the large bowel. The colon is the first 5 feet or so of this tube. It absorbs water from digested food and stores waste until it passes out of the body. The rectum is a pouchlike structure that makes up the last six inches of the large bowel. It expands to hold waste matter before it passes out of the body through the anus as a bowel movement (stool).

Who gets colorectal cancer?

Colorectal cancer is the third most common cancer in both men and women in the United States. Anyone can develop it, even younger people. There are, though, some people at higher risk. People with a family history of this cancer are at increased risk. So are people who have had it before. People with inflammatory bowel disease (ulcerative colitis or Crohn's disease), type 2 diabetes, or with certain inherited conditions are also at increased risk. Older age is also a factor. About 90% of people with colorectal cancer are older than age 50. The risk is slightly higher in men than in women. African-Americans develop colorectal cancer at a higher rate than other ethnic groups. Jews of Eastern European descent may also be at higher risk. Other people at increased risk include smokers and people who are obese or physically inactive.

What causes colorectal cancer?

Scientists don't know the exact cause. Studies show, though, that genetics, environment, and lifestyle all play a role. For instance, a family history of this cancer increases a person's risk. Some studies show that a diet high in red or processed meat increases the risk. A diet high in fruits and vegetables, on the other hand, may reduce the risk.

Is colorectal cancer inherited?

Most cases of this cancer are "random." That means they are not inherited. But a person who has a parent, sibling, or child who has had this cancer is at higher risk. That risk is even higher if the cancer happened at a young age. Some conditions that can be passed on in families may also increase the risk. An example is inflammatory bowel disease.

Can colorectal cancer be prevented?

A key to prevention is to lower the risk. Diet is one way to do this. The diet should include lots of fruits and vegetables. Little or no exercise seems to increase the risk. Routine exercise may lower it. Being obese (very overweight) also increases risk, so staying at a healthy weight may help prevent it. Studies show that drinking more than moderate amounts of alcohol and smoking increase the risk for this cancer. So avoiding both can lower it. Another important way to lower the risk is to have regular screening tests starting at age 50 and having polyps removed from the intestine.

What is a polyp?

Polyps are benign (noncancerous) growths. They form on the inner wall of the colon or rectum. They are common in people older than age 50. Polyps can cause bleeding or mucus with bowel movements. Large ones can block bowel movements. Some polyps may become cancerous. Polyps are usually found during a screening test. They can be removed by colonoscopy.

Is there some way to find colorectal cancer early?

Screening tests help find the cancer early. It can then be treated before it spreads. These tests also help find polyps before they become cancer. One test is a fecal occult blood test (FOBT). This test checks for blood in the stool. For a sigmoidoscopy, the doctor inserts a lighted tube to see inside the rectum and the lower colon. For a colonoscopy, the doctor inserts a lighted tube inside the rectum and the entire colon. During either test, the doctor can remove polyps or other abnormal tissue or a biopsy. The doctor can then look at the tissue under a microscope for signs of cancer. Other tests that can be used for screening include double-contrast barium enema (an X-ray test),  virtual colonoscopy (a type of CT scan), and a stool DNA test (which looks for gene changes seen in cancer cells).

What is a double-contrast barium enema?

This is a screening test that uses X-rays. First the doctor puts liquid that contains barium into the rectum. Barium is a silver-white compound. It coats the large intestine. That makes the colon and rectum easier to see on X-rays. Then air is pumped into the colon and rectum to expand it. Doctors can then see any growths or tumors. These will need to be removed with a colonoscopy.

What is virtual colonoscopy?

This test, also called CT colonography, is an imaging test used to screen for colorectal cancer. A special type of CT scan is done to create a three-dimensional view of the colon and rectum to allow the doctor to look for polyps. This test is not as invasive as sigmoidoscopy or colonoscopy, but if polyps are seen, a regular colonoscopy will need to be done to remove them.

What is a digital rectal exam?

This exam is also called a DRE. It helps find changes in the lowest four inches of the rectum. To do this test, a doctor or nurse practitioner inserts a lubricated gloved finger into the rectum. The doctor or nurse then feels for lumps. This is not an adequate test by itself to screen for colorectal cancer.

What are the symptoms of colorectal cancer?

Common signs of colorectal cancer include these things:

  • A change in bowel habits that lasts for more than a few days

  • Blood (either bright red or very dark) in the stool

  • Diarrhea, constipation, or a feeling that the bowel is still not empty

  • Gas pains, bloating, fullness, or cramps

  • Stool that is thinner than usual

  • Weakness and fatigue

  • Weight loss for no known reason

Should everyone get a second opinion for a diagnosis of colon cancer?

There are many reasons someone might want to ask for a second opinion. Here are some:

  • A person is not comfortable with the treatment decision.

  • The type of cancer is rare.

  • There is more than one way to treat the cancer.

  • A person is not able to see a cancer expert.

  • A person would like confirmation of the treatment decision.

How can someone get a second opinion?

Here are ways to find someone for a second opinion:

  • Ask a primary care doctor. He or she may be able to suggest a specialist. This may be a surgeon, medical oncologist, or radiation oncologist. Sometimes these doctors work together at cancer centers or hospitals. Never be afraid to ask for a second opinion.

  • Call the National Cancer Institute's Cancer Information Service. The number is 800-4-CANCER (800-422-6237). They have information about treatment facilities. These include cancer centers and other programs supported by the National Cancer Institute.

  • Seek other options. Check with a local medical society, a nearby hospital or medical school, or a support group to get names of doctors who can give you a second opinion. Or ask other people who've had cancer for their recommendations.

How is colorectal cancer treated?

Treatment choices depend on several things, including:

  • The person's age and general health

  • The location of the cancer in the large bowel

  • Whether it has grown through the bowel wall

  • How far it has advanced

  • The results of lab tests on the cancer cells

Surgery is the most common treatment for early stage cancers. The goal is to remove the cancer. Even then, these other treatments may also be used to try to be sure all of the cancer has been treated:

  • Radiation therapy

  • Chemotherapy

More advanced cancers may be treated with:

  • Chemotherapy

  • Targeted therapy

  • Radiation therapy.

What is a colostomy?

A colostomy is a surgical procedure that creates an alternate outlet for stool to leave the body. For it, a surgeon connects a part of the intestine to an opening in the abdominal wall. This opening is called a stoma. This connection gives stool a new way to leave the body. Afterward, the person wears a special bag to collect stool. For most people, this is temporary. After they heal from surgery, the intestines are reconnected and they no longer need the bag. But for some, the stoma and bag are permanent. Most surgeons attempt to maintain a functioning anus whenever possible so that a permanent stoma is not needed.

Is a stoma painful or uncomfortable?

A well-cared-for stoma is painless. It should also not cause discomfort. A person who has one should be able to resume physical activity. A therapist called an enterostomal therapist (ET) can help a person learn how to take care of a stoma. He or she can also help a person adjust to life with a stoma.

Can the body function the way it is supposed to without a large part of the intestines?

Yes. People can live normally without a portion of the small intestine. They can also live normally without the entire large intestine.

What are the sexual side effects from colon or rectal cancer surgery?

Most people return to normal at the end of a recovery period. Sexual side effects are more likely after rectal surgery. For some men, nerves in the rectum may be damaged if the cancer is in the part of the large intestine that is low in the pelvis and near the anus. These nerves are involved with erection. For some women, the vagina may have to be reconstructed. In both cases, it is usually still possible to be intimate.

What are clinical trials?

These are trials to study new cancer treatments. Doctors run them to learn how well new treatments work. They also study the side effects. Treatments that have promise are compared to current treatment. Doctors look to see which works better and which has fewer side effects. People who take part in these studies may benefit. Taking part can give them access to new treatments before they are approved. It also helps future cancer patients by advancing our knowledge of cancer.


March 21, 2017

Reviewed By:  

Alteri, Rick MD,MMI board-certified, academically affiliated clinician