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Colorectal cancer starts in the colon or the rectum (the largest part of the intestine located near the anus). Because they share common features, they are often referred to together as colorectal cancer. Colorectal cancer can lead to death if found too late to be treated. When discovered early, it is usually very treatable and not life threatening.
Symptoms of colorectal cancer
The primary symptom of colorectal cancer is a polyp (a growth). It cannot be seen without the use of a camera during a colonoscopy (invasive procedure to check the health of your colon and rectum). As the polyp grows, it increases the chances it will become cancerous. Once a polyp develops, it may lead to the following symptoms:
- Bleeding from your rectum.
- Blood in your stool or in the toilet after you have a bowel movement.
- Changes in the shape or consistency of your stool (diarrhea or constipation lasting several weeks).
- Stomach cramps.
- Stomach discomfort, such has the urge to have a bowel movement when you don’t really need to have one.
- Weakness or fatigue.
- Unplanned weight loss.
Other medical conditions can cause these same symptoms. See your doctor to find what is causing your symptoms.
What causes colorectal cancer?
There are several genetic and environmental causes of colorectal cancer. These include:
- Age (over 60).
- Ethnicity, including African-American and Eastern European.
- Prior history of polyps.
- Family history of colorectal cancer.
- Inflammation of the colon (ulcerative colitis and Crohn’s disease).
- Inherited genetic syndromes (Lynch syndrome, Peutz-Jeghers syndrome).
- Poor diet. Specifically, a low-fiber, high-fat diet may lead to colorectal cancer.
- Lack of exercise.
- Excess alcohol.
- Radiation cancer therapy.
After the age of 50, doctors recommend you undergo screening every five to 10 years. If you are in one of these groups, you may also need to be tested more often.
The American Association of Family Physicians (AAFP) recommends screening for colorectal cancer with fecal tests, flexible sigmoidoscopy, or colonoscopy (tests used to diagnose colorectal cancer) starting at age 50 and continuing until age 75 years.
For adults between the ages of 76 and 85, the AAFP recommends that the decision to screen for colorectal cancer be an individual one. Your doctor will offer advice based on your overall health and prior screening history.
How is colorectal cancer diagnosed?
Colorectal cancer is diagnosed through several methods. First, if you follow routine screening recommendations, this can find polyps or cancers before they are large enough to cause symptoms. Screening tests are important because early detection means that the cancer can be more effectively treated.
Once you notice symptoms, your doctor will discuss those symptoms and perform a physical exam called a digital rectal exam. In this exam, your doctor will put his or her gloved finger into your rectum to feel for growths. It is not painful. However, it can be uncomfortable. Additional tests might include:
- Barium enema. For this test, you are given an enema (fluid injected into the rectum). The liquid contains a dye that makes your colon show up on an X-ray. Your doctor looks at the X-ray to find abnormal spots in your entire colon. If you have an abnormal spot or if the radiologist detects polyps, your doctor will probably want you to have colonoscopy.
- Fecal occult blood test. This test checks your stool for blood that you can’t see. Your doctor gives you a test kit and instructions to use it at home. Then, you return a stool sample to your doctor for testing. If the lab finds blood, another test is done to look for a polyp, cancer, or another cause of bleeding. Your doctor will ask you to not eat certain foods or take certain medicines a few days before the test. This includes raw vegetables, horseradish, red meat, non-steroidal anti-inflammatory drugs, blood thinners, vitamin C supplements, iron supplements, and aspirin. Some medical conditions, like hemorrhoids, also can interfere with test result.
- Stool DNA Test. This test checks your stool for cells that are shed by colon cancers or precancerous polyps. Your doctor will give you a test kit with instructions on how to collect a stool sample. Your doctor may ask you to not eat certain foods or take certain medicines that may interfere with test results a few days before the test. If your test is positive, your doctor will probably want you to have a colonoscopy.
- Colonoscopy. This test involves inserting a thin, flexible tube into your rectum. The tube is connected to a video camera that can see your entire colon. The tube also can be used to remove polyps and cancers during the exam. Before you have this test, you are given a medicine to make you relaxed and sleepy. A colonoscopy may be uncomfortable. It is usually not painful.
- Virtual colonoscopy. This new test uses a computerized tomography (CT) machine to take pictures of your colon. Your doctor can then see all of the images combined in a computer to check for polyps or cancer. If your doctor finds polyps or other abnormalities in your colon, you will need to have a traditional colonoscopy for further testing or to remove them.
- Flexible sigmoidoscopy. In this test, your doctor puts a thin, flexible, hollow tube with a light on the end into your rectum. The tube is connected to a tiny video camera so the doctor can look at the rectum and the lower part of your colon. This test can be uncomfortable. However, it lets your doctor see polyps when they are very small (before they can be found with a fecal occult blood test). Flexible sigmoidoscopy may miss cancerous polyps that are in the upper part of the colon. Therefore, some doctors prefer a colonoscopy. Your doctor will discuss these options with you.
If you have been diagnosed with colorectal cancer, your cancer will be given a stage. Cancer stages include stage I, stage II, stage III, and stage IV. Stage IV is considered advanced cancer. Stage I cancers offer more hope in a successful outcome after treatment.
Can colorectal cancer be prevented or avoided?
They cannot be prevented or avoided. However, you can reduce your risk by choosing a healthy diet, exercise, losing weight, quitting smoking, and reducing the amount of alcohol your drink. Genetics tests can tell you if you carry an inherited gene that increases your risk of colorectal cancer. Discuss this option with your doctor, including the costs.
Colorectal cancer treatment
If you have cancer of the colon or rectum, your doctor will probably talk to you about various treatment options, including:
- Surgery to remove the tumor is usually the main treatment for colon and rectal cancer.
- Chemotherapy is treatment with drugs that kill cancer cells. Chemotherapy is often used when there is a risk that the colon or rectal cancer will come back. Chemotherapy drugs are used to kill cancer cells that may have been left behind after a tumor is removed by surgery. Chemotherapy is usually combined with another treatment called immunotherapy. During immunotherapy, a person takes drugs that help the immune system fight cancer. Research has shown that the combination of chemotherapy (to kill cancer) and immunotherapy (to help the immune system fight cancer) helps prevent the spread of colon and rectal cancer better than just chemotherapy.
- Radiotherapy (radiation) is treatment with X-rays that kill cancer cells. Radiation may be used either before or after surgery for rectal cancer. Sometimes both radiation and chemotherapy are used after surgery. Radiation may be used to treat colon and rectal cancer. With colorectal cancer, there is a risk that the cancer may come back in the pelvic area. Radiation reduces this risk. If you have stage II or III colorectal cancer, the risk of the cancer coming back is significant. Your doctor would likely recommend the use of radiation in addition to surgery. Chemotherapy and radiation together have been shown to improve the outcome in rectal cancer treatment. Sometimes, radiation is given before surgery for rectal cancer to shrink the tumor and prevent return of the cancer in that area.
Cancer treatment affects people differently. Some people have few side effects or none at all. However, the side effects of cancer treatment make many people feel very sick. Also, talk to your doctor about clinical trials available to people with colorectal cancer. Clinical trials offer new research-based treatments that may or may not be effective. People enrolled in clinical trials must qualify for the trial.
Living with colorectal cancer
Living with colorectal cancer can cause fear and discomfort, depending on the stage of your cancer. If you were treated successfully and are cancer free, you will be required to have regular screenings throughout the rest of your life. This may cause fear and anxiety about the cancer returning.
Questions to ask your doctor
- Is it too late to successfully beat colorectal cancer if I see blood in my stool?
- If I have to have surgery to remove all or part of my colon, will I have to have a colostomy bag?
- What is the recurrence rate for colorectal cancer caught and treated early?
- Are there other reasons for blood in your stool?
Copyright © American Academy of Family Physicians
This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.