The term “colorectal cancer” encompasses any cancer that starts in the colon or the rectum. Though they are two separate cancers, colon and rectal cancer are very similar, and therefore they are often discussed together under the term “colorectal cancer.” Excluding skin cancers, colorectal cancer is the third most common cancer found in both men and women in the U.S. About one in 20 people will develop colorectal cancer in his or her lifetime.
In most cases, colorectal cancer begins as a polyp, or growth, in the inner lining of the colon or rectum. There are many types of polyps, many of which are not cancerous. Adenomas are the only type of polyp that may become cancerous, and early detection and removal of a polyp can prevent it from becoming cancer.
The American Cancer Society estimates there will be about 93,090 new cases of colon cancer and about 39,610 cases of rectal cancer this year. An estimated 49,700 people will die from colorectal cancer this year.
In 2000, President Clinton declared March to be National Colorectal Cancer Awareness Month to open up a national discussion about colorectal cancer.
Signs and symptoms of colorectal cancer
Most people in the early stages of colorectal cancer do not have symptoms until the cancer grows and develops. Possible symptoms for colorectal cancer include:
- Change in bowel habits
- Constant feeling of needing to have a bowel movement, even after doing so
- Blood in the stool, dark stools, rectal bleeding
- Cramping or stomach pain
- Weakness or tiredness
- Unexplained weight loss
- Low red blood cell count
It’s important to remember that most of these symptoms have other causes unrelated to colorectal cancer. However, if you do experience any of these symptoms, you should see your doctor.
Risk factors of colorectal cancer
Researchers have identified several risk factors for colorectal cancer. Some of these factors we have no control over, while others are within our ability to change. The risk factors for colorectal cancer include:
- Age (risk increases with age)
- Previous polyps or colorectal cancer
- History of ulcerative colitis or Crohn’s disease
- Family history of colorectal cancer
- Race (people of African-American or Ashkenazi descent are at higher risk)
- Type 2 diabetes
- Hereditary syndromes, such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (Lynch syndrome)
- Diet that is high in red meats or processed meats
- Eating meats cooked at high heat (fried, broiled, grilled)
- Lack of exercise
- Being overweight or obese
- Heavy alcohol use
Preventing colorectal cancer
The exact cause of most colorectal cancers is unknown, but many of them can be prevented. Changing high-risk lifestyle factors—such as diet and activity level—and getting regular screenings are the best ways to prevent colorectal cancer. During a screening, doctors will look for signs of cancer or pre-cancer. Screening can also help find polyps, which can be removed before they turn into cancer.
Screening tests for colorectal cancer include:
- Checking stool samples for blood, which might be a sign of a polyp or cancer (fecal occult blood test or fecal immunochemical test).
- Inserting a flexible, lighted tube into the rectum and lower colon to check for polyps and cancer (sigmoidoscopy).
- Inserting a longer, flexible tube to examine the entire rectum and colon (colonoscopy).
- X-ray test of the colon and rectum (double contrast barium enema).
- CT scan of the colon and rectum.
Treatment of colorectal cancer
Depending on the stage of your cancer, your doctor may recommend one or a combination of the following:
- Radiation therapy
- Targeted therapies
Regular screening for colorectal cancer should begin at age 50. However, if you have a family history of colorectal cancer, inflammatory bowel disease, Crohn’s disease, ulcerative colitis or a genetic syndrome related to colorectal cancer, your doctor may recommend early screening.