Colorectal cancer, also known as colon cancer, develops in the large intestine or the rectum. Cancer occurs when healthy cells become altered, growing and dividing in a way that keeps the body from functioning normally. Most cases of colorectal cancer begin as small, benign clusters of cells (polyps) on the lining of the colon or rectum. Certain types of polyps, called adenomas, can become malignant.
Risk Factors for Colorectal Cancer
Colorectal cancer has several risk factors, some of which are under the patient's control. They include the following:
- Being aged 50 or older
- Lack of exercise
- Excessive alcohol consumption
- Eating red or processed meats
- Certain hereditary syndromes
- Family history of colorectal cancer
- Patient history of adenomas
- Patient history of other cancer
- Type 2 diabetes
Having a history of inflammatory bowel disease also increases the risk of colorectal cancer.
Symptoms of Colorectal Cancer
Although patients with colorectal cancer are often asymptomatic, as it progresses they may experience one or more of the following symptoms:
- Change in bowel habits or change in consistency of the stool
- Rectal bleeding or blood in the stool
- Persistent abdominal discomfort, such as cramps, gas or pain
- Weakness or fatigue
- Unexplained weight loss
- Nausea or vomiting
A feeling that the bowel does not empty completely can also indicate that colorectal cancer is present.
Diagnosis of Colorectal Cancer
After performing a thorough physical examination, and taking a full patient and family history, the doctor may administer other diagnostic tests that include the following:
- Blood tests (including a CBC), and tests for liver enzymes and tumor markers
- Digital rectal examination
- Fecal occult blood test
- Barium enema
- CT scans
As part of a colonoscopy or sigmoidoscopy, a biopsy may be taken.
Treatment of Colorectal Cancer
Depending on the stage of colorectal cancer, treatment includes one or more of the following:
- Surgical removal of diseased and adjacent tissue
- Radiation therapy
Targeted or biological therapy is also an option for treating colorectal cancer.
Prevention of Colorectal Cancer
There are many ways, including eating a healthful low-fat diet that is high in fiber and antioxidants, drinking alcohol only in moderation, exercising regularly, maintaining a healthy weight, and refraining from smoking, to lower the risk of developing colorectal cancer. For people at high risk of developing it, medication and surgery may be recommended. Anyone 50 and older, African-Americans 45 and older, and anyone considered to be at high risk for colorectal cancer should undergo a regularly scheduled colonoscopy.