Colon cancer also known as colorectal cancer, rectal cancer or bowel cancer is malignant disease characterized by cancerous growths (malignant tumor) on the inner wall of the colon, rectum or appendix. It is very dangerous life-threatening disease and one of the leading causes of death among cancers in western countries.
Since colon is the part of digestive system storing waste material, it is very liable of developing tumors that can be malignant or benign. Benign tumors developed on the colon wall are called adenomatous polyps and they can be successful treated by surgery. These tumors are not life-threatening but if untreated they can become malignant over time. In fact colon cancers (malignant colon tumors) most oftenly originate from polyps so it is very important to make regular screening in purpose of early detection.
If left untreated colon cancer may rise and spread to nearby organs such as lungs or liver. This condition is called metastasis and once it starts treatment is unlikely to be successful.
The most common form of colon cancer is called adenocarcinoma. Other types are very rare and they include squamous cell carcinoma and lymphoma.
Although it usually affects older people (above the age of 50) anyone can develop colon cancer. There are many factors that can increase risk such as irregular diet (containing a lot of fat and red meat and little fruit and vegetables, especially in Western world), smoking, physical inactivity and/or obesity, exposure to some viruses such as human papilloma virus, alcohol. Also individuals who had cancers in their past and genetically predispositioned are more likely to be affected. There are many other diseases (usually chronic) that can increase risks such as ulcerative colitis and Crohn's disease of the colon.
Symptoms of colon cancer depend mostly on the site of the lesion. Also very frequently they can be weak or not present at all, especially if lesion if far from the anus. Anyway symptoms may include:
- unusual changes in stools sometimes including smaller diameter of feces
- presence of mucus in stools
- rectal bleeding sometimes including bloody stools
- tarry stools (black feces called melena)
- tenesmus (usually painful feeling of incomplete defecation)
Obstruction of the intestines called bowel abstruction is sometimes possible usually followed by abdominal pain.
Making early detection is very important since colon cancer may take years to develop and chances for curing depend mostly on cancer advanced point. There are many methods for making diagnose. Main include:
- digital rectal exam (DRE) - insertion of doctor's finger in the rectum area
- fecal occult blood test (FOBT) - searching for blood in the stool
- endoscopy - this procedure may include sigmoidoscopy or colonscopy.
Sigmoidoscopy is insertion of lighted probe named sigmoidoscope in the rectum and lower colon. This method can detect polyps and the other abnormalities in this area.
Colonoscopy is similar procedure performed by lighted probe called a colonoscope. It can performe examination of entire colon and if polyps are found during exam they can be immediately removed. This procedure is also used for taking tissue for biopsy.
Picture of colon cancer taken with colonoscope.
Tumor is caused by Crohn's disease.
Treatment of colon cancer depends on many factors and the main is stage of the cancer and patient's overall health. As with many other cancers surgery is main and almost always necessary. There are four main categories of colon cancer surgery: curative, palliative, fecal diversion (known as open-and-close procedure) and bypass.
Chemotherapy is also used usually as addition to surgery.
Although it isn't routine radiation therapy may sometimes be used especially when tumor is located in rectal area.