Colorectal cancer is the abnormal proliferation of cells in the colon or rectum. It is considered to be the most common gastro-intestinal cancer, third most common cancer, and the second leading cause of death from cancer in the United States. It is estimated that in 2007, there were about 154, 000 new cases with a mortality rate of 10% to 15%. At some point in one’s lifetime, 1 out of 17 people can develop this type of cancer.
Etiology
The cause of cancer of the colon and rectum is not well-defined. It occurs equally in both men and women and in all races. However, the highest colorectal cancer incidence occurs among African-Americans. It may be related to consumption of low-fiber, high fat diet as well as highly-refined foods with insufficient intake of fruits and vegetables. There is a higher incidence in cities of industrialized countries and among obese clients with sedentary lifestyles.
Risk Factors
Diet
Epidemiologic studies reveal that of all the colorectal cancer risk factors, diet is the most important easily modifiable. Individuals consuming a low-fiber, high-fat diet have a greater chance of developing this disease. This type of diet oftentimes leads to constipation, which allows stool to remain in your bowel for longer periods of time. Researchers proposed that these metabolic and bacterial end products are carcinogenic and raises the probability of acquiring cancer.
Age
Colorectal cancer incidence increases sharply with age, with 90% developing after 50 years old and increases with each decade, thereafter. Nevertheless, this form of cancer has also been known to develop in younger people.
Other Risk Factors
History of breast, ovarian and endometrial cancer somehow increases the likelihood of developing cancer of the color or rectum. Genetic predisposition to familial adenomatous polyposis, a disorder characterized by the early onset of hundreds to thousands of non-cancerous growths on the inner wall throughout the large intestine, and inflammatory bowel diseases such as your ulcerative colitis are colorectal cancer risk factors as well.
Diagnostic Tests
Early colorectal cancer screening and detection can decrease its incidence and mortality by leading to early removal of precancerous lesions. When the disease is suspected, barium enema or colonoscopy will be ordered by your doctor. Barium enema involves taking x-rays of your colon and rectum after an enema, a liquid substance containing barium, is introduced into your rectum and colon via the anus. Colonoscopy, on the other hand, is a procedure wherein your doctor inserts a long, flexible viewing tube into the rectum so he can inspect the inside of the entire colon. Screenings such as your Digital Rectal Examination and stool occult blood test are also available for early detection of colorectal cancer.
Pathophysiology
More than 95% of this cancer begins with a polyp, an abnormal growth of tissue projecting from the mucous membrane of your colon. This mostly takes 5 to 10 years or more to become malignant. As a polyp becomes malignant, it increases in size and begins to invade the bowel wall. Tumors in the intestine tend to be bulky and cause death of the tissue and ulceration.
Malignant bowel tumors spread through direct extension to a nearby organ, such as from your colon to your stomach, lymph and blood vessels, or through implanting cells to the peritoneal cavity, the lining of your abdominal wall.
Signs and symptoms
- Rectal bleeding
- Changed bowel habits
- Abdominal pain
- Weight loss
- Anemia
- Anorexia
- Ribbon-like stools
Generally, tumors found in the small bowel and right colon, usually cause abdominal pain, cramping nausea and vomiting. Because your large intestine descends, tumors located there have lesser manifestations. At this location, however, lesions often ulcerate resulting in anemia and dark, reddish, brown stools. Obstruction in the descending colon and rectum often leads to ribbon-like stools as new, softer tools often seep out through the obstructed area.
Medical Management
The primary treatment is surgery. However, chemotherapy is used as an adjunct to decrease survival in tumors that cannot be removed. Radiation therapy is also used before surgery in order to decrease the size of the tumor and make it easier to remove.
Prevention
- Have regular check-ups with your doctor and perform colorectal cancer screenings and tests as early as possible, especially if you are high-risk. Colorectal cancer incidence is greatly reduced among men and women who have regular screenings.
- Get rid of all modifiable colorectal cancer risk factors such as smoking, physical inactivity, obesity and a diet low in fiber and high in fats. Also, eat a variety of fruits, vegetables and whole grains. These contain antioxidants that play a role in cancer prevention.