Colorectal Cancer

Colorectal Cancer is the second leading cancer killer trailing only lung cancer in annual US deaths.

Overview

The colon and rectum are organs of the digestive system. They are located in the abdomen between the small intestine and the anus. Together, the colon and rectum make up the large intestine or large bowel. Because of their close relationship, cancers of the two organs are often discussed together under the name colorectal cancer.

The colon begins at the cecal valve, its connection to the small intestine, and continues for about 6 feet to its connection with the rectum. Along this length, the colon takes several paths.

The part that travels up vertically on the right side of the abdomen is the ascending colon. The transverse colon extends across the abdomen. The descending colon leads down vertically on the left side of the body. At this point, the sigmoid (S-shaped) colon extends to the rectum.

The 8- to 10-inch long rectum is the last section of the large intestine and leads to the anus.

The colon and rectum have two major jobs or functions. The colon absorbs water and minerals from food and transports them into the bloodstream. The rectum stores fecal matter until it is eliminated from the body.

Colon carcinomas may occur any where in the large intestine- from the cecal valve to the rectum. However, the majority of colon cancers appear to occur in the right (ascending) colon. It is not clear if this is due to more effective screening on the right side or if there is a true increase in right sided cancers.

Incidence
Colorectal cancer generally occurs in 1 out of every 20 individuals at some point in their lifetimes. Approximately 150,000 new cases are diagnosed each year in this country. This is about 15% of the total number of new cancer diagnoses. Colorectal cancer causes about 56,000 deaths a year in the United States, although this number appears to have been declining over the past two decades.

When colorectal cancer is detected early, survival rates are much higher. For example, 92% of patients who receive early treatment are still alive after 5 years. When adjacent organs or lymph nodes are affected, 64% of people survive 5 years. If the cancer is carried to distant organs, the rate drops to only 7%.

Since these statistics are based on patients who were treated 5 years ago, patients currently undergoing treatment may show higher survival rates due to more effective detection and treatment methods.

Most professionals believe that colorectal cancer develops gradually over a period of years. Cells change from a precancerous state to a cancerous state during this time. Thus it is essential that patients undergo screening for early detection of precancerous conditions.

What is colorectal cancer?

Colorectal cancer is a disease in which cells in the colon or rectum become abnormal and divide without control or order, forming a mass called a tumor. (The colon and rectum are parts of the body’s digestive system that remove nutrients from food and water and store solid waste until it passes out of the body.) Cancer cells invade and destroy the tissue around them. They can also break away from the tumor and spread to form new tumors in other parts of the body.

Colorectal cancer is the fourth most common type of cancer and the second leading cause of cancer death in the United States. The number of new cases and deaths resulting from this disease is decreasing. Still, over 135,000 new cases are diagnosed and more than 56,000 people die from colorectal cancer each year.

Who is at risk for colorectal cancer?

The exact causes of colorectal cancer are not known. However, studies show that certain factors increase a person’s chance of developing colorectal cancer:

* Age—Colorectal cancer is more likely to occur as people get older. Although the disease can occur at any age, most people who develop colorectal cancer are over the age of 50.
* Polyps—Polyps are benign (noncancerous) growths that protrude from the inner wall of the colon or rectum. They are relatively common in people over age 50. Because experts believe most colorectal cancers develop in polyps, detecting and removing these growths may be a way to help prevent colorectal cancer. The procedure to remove polyps is called a polypectomy.

Familial adenomatous polyposis, or FAP, is a rare, inherited condition in which hundreds of polyps develop in the colon and rectum. Because this condition is extremely likely to lead to colorectal cancer, it is often treated with surgery to remove the colon and rectum (colectomy). Rectum-sparing surgery may be an option. Researchers are studying the use of anti-inflammatory drugs as a treatment for FAP.
* Personal history—A person who has already had colorectal cancer may develop colorectal cancer a second time. Also, research studies show that women with a history of ovarian, uterine, or breast cancer have a higher-than-average chance of developing colorectal cancer.
* Family history—Close relatives (parents, siblings, or children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the family member developed the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
* Ulcerative colitis or Crohn’s colitis—Ulcerative colitis is a condition that causes inflammation and sores (ulcers) in the lining of the colon. Crohn’s colitis (also called Crohn’s disease) causes chronic inflammation of the gastrointestinal tract, most often the small intestine (the part of the digestive tract that is located between the stomach and the large intestine). People who have ulcerative colitis or Crohn’s colitis may be more likely to develop colorectal cancer than people who do not have these conditions.
* Diet—Some evidence suggests that the development of colorectal cancer may be associated with a diet that is high in fat and calories and low in foods with fiber, such as whole grains, fruits, and vegetables. Researchers are exploring what role these and other dietary components play in the development of colorectal cancer

To see links to many cancer and colorectal cancer web sites, click here.