Cancer is a group of many related diseases. All cancers begin in
cells, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body. Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or
tumor.
Tumors can be benign or malignant.
Benign tumors are not cancer. Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer. They are generally more serious. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original (
primary) tumor to form new tumors in other organs. The spread of cancer is called
metastasis.
Colorectal Cancer
Colorectal cancer is the second most common cancer overall in the United States. Only lung cancer is more common.
Fortunately, the number of people diagnosed with colorectal cancer has been decreasing over the last 20 years, partly as a result of more screening, which results in finding and removing colorectal polyps before they turn into cancer. The number of Americans who die from colorectal cancer has also declined in the last 20 years. This reflects the declining number of people diagnosed with colorectal cancer as well as improvements in early detection and treatment.
The Colon and Rectum
Cancer that begins in the colon is called Colon Cancer, and cancer that begins in the rectum is called Rectal Cancer. Cancer that starts in the colon or rectum may also be called colorectal cancer.
The colon and rectum are part of the body’s digestive system. The digestive system takes in nutrients (like vitamins and proteins) from foods and helps pass waste material out of the body. The organs in the digestive system include the esophagus, stomach, and the small and large intestines.
The first 6 feet of the large intestine are called the large bowel, or
colon. The last 6-8 inches are the
rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).