Alternate Names : Colorectal Cancer
Colorectal cancer affects the lining of the large intestine and rectum.
What is going on in the body?
The colon is also called the large intestine. The colon begins near the junction of the small intestine and extends to the rectum. The colon has four parts:
the cecum, which lies on the right side of the body
the ascending colon, which rises slightly as it crosses from the right to the left side
the transverse colon, which runs across the abdomen
the descending colon, which drops down from the left side of the body
the sigmoid colon, a U-shaped bend of bowel that leads toward the rectum
Colorectal cancer starts in the lining, or mucosa, of the bowel. It usually develops in one area of the bowel over a long period of time. It occurs on the left side in the descending colon 40% to 50% of the time. The cancer grows along the opening in the colon. It also can grow further into the lining and muscle tissue.
Like other tumors, colorectal cancer can spread to lymph nodes and other parts of the body.
What are the causes and risks of the disease?
Colorectal cancer is the third most common cancer. People have an increasing risk for it starting at the age of 40. People over the age of 50 account for 93% of colorectal cancer cases.
Experts believe that this slow-growing cancer begins when normal cells in the mucosa become overactive. These overactive cells form a small benign tumor called an adenoma. Abnormal cell changes continue, ultimately turning into cancer. Several genes play a role in colorectal cancer, too.
Some risk factors for the disease are:
small growths in the colon called colorectal polyps
polyp syndromes, which means that colorectal polyps form frequently
a family history of colorectal cancer
ulcerative colitis, a chronic inflammatory disease of the bowel mucus, or inflammation of the colon that results in ulcers
Certain foods increase the risk for getting this disease, such as:
eating a lot of meat
eating a diet high in fat and low in fiber