Are you at a risk for colorectal cancer disease?
What Is Colorectal Cancer?
Colorectal cancer (CRC) is the third most common cancer worldwide after lung and breast cancers with two-thirds of all CRCs occurring in the more developed regions of the world. CRC affects men and women of all racial and ethnic groups, and is most often found in those aged 50 years or older.
Colorectal cancer is a cancer that starts in the colon or the rectum. These cancers can also be named colon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer are often grouped together because they have many features in common.
Cancer starts when cells in the body start to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body.
How does colorectal cancer start?
Most colorectal cancers start as a growth on the inner lining of the colon or rectum. These growths are called polyps. Some types of polyps can change into cancer over time (usually many years), but not all polyps become cancer. The chance of a polyp changing into cancer depends on the type of polyp.
Where does colorectal cancer grow?
To understand colorectal cancer, it helps to understand the parts that make up the colon and rectum. The colon and rectum make up the large intestine (or large bowel), which is part of the digestive system, also called the gastrointestinal (GI) system.
Most of the large intestine is made up of the colon, a muscular tube about 5 feet long. The parts of the colon are named by which way the food is traveling through them.
- The first section is called the ascending colon. It starts with a pouch called the cecum, where undigested food is comes in from the small intestine. It extends upward on the right side of the abdomen (belly).
- The second section is called the transverse colon. It goes across the body from the right to the left side.
- The third section is called the descending colon because it descends (travels down) on the left side.
- The fourth section is called the sigmoid colon because of its “S” shape. The sigmoid colon joins the rectum, which connects to the anus.
The ascending and transverse sections together are called the proximal colon. The descending and sigmoid colon are called the distal colon.
Factors that may increase your risk of colon cancer include:
- Older age: Colon cancer can be diagnosed at any age, but a majority of people with colon cancer are older than 50. The rates of colon cancer in people younger than 50 have been increasing, but doctors aren’t sure why.
- A personal history of colorectal cancer: If you’ve already had colon cancer or noncancerous colon polyps, you have a greater risk of colon cancer in the future.
- Inflammatory intestinal conditions: Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn’s disease, can increase your risk of colon cancer.
- Inherited syndromes that increase colon cancer risk: Some gene mutations passed through generations of your family can increase your risk of colon cancer significantly.
- Family history of colon cancer: You’re more likely to develop colon cancer if you have a blood relative who has had the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater.
- Low-fiber, high-fat diet: Colon cancer and rectal cancer may be associated with a typical Western diet, which is low in fiber and high in fat and calories. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meat.
- A sedentary lifestyle: People who are inactive are more likely to develop colon cancer. Getting regular physical activity may reduce your risk of colon cancer.
- Diabetes: People with diabetes or insulin resistance have an increased risk of colon cancer.
- Obesity: People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight.
- Smoking: People who smoke may have an increased risk of colon cancer.
- Alcohol: Heavy use of alcohol increases your risk of colon cancer.
Signs and symptoms of colon cancer include:
- A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool
- Rectal bleeding or blood in your stool
- Persistent abdominal discomfort, such as cramps, gas or pain
- A feeling that your bowel doesn’t empty completely
- Weakness or fatigue
- Unexplained weight loss
Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in your large intestine.
The recommendations on this page are based on literature from the American Society of Clinical Oncology and American Society of Colon and Rectal Surgeons.