Source: Cancer.gov (Colon cancer) (Rectal Cancer)
Colon cancer is a disease in which malignant (cancer) cells form in the tissues of the colon.
The colon is part of the body’s digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of 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 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).
Gastrointestinal stromal tumors can occur in the colon. See the PDQ summary on Gastrointestinal Stromal Tumors Treatment for more information.
See the PDQ summary about Unusual Cancers of Childhood for information about colorectal cancer in children.
Health history can affect the risk of developing colon cancer.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors include the following:
- A family history of cancer of the colon or rectum.
- Certain hereditary conditions, such as familial adenomatous polyposis and hereditary nonpolyposis colon cancer (HNPCC; Lynch Syndrome).
- A history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn disease.
- A personal history of cancer of the colon, rectum, ovary, endometrium, or breast.
- A personal history of polyps
(small areas of bulging tissue)
in the colon or rectum.
Polyps in the colon. Some polyps have a stalk and others do not. Inset shows a photo of a polyp with a stalk.
Signs of colon cancer include blood in the stool or a change in bowel habits.
These and other signs and symptoms may be caused by colon cancer or by other conditions. Check with your doctor if you have any of the following:
- A change in bowel habits.
- Blood (either bright red or very dark) in the stool.
- Diarrhea, constipation, or feeling that the bowel does not empty all the way.
- Stools that are narrower than usual.
- Frequent gas pains, bloating, fullness, or cramps.
- Weight loss for no known reason.
- Feeling very tired.
- Vomiting.
Rectal cancer is a disease in which malignant (cancer) cells form in the tissues of the rectum.
The rectum is part of the body’s digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of 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 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).
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. The following are possible risk factors for rectal cancer:
- Being aged 40 or older.
- Having certain hereditary conditions, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC or Lynch syndrome).
- Having a personal history of any of the following:
- Colorectal cancer.
- Polyps (small pieces of bulging tissue) in the colon or rectum.
- Cancer of the ovary, endometrium, or breast.
- Having a parent, brother, sister, or child with a history of colorectal cancer or polyps.
Signs of rectal cancer include a change in bowel habits or blood in the stool.
These and other signs and symptoms may be caused by rectal cancer or by other conditions. Check with your doctor if you have any of the following:
- A change in bowel habits.
- Diarrhea.
- Constipation.
- Feeling that the bowel does not empty completely.
- Stools that are narrower or have a different shape than usual.
- Blood (either bright red or very dark) in the stool.
- General abdominal discomfort (frequent gas pains, bloating, fullness, or cramps).
- Change in appetite.
- Weight loss for no known reason.
- Feeling very tired.
