Colon cancer starts in cells of the colon, also called the large intestine. The colon and the rectum form the last part of your digestive system. The colon removes water from digested food and stores waste until it leaves your body as bowel movements.
What are colon cancer symptoms?
The most common signs of colorectal cancer include:
- Bloating or feeling full quickly when eating
- Having cramping or other stomach discomforts that does not go away
- Diarrhea or constipation, especially if they happen often
- Blood in your stool (poop)
- Unintended weight loss
- Back pain and weakness in one or both legs
- Nausea or vomiting
Is colon cancer survivable?
If colon cancer is found early, it can be treated successfully in most cases. People with later-stage colon cancer have a poorer outlook.
Five-year survival rates are about 57 percent for people whose cancers are diagnosed early, while the rate drops to less than 14 percent when the disease has spread to distant parts of the body.
Surgery may offer some benefit for people whose colon cancer is caught at an advanced stage. This includes removing part of the tumor and nearby lymph nodes (lymph node dissection) or complete removal of the colon (colectomy). The results depend on the size and location of the tumor and how much nearby tissue is affected.
People whose colon cancer returns after surgery, chemotherapy, or radiation therapy may be helped by a type of drug called targeted therapy. These drugs attack specific molecules in cancer cells that allow them to grow and spread.
What causes colon cancer?
The exact cause of most cases of colorectal cancer isn’t known, but certain factors can increase your risk for developing it:
Age – The chance of getting colorectal cancer increases as you get older. Colorectal cancer also occurs more often in people with family members with colon or rectal cancers at an early age (younger than 45).
Race: The rate of colon cancer in African Americans is 50 percent higher than the rate in whites. Colorectal cancer occurs more often among Hispanic/Latinos, Asian Americans, and American Indians/Alaska Natives. 
Family history: Your risk for colorectal cancer may be increased if other close relatives have had it at a younger age or several family members developed it at an older age.
Diet: A diet high in processed meats (meat that has been preserved by smoking, curing, or salting) and low in fruits and vegetables is linked with a higher risk of colorectal cancer.
When should I see a doctor about colon cancer?
If you have any signs or symptoms that worry you, make an appointment with your doctor so they can determine what’s causing them and whether they might be related to colon cancer. In addition, if you’re age 45 or older and have not been getting regular colon cancer screenings as recommended, talk with your doctor about scheduling one.