Colon cancer starts in the large intestine, which is the colon. Cancer may also occur in the rectum at the end of the colon, and it is called rectal cancer. The two cancers may be referred to as colorectal cancer. Colon cancers usually begin as noncancerous polyps that develop into cancer. Many people with colon cancer have no symptoms or develop them in the later stages of the disease. Proper screening may be able to detect colon cancer before symptoms develop. This includes fecal occult blood tests and a colonoscopy.
Bowel Habits
A persistent change in bowel habits may be a sign of colon cancer. Symptoms may include diarrhea or constipation. There may be a noticeable difference in the consistency of the bowel movements for about two weeks. There may also be feelings that your bowels are not emptying completely, the Mayo Clinic notes. Symptoms may include partial or complete intestinal blockage. Bowel habits usually change before blockage occurs.
Rectal Bleeding
Bleeding may occur in the rectum or there may be blood in the stool. Colon cancers usually bleed slowly, according to the Merck Manuals. The stool may be streaked or mixed with blood, but the blood is not always noticed. The first sign for many people with colon cancer is bleeding during a bowel movement.
Abdominal Pain
Symptoms might include abdominal discomfort, cramps, unusual bouts of gas or pain. Pain and tenderness may be felt in the lower abdomen. Bowel movements and sitting down may be painful. Many people with colon cancer first see a doctor because of abdominal pain without knowing the underlying cause.
Fatigue
Fatigue and weakness may be accompanied by unexplained weight loss. The bleeding of the colon, which usually cannot be seen, can cause the weakness. For some people fatigue is the only symptom of colon cancer.
Family History
If possible symptoms appear, it can warn people with risk factors for the disease. A family history of colon cancer and colon polyps increases the risk of developing colon cancer. People who have had intestinal conditions, such as ulcerative colitis or Crohn's disease, have an increased risk of getting colon cancer.
