How Does Colon Cancer Affect the Body?

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Colon Cancer: US Prevalence and Risk (by Gender)

According to the Centers for Disease Control and Prevention, approximately 72,000 men and 69,000 women were diagnosed in 2005; the year for which the most complete data is available. In this same year, about 27,000 men and 26,000 women died from colon cancer. For both men and women, the risk of colon cancer increases with age. Prior to age 50, men and women have a nearly equivalent chance of developing this type of cancer. At age 50 and beyond, men are at higher risk. For instance, for a 70 year old man, the risk of developing colon cancer within the next 10 years is 2 or 3 out of every 100 men; for women, the incidence is 1 or 2 out of every 100 women.

Anatomy and Function of the Colon

The colon is a digestive organ that is located between the small intestine and the rectum. When a person consumes a meal, food passes through the small intestine into the colon. The primary function of the colon is to extract water and nutrients from the food and turn to waste all other food particles. This newly formed waste is eliminated through the rectum. If a person has colon cancer, these functions can be compromised.

How Does Colon Cancer Affect the Body?

The symptoms of colon cancer best reflect how colon cancer affects the body. The most common symptoms, constipation and diarrhea, are fairly common symptoms in the general population of persons without colon cancer. Constipation results when the cancer blocks the passage of stool from the colon to the rectum. Since the colon is responsible for extracting water from food particles, water in the colon can also become blocked in the colon. However, since water can easily pass around the blockage and be excreted through anus, diarrhea may occur. Another symptom is rectal bleeding. This can occur if the colonic tumors start to bleed. The closer the tumor is to the anus, the greater the chance of visible blood loss. Rectal bleeding or tumor blood loss, in general, can result if iron deficiency. This iron deficiency is responsible for the weakness and fatigue that is associated with colon cancer. Abdominal pain can also occur. This pain may result from actually tearing of the colon wall or bowel fluid leaking into the pelvis. Another common symptom is feeling “full” in the colon area. This is most likely a consequence of colon cancer-related constipation.

Summary and Take-Home Messages

In sum, these symptoms answer the question, “How does colon cancer affect the body?” Unfortunately, many of these symptoms are very non-specific and often overlooked and attributed to less serious conditions. Anyone experiencing any of these symptoms should see their doctor. In addition, at age 50, everyone should get regular colorectal checkups. If a person has a family history of colon cancer or other digestive organ cancers, the recommendation is to seek the advice of a doctor to determine if screenings need to begin earlier than 50.


Colorectal Cancer Risk by Age. Centers for Disease Control and Prevention.

Colon Cancer Symptoms. The Mayo Clinic.

Colon Cancer Symptoms. Emedicinehealth.