Cancer of the colon is cancer of the large intestines or bowels. There is an uncontrollable growth of tumor cells in the lining of this part of the intestines.
The cancer may spread to the walls of the intestines, adjacent structures and to other organs.

There are about 100,000 new cases of colon cancer in the USA each year and about 60,000 deaths. Worldwide there are about 600,000 deaths. The disease affects both women and men.

Risk factors and causes- Cancer of the colon is commoner in industrialized countries where meat consumption is high. Risk factors include:
-History of colon cancer in the family
-Diet high in saturated fat
-Alcohol consumption
-Low fibre diet
-Obesity
-Smoking
-Inflammatory conditions of the colon
-Age over 50


Signs and Symptoms- Signs and symptoms are usually evident when the tumor gets to a certain size. They are often related to the presence of the tumor mass in the area. They are:
-Change in bowels habits
-Blood in the faeces
-Abdominal distension
-Constipation
-Chronic fatigue
-Weight loss
-Anaemia


Diagnosis
If symptoms suggest that a tumor may be present a colonoscopy is performed
Colonoscopy-This is examination of the entire colon using a lighted tube to examine for the presence of lesions or growths. A biopsy of any abnormal tissue can be done at the same time making it a preferred diagnostic procedure.
It is also the standard test used to screen for colon cancer.
Biopsy- If a tumor is spotted, a biopsy is done. In this investigation a specimen of any lesions or tissue is obtained to examine for the presence of cancer cells. This is the most definitive diagnostic procedure, as the tumor can then be identified as either benign or malignant.
Barium enema- This is a procedure in which a barium compound is instilled in the rectum filling the rectum. X-rays are then taken and the colon can be viewed through its outline.
Digital rectal examination (DRE)- In this procedure a physician examines the anus and the rectum and prostate using a gloved finger. Stool for occult blood can be done at the same time using any stool left on the glove.
Blood tests- Another investigation is blood tests for tumor markers. If cancer is present the protein antigen is elevated

Prevention of colon cancer
Consumption of red meat seems to contribute to the higher incidence of colon cancer in industrialized countries. Developing a healthy eating pattern is therefore an important preventive action. Other preventive measures include:
-Regular screening for those at risk
-Keeping physically active
-Avoiding tobacco
-Keeping weight within limits
-Controlling alcohol consumption
-A high fibre diet

Treatment
Surgery- This is the removal of the section of the colon affected, along with the blood supply and lymph nodes. Following this resection either an anastomosis or a colostomy would be performed
Anastomosis- In this procedure the ends of the remaining colon are joined together by a reconstructive procedure.
Colostomy- If the reconstructive procedure is not possible or is too risky, a colostomy is performed. This involves bringing the end of the remaining colon through the abdomen and sewing it to the skin. A stoma is created through which faces is excreted. This may be temporary or permanent.

Radiation- Radiation is used following surgery to remove the tumor cells not removed by resection or when there is metastasis.

Chemotherapy- This is the use of anti-cancer drugs. Chemotherapy is used when there is a risk that the tumor will return. It is also used for stage 4 cancers when surgery is not possible. Other possible treatments are Adjuvant therapy and Alternative therapy.