Symptoms include local pain hemorrhage and obstruction. Prior to the onset of severe symptoms, the tumor can usually be detected by a routine rectal examination and by sigmoidoscopy. For this reason the American Cancer Society recommends an annual rectal examination and sigmoidoscopy every three to five years for all people over the age of 50. Colon cancer has been linked to exposure to environmental carcinogens, a diet high in meat fat, protein and total energy content, cholesterol metabolites, calcium deficiency and genetic factors. Conversely, the incidence of colon cancer inversely correlates with a diet high in fiber content, fruit and vegetables.
Tissue biopsy is required to confirm positive rectal exam or sigmoidoscopy findings.
The only cure for colon cancer is surgery with complete removal of the tumor and infected lymph nodes. Prior to surgery, colonoscopy is usually performed to determint the exact location of the tumor and potential presence of smaller adjacent tumors.