by Marmee Cosico

Created on: December 04, 2009   Last Updated: December 05, 2009

Colon cancer is the "second" leading cause of cancer death in the US today. It accounts for 20% of cancer-related deaths among Americans. The incidence of the disease increases with advancing age, and 90% of cases occur after the age of 50 years. The incidence of colorectal cancer is similar among men and women until the age of 50 years, but later on above 50 years of age the incidence becomes higher in men. In 2000, there were an estimated 130,200 new cases and 56,300 deaths while in 2002, approximately 148,000 new cases of colorectal cancer (colon, 107,000; rectum, 41,000) and 57,000 deaths.

Approximately 75% of colorectal cancers (so-called "sporadic" cancer) occur among individuals without any obvious risk factors. The remaining cases occur in individuals with three or more relatives with colon cancer, one of whom is a first degree relative; one or more cases diagnosed before age 50; and involvement of at least two generations. Environmental factors include an increased prevalence in developed countries, urban areas, advantaged socioeconomic groups, increased risk in patients with coronary artery disease (increased cholesterol), correlation of risk with low fiber, high animal fat diets; decreased risk with long term dietary calcium supplementation and daily aspirin ingestion patients with history of breast or gynecologic cancer, familial polyposis syndromes, > 10 year history of ulcerative colitis or Crohn's colitis and > 15 year history of ureterosigmoidoscopy.

The most common presenting symptomsin patients with colorectal cancer include a "change in bowel habits" such as diarrhea , constipation, a feeling that the bowel does not empty completely, stools that are narrower in caliber than usual accompanied with bright red blood in the stool or "melenic stools". Other signs include general abdominal discomfort such as frequent gas pains, bloating, fullness, cramps. Also unexplained weight loss, fatigue and vomiting should be noted. Tumors in the cecum and ascending colon frequently presents with symptoms of anemia, occult blood in stool and laboratory studies show iron deficiency anemia. Ulceration of the tumor often leads to chronic blood loss in the stool without an appreciable change in the stool color. Cancers occuring in the left side of the colon generally cause constipation alternating with diarrhea, rectal bleeding and abdominal or back pain.

Prevention. Early detection of colon carcinoma may be done by routine screening of stool for occult blood (Hemoccult II, Colo-Test). Tests for fecal blood are frequently positive in persons with colonic neoplasms. Annual digital exam and fecal occult blood testing is recommended for patients over age 40 and screening flexible sigmoidoscopy every 3 years after age 50. It should be noted that screening of asymptomatic persons allows earlier detection of colon cancer and achieves greater resectability rate. Finally, a more intensive evaluation of first degree relatives of patients with colon carcinoma frequently includes screening air contrast barium enema or colonoscopy after age 40.

For More Information www.harrisonsonline.com

National Polyp Study on Colon Cancer www.ncbi.nlm.nih.gov/pubmed/8247072

www.ncbi.nlm.nih.gov/pubmed/15239144

WHO's Classification of Colorectal Cancer www.ncbi.nlm.nih.gov/pubmed/17204026

Cancer Facts & Figures,2002 www.cancer.org

College of American Pathologists www.cap.org/

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