Colorectal Cancer: Epidemiology, Risk Factors, and Health ServicesFarin Amersi, M.D.,1Michelle Agustin, M.P.H.,2andClifford Y. Ko, M.D.2,3Author informationCopyright and License informationGo to:ABSTRACTColorectal carcinoma is the third most common cancer in the United States in both men and women but still remains the second leading cause of cancer-related deaths. The risk of developing colorectal cancer increases with age. Additional risk factors include family history of colorectal cancer, heredity conditions such as polyposis and hereditary nonpolyposis colorectal cancer, and personal history of inflammatory bowel disease, polyps, and cancers. Health services is a new scientific discipline that examines the quality of care, often at the population level, and may examine parts or the entire spectrum of care.Keywords:Colorectal cancer, epidemiology, risk factorsThis article addresses the epidemiology of colorectal cancer, including the described risk factors for its development. In addition, we provide a brief discussion of the health services issues as they relate to colorectal cancer. Both topics are essential public health factors regarding improving the care and outcomes for this cancer.Colorectal carcinoma is the third most common cancer in the United States in both men and women but still remains the second leading cause of cancer-related deaths. Worldwide, colorectal cancer is the fourth most common cancer and affects both men and women equally. In 2003, more than 146,000 cases of colorectal cancer were diagnosed in the United States, and the American Cancer Society estimated that ~56,730 would die from this disease.1The substantial mortality associated with this cancer makes it the leading cause of gastrointestinal cancer deaths. In adults in the United States, the incidence of colorectal cancer and mortality rates from this disease have steadily declined over the past two decades.2,3The lifetime probability of developing colorectal cancer is 1 in 17 for men and 1 in 18 for women.4Although large differences exist in survival depending on the stage of the disease, if colorectal cancer is diagnosed at an early stage, 5-year survival rates have been reported to be as high as 90%.5,6,5Go to:EPIDEMIOLOGYAgeThe risk of developing colorectal cancer increases with advancing age. More than 90% of the people diagnosed with the disease are older than 50, with the average age at the time of diagnosis being 64. In the United States it is the most common cancer in the population older than 75. People between the ages of 65 and 85 are six times more likely to develop colorectal cancer than people younger than 50.8Patients older than 70 present mostly with early-stage disease, whereas younger patients, usually in their 40s, present with much more aggressive disease for a given stage of presentation.9GenderThe role of gender in the development of colorectal cancer remains unclear. In the United States and worldwide, the incidence in men and women is equal.10In a study by McArdle and Hole, looking at outcomes in 3200 patients after colorectal surgery for colorectal cancer, female patients tended to be older at presentation, with 40% of the patients being over the age of 75, compared with 30% of male patients presenting over the age of 75.11Women had more right-sided tumors, whereas men had more tumors in the left side of the colon. Although women presented more in an emergency setting than male patients, no differences in postoperative mortality were seen between the sexes; however, the overall 5-year survival and disease-free survival following curative resection were significantly higher in women than men, 55.2% versus 49% (p90%) from patients with germline mutations in the MMR genes. Six different proteins are required for the complete MMR system: hMSH2, hMLH1, hPMS1, hPMS2, hMSH3, and hMSH6. The geneshMSH2andhMLH1have been thought to account for most of the mutations seen in patients with HNPCC.39HNPCC constitutes ~5% to 10% of all colorectal cancers and confers up to an 80% lifetime risk of developing colon cancer, a 61% risk of developing endometrial cancer, a 9% risk for ovarian cancer, and a