Peter G. Rossos MD, FRCP(C)
Elaine Yeung MD
Division of Gastroenterology, University Health Network
University of Toronto, Toronto, ON.

Introduction
Colorectal cancer (CRC) is the third most common cause of cancer and second leading cause of cancer death in Canada. It is estimated that there were 17,200 new cases and 6,400 deaths from colorectal cancer in Canada in 2001. When both women and men are considered together, colorectal cancer is the second most frequent cause of death from cancer among Canadians.¹ Most CRC occurs in average risk individuals for whom there are no accepted guidelines for screening.² Higher risk categories include those who have a family history of CRC, a personal history of CRC, colonic adenomas or inflammatory bowel disease, and the familial syndromes including familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC).³ This discussion will focus on average risk older adults, who comprise almost all CRC cases in patients 65 years of age or older.

Epidemiologic Considerations
Although age-standardized incidence and mortality rates have been declining for CRC since 1985, the number of new cases has continued to rise steadily and significantly among both men and women as a result of the growth and aging of the population. Recent data from the National Cancer Institute of Canada is displayed in Figures 1 and 2.

Nariman Malik, BSc

Diverticular disease of the colon had been a rare clinical entity before the twentieth century. Currently, diverticulosis is the most common condition affecting the intestine.¹ The incidence of diverticular disease increases with age from approximately 9% in those younger than 50 to 50% in those over the age of 70.² Diverticular disease is almost exclusively seen in populations that consume low fibre diets such as those common in Western society. Interestingly, these conditions are less common in vegetarians than in non-vegetarians. There is no associated risk with smoking, caffeine, or alcohol use.³

A diverticulum is defined as a sac-like protrusion of the colonic wall. Colonic diverticuli are formed by the herniation of the mucosa and submucosa through the muscularis mucosa. They tend to develop at points where the vasa recta penetrates the circular muscle layer.

Diverticular disease is a spectrum of diseases that encompass three clinical multi-faceted conditions: diverticulosis, diverticulitis, and diverticular bleeding. Each condition has a unique set of presenting symptoms and an individualized course of management (see Table 1).