Colorectal cancer: early diagnosis and predisposing causes

Colorectal cancer is a leading cause of cancer-related morbidity and mortality in the western world. It is the third commonest cancer (after lung and breast) in the UK with >35,000 new cases diagnosed every year. In general, cancer of the large bowel is a disease of old age, with >80% of cases arising in those aged >60 years; cases arising in those aged <50 years are usually associated with inherited genetic predisposition. Incidence is equal between the sexes up to the age of 40 years, but is higher in males in older age groups. Historically, the left side of the colon and the rectum accounted for most colorectal cancers, but this preponderance has fallen from 75% in the 1950s to about 60% in recent years. This contribution discusses the pathology, genetics, early diagnosis and predisposing conditions of colorectal cancer.