Colorectal Cancer
Incidence and mortality
Colorectal cancer ranks third on the list of major cancer types worldwide, in terms of both incidence and mortality. In the UK, about 36,000 new cases of colorectal are diagnosed annually. Moreover, the disease is responsible for about 16,000 deaths each year in the UK alone (Cancer Research UK large bowel cancer statistics).
Colorectal cancer comprises all cancers of the large bowel, excepting those of the anal canal. Most colorectal cancers originate from pre-existing polyps (or adenomas). The incidence of these benign lesions increases with age, reaching about 75% in those over the age of 75 years. The vast majority of colorectal cancers occur spontaneously, with only about 5% of new cases due to hereditary syndromes.
Symptomatology
The symptoms of colorectal cancer include abdominal pain, rectal bleeding and altered bowel habits.
Treatment
The primary treatment approach for colorectal cancer is surgery. A large section of bowel adjacent to the tumour is removed to ensure that no cancer cells remain. Adjuvant therapies are sometimes used in combination with surgery. Chemotherapy, for instance, has shown to improve the survival of patients with advanced stages of the disease (metastases) or with a high recurrence risk.
Survival
The 5-year survival rate depends on the stage of the tumour at the time of diagnosis. According to Duke's staging system, the best case scenario is when the tumour is confined to the mucosa (5-year survival = 90%). In contrast, if distant metastases are detected, the estimated 5-year survival rate is less than 1%.