9. Colorectal cancer

Synopsis Colorectal cancer is the leading cause, after lung cancer, of death from cancer in Australia. About 50% of colorectal cancers are attributed to dietary factors and about 15%‐‐20% to genetic factors, including high risK familial syndromes. The most common presenting symptoms are rectal bleeding (left‐sided cancers) and iron‐deficiency anaemia (right‐sided cancers). Patients with suggestive symptoms should have a digital rectal examination, followed by sigmoidoscopy and biopsy if a rectal lesion is suspected, or colonoscopy if colon cancer is suspected. Treatment of most colorectal cancers is segmental resection with a wide resection margin; the role of adjuvant therapy is still being refined. Screening with annual (or biennial) faecal occult blood tests is recommended for people over 50 years without symptoms and with average or slightly above average risk; more intensive, earlier screening is recommended for those with greater risk.