Rectum, cancer of

A cancerous tumour in the rectum. The cause is unknown, but dietary factors and genetic factors are thought to play a part. It is more common between ages 50 and 70. Early symptoms are rectal bleeding during defecation and diarrhoea or constipation. Later, pain may occur. Left untreated, the cancer may eventually cause severe bleeding and pain and block the intestine. It may also spread to other organs. The cancer may be detected by a rectal examination and confirmed with proctoscopy or sigmoidoscopy and biopsy. Treatment is usually with surgery. For a tumour in the upper rectum, the affected area and the last part of the colon are removed and the 2 free ends of the intestine are sewn together. To promote healing, a temporary colostomy may be made. For a growth in the lower rectum, the entire rectum and anus are removed. Because there is no outlet for faeces, a permanent colostomy is created. Radiotherapy and anticancer drugs may be used in addition to or instead of surgery. Up to 40 per cent of people treated for rectal cancer live for 10 years or more.