Cancer of the rectum grows in an easily distensible part of the lower bowel, and accordingly obstructive symptoms virtually never occur. Instead the symptoms are of bowel irregularity, blood in the feces, and a constant urge to defecate, together with tenesmus, the feeling of incomplete bowel evacuation because of the presence of this often quite bulky tumor.
The diagnosis is easily established by simple digital examination. The tumor tends to grow relatively slowly and to spread more by local infiltration into the badder and other pelvic organs than by metastasizing widely.
When metastases are present the usual first site is in the liver. The only effective treatment is by surgical removal by the standart operative procedure known as a abdominoperineal excision. This removes the whole lower sigmoid and lymph nodes, the rectum, and the anus, and leaves the patient with a permanent colostomy.
With modern colostomy appliances and some dietary adjustments the colostomy patient can live an active and busy life with no social problems.
Preoperative radiotherapy is of some value in rectal cancer in shrinking the size of the tumor mass and rending border line situations operable. It is of undoubted value in controlling any recurrences in the perienal scar. Because rectal cancer tend to be relatively slow growing, chemotherapy is of very limited value.
Cancer of the anus is usually a squamous epithelioma, and, similar tumors elsewhere, it can often be cured by radiotherapy alone. Acerbate therapy has recently been reported to be effective.