There are 3 most common compications of colon cancer: obstruction, perforation and direct extension.
Obstructing cancer of the left or right colon is treated by immediate resection in good-risk patients.
An aggressive approach to perforated cancer of the colon is advisable, but anastomosis is often delayed based on the degree of contamination and the health of the bowel. If contamination is severe or if bowel health is compromised, the proximal end is exteriorized as a colostomy (or ileostomy), and the distal end is exteriorized or closed. Secondary anastomosis is performed after inflammation subsides. Alternatively, the anastomosis may be performed and “covered” with a defunctioning loop ileostomy. Closure of a loop ileostomy is a simpler and less morbid procedure than reexploration and closure of an end stoma.
When carcinoma of the colon has spread by contiguity to adjacent viscera such as the small intestine, spleen, kidney, uterus, prostate, or urinary bladder, the involved viscus — or a portion of it — should be resected en bloc with the colon.