Colon surgery is the most common treatment for colon cancer. In ideal situations, where the cancer is found at a very early stage, a doctor can remove the tumor with a colonoscope. Most of the time however, colon surgery is required.
When cancer is identified at a later stage, treatment usually requires the kind of colon surgery you tend to think of when you hear the word "surgery."
The standard procedure is called a surgical resection. In a resection, a surgeon makes an incision in the abdomen, removes the tumor, then reconnects the colon so it's one piece again -- one long, healthy piece. (Find a colon surgeon.)
An ostomy is another type of colon surgery and is basically a detour for your intestines. Waste normally travels through the colon into the rectum, then is released through the anus during defecation.
An ostomy bypasses the rectum altogether and instead, waste material leaves the intestine through a port in the abdomen, and moves into a colostomy bag on the outside of the body. Some ostomies are permanent. Others are temporary detours that give part of your body a chance to heal before you use it again.
Source: "Detailed Guide: Colon and Rectum Cancer: How Is Colorectal Cancer Treated?" American Cancer Society 22 Feb. 2006. Accessed 21 Jul. 2007 [http://www.cancer.org/docroot/CRI/content/CRI_2_4_4x_How_is_colorectal_cancer_treated_10.asp?sitearea=].