Surgery can be done for any of several reasons. It is often done to reach more than one of these goals:
Preventive (prophylactic) Surgery
Preventive surgery is done to remove body tissue that is not malignant (cancerous) but is likely to become malignant. For example, this type of surgery may be used if you have a pre-cancerous condition such as polyps in the colon.
read more at http://www.cancer.org/docroot/ETO/content/ETO_1_2X_Surgery.asp