Colon Cancer Stages - Version 1.0 Introduction Colon cancer stages determine the very nature of the disease and the rate at which it has spread in the body and hence, deteriorated it. Colon cancer stages determine the very nature of the disease and the rate at which it has spread in the body and hence, deteriorated it. It must be understood that once the person has been diagnosed with colon cancer, he is made to undergo various tests which determine the stage of the colon cancer. This process is known as “staging” and the diagnostic methods involved here include CT scan or a CAT scan, PET scan, MRI, blood tests, x ray and lymph node biopsy. http://coloncancerstages.org.