According to the Centers for Medicare and Medicaid Services (CMS), the ICD-9 Codes for colon cancer begin with 209. The numbers after 209 are determined by the malignancy of the tumor and its location.
According to CMS, malignant tumors in the colon have ICD-9 Codes that begin 209.1; benign tumors in the colon have ICD-9 Codes that begin 209.5. The fifth number is a 3 if the tumor is in the ascending colon, a 4 if it is in the transverse colon, a 5 if it is in the descending colon and a 6 if it is in the sigmoid colon. For example, a benign tumor of the sigmoid colon has the ICD-9 Code 209.56.