SEER Logo

SEER Training Modules

ICD-O-3 Site Codes

Related Adjectives

  • Colon—colo, colono-
  • Rectum—rectal, recto-
  • Anus—procto-, ano-
  • Colon and rectum—large bowel, large intestine, colorectal
ICD-O-2/3 Term
C18.0 Cecum
C18.1 Appendix
C18.2 Ascending colon; Right colon
C18.3 Hepatic flexure of colon
C18.4 Transverse colon
C18.5 Splenic flexure of colon
C18.6 Descending colon; Left colon
C18.7 Sigmoid colon
C18.8 Overlapping lesion of colon
C18.9 Colon, NOS
ICD-O-2/3 Term
Rectosigmoid junction
C19.9 Rectosigmoid junction
ICD-O-2/3 Term
Rectum
C20.9 Rectum, NOS
ICD-O-2/3 Term
Anus and Anal canal
C21.0 Anus, NOS (excludes Skin of anus and Perianal skin C44.5)
C21.1 Anal canal
C21.2 Cloacogenic zone
C21.8 Overlapping lesion of rectum, anus and anal canal

Each ICD-O four-digit sub site within the colon and rectum is considered a separate primary site.