CS Extension: Colon

Note 1: Ignore intraluminal extension to adjacent segment(s) of colon/rectum or to the ileum from the cecum; codedepth of invasion or extracolonic spread as indicated.

Note 2: A tumor nodule in the pericolic adipose tissue of a primary carcinoma without histologic evidence of residual lymph node in the nodule is classified as a regional lymph node metastasis if the nodule has the form and smooth contour of a lymph node, or if the contour is not described. If the nodule has an irregular contour, it should be coded in CS Extension as code 45.

Note 3: Codes 60-80 are used for contiguous extension from the site of origin. Discontinuous involvement is coded in CS Mets at DX.

Code Description TNM SS77 SS2000
00 In situ; noninvasive; intraepithelial Tis IS IS
05 (Adeno)carcinoma in a polyp or adenoma, noninvasive Tis IS IS
10 Invasive tumor confined to mucosa, NOS (including intramucosal, NOS) T1 L L
11 Lamina propria, including lamina propria in the stalk of a polyp T1 L L
12 Muscularis mucosae, including muscularis mucosae in the stalk of a polyp T1 L L
13 Confined to head of polyp, NOS T1 L L
14 Confined to stalk of polyp, NOS T1 L L
15 Invasive tumor in polyp, NOS T1 L L
16 Invades submucosa (superficial invasion), including submucosa in the stalk of a polyp T1 L L
20 Muscularis propria invaded T2 L L
30 Localized, NOS
Confined to colon, NOS
T1 L L
  • Extension through wall, NOS
  • Invasion through muscularis propria or muscularis, NOS
  • Non-peritonealized pericolic tissues invaded
  • Perimuscular tissue invaded
  • Subserosal tissue/(sub)serosal fat invaded
  • Transmural, NOS
T3 L L
42 Fat, NOS T3 RE RE
45 Extension to:
  • All colon sites:
  • Adjacent tissue(s), NOS
  • Connective tissue
  • Mesenteric fat
  • Mesentery
  • Mesocolon
  • Pericolic fat
  • Ascending and descending colon
  • Retroperitoneal fat
  • Transverse colon/flexures
  • Gastrocolic ligament
  • Greater omentum
46 Adherent to other organs or structures, but no microscopic tumor found in adhesion(s) T3 RE RE
50 Invasion of/through serosa (mesothelium) (visceral peritoneum) T4 RE RE
55 Any of [(42) to (45)] + (50) T4 RE RE
57 Adherent to other organs or structures, NOS T4 RE RE
  • All colon sites:
    • Small intestine
  • Cecum and appendix:
    • Greater omentum
  • Ascending colon:
    • Greater omentum
    • Liver, right lobe
  • Tranverse colon and flexures:
    • Gallbladder/bile ducts
    • Kidney
    • Liver
    • Pancreas
    • Spleen
    • Stomach
  • Descending colon:
    • Greater omentum
    • Pelvic wall
    • Spleen
  • Sigmoid colon:
    • Greater omentum
    • Pelvic wall
65 All colon sites:
  • Abdominal wall
  • Retroperitoneum (excluding fat)
  • Ascending colon:
    • Right kidney
    • Right ureter
  • Descending colon:
    • Left kidney
    • Left ureter
70 Cecum, appendix, ascending, descending and sigmoid colon:
  • Fallopian tube
  • Ovary
  • Uterus
T4 D D
75 All colon sites unless otherwise stated above:
  • Adrenal (suprarenal) gland
  • Bladder
  • Diaphragm
  • Fistula to skin
  • Gallbladder
  • Other segment(s) of colon via serosa
T4 D D
  • Further contiguous extension:
    • Cecum and appendix:
    • Kidney
    • Liver
    • Ureter
    • Transverse colon and flexures:
    • Ureter
    • Sigmoid colon:
    • Cul de sac (rectouterine pouch)
    • Ureter
  • Other contiguous extension
T4 D D
95 No evidence of primary tumor T0 U U
  • Unknown extension
  • Primary tumor cannot be assessed
  • Not documented in patient record
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