Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ: intraepithelial or invasion of the lamina propria*
• T1: Tumor invades submucosa
• T2: Tumor invades muscularis propria
• T3: Tumor invades through the muscularis propria into the subserosa, or into nonperitonealized pericolic or perirectal tissues
• T4: Tumor directly invades other organs or structures, and/or perforates the visceral peritoneum**,***

* [Note: Tis includes cancer cells confined within the glandular basement membrane (intraepithelial) or lamina propria (intramucosal) with no extension through the muscularis mucosae into the submucosa.]

** [Note: Direct invasion in T4 includes invasion of other segments of the colorectum by way of the serosa; for example, invasion of the sigmoid colon by a carcinoma of the cecum.]

*** [Note: Tumor that is adherent to other organs or structures, macroscopically, is classified T4. However, if no tumor is present in the adhesion, microscopically, the classification should be pT3. The V and L substaging should be used to identify the presence or absence of vascular or lymphatic invasion.]

Regional lymph nodes (N)

• NX: Regional lymph nodes cannot be assessed
• N0: No regional lymph node metastasis
• N1: Metastasis in 1 to 3 regional lymph nodes
• N2: Metastasis in 4 or more regional lymph nodes

 [Note: A tumor nodule in the pericolorectal adipose tissue of a primary carcinoma without histologic evidence of residual lymph node in the nodule is classified in the pN category as a regional lymph node metastasis if the nodule has the form and smooth contour of a lymph node. If the nodule has an irregular contour, it should be classified in the T category and also coded as V1 (microscopic venous invasion) or as V2 (if it was grossly evident), because there is a strong likelihood that is represents venous invasion.]

Distant metastasis (M)

• MX: Distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Stage 0

• Tis, N0, M0

Stage I

• T1, N0, M0
• T2, N0, M0

Stage IIA

• T3, N0, M0

Stage IIB

• T4, N0, M0

Stage IIIA

• T1, N1, M0
• T2, N1, M0

Stage IIIB

• T3, N1, M0
• T4, N1, M0

Stage IIIC

• Any T, N2, M0

Stage IV

• Any T, any N, M1