Primary tumor (T) | |||
T category | T criteria | ||
TX | Primary tumor cannot be assessed | ||
T0 | No evidence of primary tumor | ||
Tis | Carcinoma in situ, intramucosal carcinoma (involvement of lamina propria with no extension through muscularis mucosae) | ||
T1 | Tumor invades the submucosa (through the muscularis mucosa but not into the muscularis propria) | ||
T2 | Tumor invades the muscularis propria | ||
T3 | Tumor invades through the muscularis propria into pericolorectal tissues | ||
T4 | Tumor invades* the visceral peritoneum or invades or adheres¶ to adjacent organ or structure | ||
T4a | Tumor invades* through the visceral peritoneum (including gross perforation of the bowel through tumor and continuous invasion of tumor through areas of inflammation to the surface of the visceral peritoneum) | ||
T4b | Tumor directly invades* or adheres¶ to adjacent organs or structures | ||
* Direct invasion in T4 includes invasion of other organs or other segments of the colorectum as a result of direct extension through the serosa, as confirmed on microscopic examination (for example, invasion of the sigmoid colon by a carcinoma of the cecum) or, for cancers in a retroperitoneal or subperitoneal location, direct invasion of other organs or structures by virtue of extension beyond the muscularis propria (ie, respectively, a tumor on the posterior wall of the descending colon invading the left kidney or lateral abdominal wall; or a mid or distal rectal cancer with invasion of prostate, seminal vesicles, cervix, or vagina). ¶ Tumor that is adherent to other organs or structures, grossly, is classified cT4b. However, if no tumor is present in the adhesion, microscopically, the classification should be pT1-4a depending on the anatomical depth of wall invasion. The V and L classification should be used to identify the presence or absence of vascular or lymphatic invasion whereas the PN prognostic factor should be used for perineural invasion. | |||
Regional lymph nodes (N) | |||
N category | N criteria | ||
NX | Regional lymph nodes cannot be assessed | ||
N0 | No regional lymph node metastasis | ||
N1 | One to three regional lymph nodes are positive (tumor in lymph nodes measuring ≥0.2 mm), or any number of tumor deposits are present and all identifiable lymph nodes are negative | ||
N1a | One regional lymph node is positive | ||
N1b | Two or three regional lymph nodes are positive | ||
N1c | No regional lymph nodes are positive, but there are tumor deposits in the:
| ||
N2 | Four or more regional nodes are positive | ||
N2a | Four to six regional lymph nodes are positive | ||
N2b | Seven or more regional lymph nodes are positive | ||
Distant metastasis (M) | |||
M category | M criteria | ||
M0 | No distant metastasis by imaging, etc; no evidence of tumor in distant sites or organs. (This category is not assigned by pathologists.) | ||
M1 | Metastasis to one or more distant sites or organs or peritoneal metastasis is identified | ||
M1a | Metastasis to one site or organ is identified without peritoneal metastasis | ||
M1b | Metastasis to two or more sites or organs is identified without peritoneal metastasis | ||
M1c | Metastasis to the peritoneal surface is identified alone or with other site or organ metastases | ||
Prognostic stage groups | |||
When T is... | And N is... | And M is... | Then the stage group is... |
Tis | N0 | M0 | 0 |
T1, T2 | N0 | M0 | I |
T3 | N0 | M0 | IIA |
T4a | N0 | M0 | IIB |
T4b | N0 | M0 | IIC |
T1-T2 | N1/N1c | M0 | IIIA |
T1 | N2a | M0 | IIIA |
T3-T4a | N1/N1c | M0 | IIIB |
T2-T3 | N2a | M0 | IIIB |
T1-T2 | N2b | M0 | IIIB |
T4a | N2a | M0 | IIIC |
T3-T4a | N2b | M0 | IIIC |
T4b | N1-N2 | M0 | IIIC |
Any T | Any N | M1a | IVA |
Any T | Any N | M1b | IVB |
Any T | Any N | M1c | IVC |
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