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Colon tumor

Other

Staging of colonic carcinoma

Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 2 June 2012, last major update May 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Previous staging systems are 1932 Dukes staging system for rectal carcinomas applied to colon carcinomas or 1954 Astler-Coller modification of Dukes staging
● Appendiceal adenocarcinomas or anal carcinomas are classified differently
● Examination of all mesentery may be necessary to ensure correct pN status in pN1 cases (Mod Pathol 2004;17:402)
● 7th Edition of AJCC cancer staging is discussed below

Dukes staging (not currently used)
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● Designed for rectum, but was often applied to entire colon

● A: growth limited to wall of rectum
● B: extension of growth to extra rectal tissues, no metastasis to regional lymph nodes
● C: metastases in regional lymph nodes, modified in 1935 to C1 and C2 stages
● C1: metastases to regional lymph nodes
● C2: metastases to lymph nodes at point of mesenteric blood vessel ligature
● D: distant metastases (not part of original classification)

Astler-Coller classification (not currently used)
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● A: lesion limited to mucosa
● B1: lesion involves muscularis propria but does not penetrate through it
● B2: lesion penetrates through the muscularis propria
● C1: metastatic tumor in lymph nodes but the tumor itself is still confined to the bowel wall
● C2: metastatic tumor in lymph nodes and tumor itself has penetrated through the entire bowel wall

● Per Rosai, call stage B if no identifiable muscularis propria layer between tumor and serosal surface

TNM staging of colorectal carcinoma (AJCC-7th Edition)

Primary tumor (T)
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● TX: primary tumor cannot be assessed
● T0: no evidence of primary tumor
● Tis: carcinoma in situ: i.e. intraepithelial or invasion of lamina propria, but not through muscularis mucosa into submucosa
● T1: tumor invades submucosa
● T2: tumor invades muscularis propria
● T3: tumor invades through the muscularis propria into the peri-colorectal tissues
● T4a: tumor penetrates to the surface of the visceral peritoneum
● T4b: tumor directly invades or is adherent to other organs or structures

Notes:
● Tis includes cancer cells confined within the glandular basement membrane (intraepithelial) or mucosal lamina propria (intramucosal) with no extension through the muscularis mucosae into the sub-mucosa
● 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 sub peritoneal location, direct invasion of other organs or structures by virtue of extension beyond the muscularis propria (that is, 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 classifications should be used to identify the presence or absence of vascular or lymphatic invasion, whereas the PN site-specific factor should be used for perineural invasion

Regional lymph nodes (N)
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● NX: regional lymph nodes cannot be assessed
● N0: no regional lymph node metastasis
● N1: metastasis in 1-3 regional lymph nodes
● N1a: metastasis in one regional lymph node
● N1b: metastasis in 2-3 regional lymph nodes
● N1c: tumor deposit(s) in the subserosa, mesentery or non-peritonealized pericolic or perirectal tissues without regional nodal metastasis
● N2: metastasis in 4 or more regional lymph nodes
● N2a: metastasis in 4-6 regional lymph nodes
● N2b: metastasis in 7 or more regional lymph nodes

Notes:
● A satellite peritumoral nodule in the pericolorectal adipose tissue of a primary carcinoma without histologic evidence of residual lymph node in the nodule may represent discontinuous spread, venous invasion with extravascular spread (V1/2) or a totally replaced lymph node (N1/2)
● Replaced nodes should be counted separately as positive nodes in the N category, whereas discontinuous spread or venous invasion should be classified and counted in the Site-Specific Factor category Tumor Deposits

● 10-15 lymph nodes are required for accurate staging (Eur J Cancer 2005;41:2071)
● Increasing number of negative nodes in Stage IIIB/C disease has favorable prognostic value (J Clin Oncol 2006;24:3570)
● Sentinel node staging with cytokeratin is highly accurate for clusters of tumor cells; isolated cytokeratin+ cells may not represent tumor (Arch Pathol Lab Med 2003;127:673, Arch Pathol Lab Med 2000;124:1759)

● Most lymph nodes with metastases are 5 mm or less
● Nodal metastases often have involvement of surrounding veins
● Presence of micrometastases currently has no definitive value

Distant Metastasis (M)
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● M0: no distant metastasis
● M1: distant metastasis
● M1a: metastasis confined to one organ or site (e.g. liver, lung, ovary and non-regional node)
● M1b: metastases in more than one organ / site or the peritoneum

Stage grouping and survival
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● Note: 5 year survival is based on AJCC 6th classification (J Natl Cancer Inst 2004;96:1420)

● Stage 0: Tis N0 M0 (100%)
● Stage I: T1-T2 N0 M0 (93%)
● Stage IIA: T3 N0 M0 (85%)
● Stage IIB: T4a N0 M0 (72%)
● Stage IIC: T4b N0 M0 (72%)
● Stage IIIA: T1-T2 N1/N1c M0 or T1 N2a M0 (83%) ● Stage IIIB: T3-T4a N1/N1c M0 or T2-T3 N2a M0 or T1-T2 N2b M0 (64%)
● Stage IIIC: T4a N2a M0 or T3-T4a N2b M0 or T4b N1-N2 M0 (44%)
● Stage IVA: any T, any N, M1a (8%)
● Stage IVB: any T, any N, M1b (8%)

Residual tumor (R factor)
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● Tumor remaining in patient after surgical resection

● RX: presence of residual tumor cannot be assessed
● R0: no residual tumor; margins histologically negative
● R1: microscopic residual tumor (corresponds to positive resection margin)
● R2: macroscopic residual tumor (either positive margins or gross disease remains after resection)

● References: Arch Pathol Lab Med 2006;130:318 (staging problems)

Diagrams
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Staging related diagrams

Gross images-sentinel lymph nodes
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Micro images-sentinel lymph nodes
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End of Colon tumor > Other > Staging of colonic carcinoma

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