Principles of Tumor Classification


Premalignant

Epithelial tumors

Adenomas

Tubular

Tubulovillous

Villous

Low-grade dysplasia

High-grade dysplasia

Serrated lesions

Hyperplastic polyp

Sessile serrated lesion/polyp/adenoma

Traditional serrated adenoma

Sessile serrated adenoma with conventional dysplasia

Hamartomas

Cowden-associated polyp

Juvenile polyp

Peutz-Jeghers polyp




Table 23.2
Malignant tumors of the colon and rectum









































Carcinomas

Adenocarcinoma

Cribriform (comedo type)

Medullary carcinoma

Micropapillary

Mucinous carcinoma

Signet ring carcinoma

Serrated adenocarcinoma

Adenosquamous carcinoma

Squamous cell carcinoma

Spindle cell carcinoma

Undifferentiated carcinoma

Neuroendocrine neoplasms

Neuroendocrine tumors (Grade 1 and Grade 2)

Neuroendocrine carcinoma

Large-cell carcinoma

Small-cell carcinoma

Mixed adenoneuroendocrine carcinoma



Table 23.3
Mesenchymal tumors of the colon and rectum





















Leiomyoma

Lipoma

Angiosarcoma

Gastrointestinal stromal tumor

Kaposi sarcoma

Leiomyosarcoma

Lymphomas

Secondary tumors/metastatic tumors



Table 23.4
Tumors of the anal canal



























































Premalignant

Epithelial tumors

Anal intraepithelial neoplasia, low grade

Anal intraepithelial neoplasia, high-grade

Paget disease of the anus

Malignant carcinoma

Squamous cell carcinoma

Verrucous carcinoma

Undifferentiated carcinoma

Adenocarcinoma

Mucinous adenocarcinoma

Neuroendocrine neoplasms

Neuroendocrine tumors (Grade 1 and Grade 2)

Neuroendocrine carcinoma

Large-cell carcinoma

Small-cell carcinoma

Mixed adenoneuroendocrine carcinoma

Mesenchymal tumors

Leiomyoma

Lipoma

Angiosarcoma

Gastrointestinal stromal tumor

Kaposi sarcoma

Leiomyosarcoma

Lymphomas

Secondary tumors/metastatic tumors

Anal melanoma



Table 23.5
Tumors of the anal margin (perianal tumors)













These tumors are best regarded as variants of skin cancer and are treated and staged similar to their skin counterparts

Squamous cell carcinoma

Basal cell carcinoma

Melanoma



23.1.1 UICC/AJCC TNM Classification of Tumors of the Colon, Rectum, Anus and Perianal Skin


Staging is the assessment of the degree of spread of a tumor. The staging can be clinical or pathological.

Clinical staging is used alone in the following circumstances:



  • When there is no surgical treatment


  • When adjuvant treatment is administered before surgery


  • When there are insufficient data to stage the patient pathologically

Pathological staging of colorectal cancer was historically undertaken by a number of different systems. The two used in Europe were the TNM and the older Dukes classification. Originally the Dukes classification used three stages: A, B, and C [4]. The latter was subsequently modified into stages C1 and C2, with the addition of a fourth stage, stage D [5] (see Table 23.6). The UICC and AJCC recently introduced the TNM staging system, which uses four stages (stages I–IV). The anatomic extent of cancer is described by assessing three components:


Table 23.6
Dukes staging


















Dukes A

Tumor penetrates into, but not through, the muscularis propria (the muscular layer) of the bowel wall

Dukes B

Tumor penetrates through the muscularis propria of the bowel wall but does not involve lymph nodes

Dukes C

Pathological evidence of adenocarcinoma in one or more lymph nodes

Dukes D

Tumor spread to other organs such as the liver, lung, or bones




  • T: The extent of spread of the primary tumor


  • N: The presence or absence and extent of regional lymph node metastasis


  • M: The presence or absence of distant metastasis

TNM is superior to Dukes because of the greater information it yields, and it is now the preferred system. However, there is controversy because the system is frequently updated. There have been various versions of the TNM staging; thus the version used should be specified (e.g., version 5, version 6, version 7). The most recent seventh edition of the TNM has introduced classification systems for gastrointestinal stromal tumors and neuroendocrine tumors. Currently the United Kingdom and a number of other countries advise using TNM 5 for colorectal cancer, whereas most countries have adopted TNM 7 (Table 23.7) since its introduction in 2009.


Table 23.7
TNM staging of colorectal cancer (7th edition)







Tis: carcinoma in-situ: intraepithelial (within basement membrane) or invasion of lamina propria (intramucosal), with no extension through the muscularis mucosae into the submucosa

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Oct 30, 2017 | Posted by in ABDOMINAL MEDICINE | Comments Off on Principles of Tumor Classification
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