CRC is usually polypoid mass with ulceration, spreads by direct infiltration through bowel wall, and involves lymphatic and blood vessels with subsequent spread, commonly to the liver and lung. Rectosigmoid tumors may spread to lungs early because of systemic paravertebral venous drainage of this area. Histology is nearly always adenocarcinoma; 75% located distal to the splenic flexure. May be polypoid, sessile, fungating, or constricting {1-3}.

Degree of invasiveness at surgery (Dukes classification) is single best predictor of prognosis (Table 1). Other predictors of poor prognosis are preoperative serum CEA >5 mg/ml (>5 µg/l), poorly differentiated histology, bowel perforation, venous invasion, adherence to adjacent organs, aneuploidy, specific deletion in chromosome 5, 17, 18, and mutation of ras proto-oncogene. 15% have defects in DNA repair {1-3}.

Table 1. Staging and survival of colorectal cancers {1}

ICD-10: the ICD-10 (2010 version) codes for CRC are C18-21. Specifically,

C18 Malignant neoplasm of colon;

C19 Malignant neoplasm of rectosigmoid junction;

C20 Malignant neoplasm of rectum;

C21 Malignant neoplasm of anus and anal canal.

The above codes are those adopted by the World Health Organization International Agency for Research in Cancer (IARC) (http://globocan.iarc.fr/), which includes code C21 anal cancer. Codes included may differ, depending on guidelines that apply.

EU Guideline 2010 {2}

“Due to the improved diagnostic reproducibility of the revised Vienna classification, use of this classification in a format modified for lesions detected in screening is recommended to ensure consistent international communication and comparison of histopathology of biopsies and resection specimens (IV – B). Only two grades of colorectal neoplasia (low grade and high grade) should be used, to minimise intraobserver and interobserver error (V - B). The terms

intra-mucosal adenocarcinoma or in-situ carcinoma should not be used (VI - B).

The WHO definition of colorectal adenocarcinoma should be used: “an invasion of neoplastic cells through the muscularis mucosae into the submucosa” (VI - A).

Adenocarcinomas should be reported according to the TNM classification. The version of TNM

to be used should be decided nationally and should be stated e.g. pT1 pN0 pMX (Version 5) or

pT4 pN2 pM1 (Version 7). These can be further abbreviated to pT1N0MX (v5) or to pT4N2M1

(v7) (VI - B).

The WHO classification of adenomas into tubular, tubulo-villous and villous should be used

(VI - A).

Due to the increased risk of colorectal cancer associated with flat and/or depressed lesions they should be reported as non-polypoid lesions (III), and further classified by the Paris classification

(V - B).

Sub-staging of T1 cancers should be performed to determine the risk of residual disease. Consideration should be given to the appropriate method, which may vary depending on the morphology of the lesion (Kikuchi/Haggitt or measurement). For non-polypoid lesions the Kikuchi stage and for pedunculated lesions Haggitt are currently recommended (VI - C). High-risk features for residual disease such as lack of margin clearance (≤1 mm), poor differentiation and lymphatic and vascular invasion should be reported (V - B). The multidisciplinary team should be consulted on whether or not surgical resection of pT1 adenocarcinoma is recommended; if surgical resection is recommended, consideration should be given to obtaining an opinion from a second histopathologist as variation exists in evaluating high-risk features (VI - A).”

Adaptation of the revised Vienna classification¹ for colorectal cancer screening {2}   1. NO NEOPLASIA:² Vienna Category 1 (Negative for neoplasia)   2. MUCOSAL LOW GRADE NEOPLASIA: Vienna Category 3 (Mucosal low-grade neoplasia, Low-grade adenoma, Low-grade dysplasia); Other common terminology mild and moderate dysplasia; WHO: low-grade intra-epithelial neoplasia   3. MUCOSAL HIGH GRADE NEOPLASIA: Vienna: Category 4.1–4.4 (Mucosal high grade neoplasia, High-grade adenoma/dysplasia, Non-invasive carcinoma (carcinoma in situ), Suspicious for invasive carcinoma, Intramucosal carcinoma); Other common terminology severe dysplasia; high-grade intraepithelial neoplasia; WHO: high-grade intraepithelial neoplasia TNM: pTis   4. CARCINOMA invading the submucosa or beyond: 4a. Carcinoma confined to submucosa Vienna: Category 5 (Submucosal invasion by carcinoma); TNM: pT1 4b. Carcinoma beyond submucosa TNM: pT2-T4   ¹ For revised Vienna classification see Dixon (2002), for WHO classification see WHO (2000), for TNM see (TNM classification of malignant tumours, 5th edition 1997; TNM Classification of malignant tumours, 6th edition 2002; TNM Classification of Malignant Tumours, 7th edition 2009). ² Category 2 of the Vienna Classification (indefinite) is not recommended for screening.