Colorectal cancer diagnostic study of choice
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Colorectal cancer diagnostic study of choice On the Web
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To view the staging of familial adenomatous polyposis (FAP), click here
To view the staging of hereditary nonpolyposis colorectal cancer (HNPCC), click here
Editor-In-Chief: C. Michael Gibson, M.S., M.D.  Associate Editor(s)-in-Chief: ; Roukoz A. Karam, M.D. Saarah T. Alkhairy, M.D.; Elliot B. Tapper, M.D.
Diagnostic Study of Choice
Study of choice
A colonoscopy checks for polyps and other abnormalities in the entire colon and rectum. A colonoscopy has the advantage that if polyps are found during the procedure they can be immediately removed, and the tissue can also be taken for biopsy. The American Society for Gastrointestinal Endoscopy has released quality indicators for screening colonoscopy, which include:
- Documentation of prep quality
- Photo documentation of cecal intubation
- Withdrawal time of 6 minutes or more
- Adenoma detection rate of greater than 25% in males and 15% in females greater than 50 years old.
A biopsy can be performed when a suspected lesion is found on colonoscopy. The biopsy specimen is examined for histologic changes and tissue differentiation. Well-differentiated lesions have a good prognosis compared to poorly and undifferentiated lesions.
Colorectal Cancer Staging
- Staging of colorectal cancer is calculated after the diagnosis has been established in order to assess treatment and prognosis.
- Definitive staging can only be achieved after surgery has been performed and pathology reports have been reviewed.
- The most recent revision (2017) of the tumor, node, metastasis staging system (TNM) proposed by the American Joint Committe on Cancer and the Union for International Cancer Control is widely used.
- This staging system depends on 3 main factors including the size of the tumor (T), the degree of lymph node involvement (N), and the presence or absence of distant metastasis (M).
|T - Primary tumor|
|TX||Primary tumor cannot be assessed|
|T0||No evidence of primary tumor|
|Tis||Carcinoma in situ (intraepithelial or invasion of lamina propria)|
|T1||Tumor invades the submucosa|
|T2||Tumor invades the muscularis propria|
|T3||Tumor invades through the muscularis propria into subserosa or into pericolic/perirectal tissues|
|T4||Tumor directly invades other organs and/or perforates visceral peritoneum|
|T4a||Tumor perforates through the visceral peritoneum|
|T4b||Tumor directly invades other organs|
|N - Regional lymph nodes|
|NX||Regional lymph nodes cannot be assessed|
|N0||No regional lymph node metastasis|
|N1||Metastasis to one to three regional lymph nodes|
|N1a||Metastasis to one regional lymph node|
|N1b||Metastasis to two or three regional lymph nodes|
|N1c||Negative regional lymph nodes, but spread into areas of fat near the lymph nodes|
|N2||Metastasis to four or more regional lymph nodes|
|N2a||Metastasis to four to six regional lymph nodes|
|N2b||Metastasis to seven or more regional lymph nodes|
|M - Distant metastasis|
|MX||Distant metastasis cannot be assessed|
|M0||No distant metastasis|
|M1a||Metastasis to one organ/site without peritoneal metastasis|
|M1b||Metastasis to two or more organs/sites without peritoneal metastasis|
|M1c||Metastasis to the peritoneal surface and/or metastasis to other organs/sites|
|Stage IVA||any T||any M||M1a|
|Stage IVB||any T||any M||M1b|
|Stage IVC||any T||any M||M1c|