Colon cancer staging is an estimate of the amount of penetration of a particular cancer. It is performed for diagnostic and research purposes, and to determine the best method of treatment. The systems for staging colorectal cancers depend on the extent of local invasion, the degree of lymph node involvement and whether there is distant metastasis.
Definitive staging can only be done after surgery and histopathology of colorectal carcinoma. An exception to this principle would be after a colonoscopic polypectomy of a malignant pedunculated polyp with minimal invasion. Preoperative staging of rectal cancers may be done with endoscopic ultrasound. Adjunct staging of metastasis include abdominal ultrasound, MRI, CT, PET scanning, and other imaging studies.
The most common staging system is the TNM (for tumors/nodes/metastases) system, from the American Joint Committee on Cancer.[1] This system assigns a number based on three categories. "T" denotes the degree of invasion of the intestinal wall, "N" the degree of lymphatic node involvement, and "M" the degree of metastasis. Possibly, the overall Joint Committee stage is a shorter format of the TNM stage, and is usually quoted as a number I, II, III, IV derived from the TNM value grouped by prognosis; a higher number indicates a more advanced cancer and likely a worse outcome. Following is the eighth edition from 2017:
Numbers 0 to 4, with subgroups, are used to describe deepest tumor depth:[2]
Numbers 0 to 2, and subgroups, are used to describe lymph node involvement:[2]
Numbers 0 and 1, with subgroups, describe the metastasis status:[2]
AJCC stage[2] | TNM stage[2] | TNM stage criteria[2] |
---|---|---|
Stage 0 | Tis N0 M0 | Tis: Tumor confined to mucosa; cancer-in-situ |
Stage I | T1 N0 M0 | T1: Tumor invades submucosa |
T2 N0 M0 | T2: Tumor invades muscularis propria | |
Stage II-A | T3 N0 M0 | T3: Tumor invades subserosa or beyond (without other organs involved) |
Stage II-B | T4a N0 M0 | T4a: Tumor perforates the visceral peritoneum |
Stage II-C | T4b N0 M0 | T4b: Tumor invades adjacent organs |
Stage III-A |
|
|
Stage III-B |
|
|
Stage III-C |
|
|
Stage IVa | any T, any N, M1a | M1a: Metastasis to 1 other part of the body beyond the colon, rectum or regional lymph nodes. Any T, any N. |
Stage IVb | any T, any N, M1b | M1b: Metastasis to more than 1 other part of the body beyond the colon, rectum or regional lymph nodes. Any T, any N. |
Stage IVc | any T, any N, M1c | M1c: Metastasis to the peritoneal surface. Any T, any N. |
In 1932 the British pathologist Cuthbert Dukes (1890–1977) devised a classification system for colorectal cancer.[3] Several different forms of the Dukes classification were developed.[4][5] However, this system has largely been replaced by the more detailed TNM staging system and is no longer recommended for use in clinical practice.[6]
An adaptation by the Americans Astler and Coller in 1954 further divided stages B and C[8][9]
The stage gives valuable information for the prognosis and management of the particular cancer.[citation needed]
Another modification of the original Dukes classification was made in 1935 by Gabriel, Dukes and Bussey.[10] This subdivided stage C. This staging system was noted to be prognostically relevant to rectal and colonic adenocarcinoma.[11] Stage D was added by Turnbull to denote the presence of liver and other distant metastases[12]