Colon Cancer Staging - Stage 3 Colon Cancer

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 has been performed and pathology reports reviewed. 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.

TNM staging system

The most common staging system is the TNM (for tumors/nodes/metastases) system, from the American Joint Committee on Cancer (AJCC). The TNM 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. The broader stage of a cancer 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. Details of this system are in the graph below:

Dukes classification

In 1932 the British pathologist Cuthbert Dukes (1890-1977) and graduate of the University of Edinburgh Medical School devised a famous classification system for colorectal cancer. Several different forms of the Dukes classification were developed. However, this system has largely been replaced by the more detailed TNM staging system and is no longer recommended for use in clinical practice.

• Dukes' A: Invasion into but not through the bowel wall
• Dukes' B: Invasion through the bowel wall penetrating the muscle layer but not involving lymph nodes
• Dukes' C: Involvement of lymph nodes
• Dukes' D: Widespread metastases

Astler-Coller classification

An adaptation by the Americans Astler and Coller in 1954 further divided stages B and C

• Stage A: Limited to mucosa
• Stage B1: Extending into muscularis propria but not penetrating through it; nodes not involved
• Stage B2: Penetrating through muscularis propria; nodes not involved
• Stage C1: Extending into muscularis propria but not penetrating through it. Nodes involved
• Stage C2: Penetrating through muscularis propria. Nodes involved
• Stage D: Distant metastatic spread

The stage gives valuable information for the prognosis and management of the particular cancer.

Full Dukes' classification

Another modification of the original Dukes classification was made in 1935 by Gabriel, Dukes and Bussey. This subdivided stage C. This staging system was noted to be prognostically relevant to rectal and colonic adenocarcinoma. Stage D was added by Turnbull to denote the presence of liver and other distant metastases

• Stage A: Limited to muscularis propria; nodes not involved
• Stage B: Extending beyond muscularis propria; nodes not involved
• Stage C: Nodes involved but highest (apical) node spared
• Stage D: Distant metastatic spread

References