Stage
T
N
M
0
Tis
N 0
M 0
1
T 1–2
N 0
M 0
2 A
T 3
N 0
M 0
2 B
T 4 a
N 0
M 0
2 C
T 4 b
N 0
M 0
3 A
T 1–2
N 1
M 0
3 B
T 3–4
N1
M 0
T 1–3
N2a
M 0
T 1–2
N 2b
M 0
3 C
Any T
N2
M 0
T 4b
N1a-b
M 0
4
Any T
Any N
M 1
Based on a combination of T, N, and M for any given tumor, an overall stage from stage I to IV can be determined. The most recent AJCC/UICC definitions were published in 2010.
The T stage can be divided into categories based on the depth of invasion. Tis, carcinoma in situ, represents a nonmalignant tumor; T1 has invasion into the submucosa, T2 has invasion into the muscularis propria, T3 has invasion into the subserosa or nonperitonealized pericolic or rectal tissue (through the bowel wall), T4a has penetration to the surface of the visceral peritoneum, and T4b has invasion of other organs or structures.
The N stage can also be divided into categories: N0, with no lymph node involvement; N1, with one to three lymph nodes involved (N1a, one node involved; N1b with two to three involved nodes; N1c with tumor deposits in the subserosa mesentery or pericolic tissues); and N2, with four or more lymph nodes involved.
The M stage is divided into two main categories, either no metastases (M0) or distant metastases (M1). M1 is further divided into M1a and M1b (M1a, metastases confined to one organ or site; M1b, metastases in more than one organ/site).
The combination of T, N, and M will lead to one of the four stages based on the combination of findings.
Clinical Prognostic Factors
Age
As with many cancers, colon cancer incidence increases with increasing age. Most series report a mean age in the sixth decade for nonhereditary colon cancer.
Patients with familial adenomatous polyposis (FAP) will present with colon cancer in their mid to late 30s if colectomy is not performed prior to this age.
Patients with Lynch syndrome (HNPCC) can present at any age, but tend to have colon cancer between the ages of 40 and 50.
Younger patients present with worse tumors of more advanced stage and grade. However, stage for stage they have an equivalent or improved 5-year survival.
Presentation
Obstruction and perforation are poor prognostic signs often associated with advanced disease. In addition, because patients are operated on in an urgent fashion, their operative morbidity and mortality is increased.
Perforated cancers had a 9 % operative mortality compared to obstructed cancers of 5 %. Overall 5-year survival was 33 % in each group, much lower than the expected rate based on similar stages in noncomplicated cases.
Blood Transfusion
Blood transfusions can cause immunosuppression in the postoperative period, which may allow for an inability to combat tumor cells shed at the time of surgery and theoretically lead to a worse prognosis.
Chung et al. reviewed 20 papers, representing 5,236 patients supporting the hypothesis that perioperative blood transfusions are associated with an increased recurrence and death from colon carcinoma.
Adjacent Organ Involvement
Local extension of colon carcinoma (occurs in 5–12 %) can involve any structure or organ adjacent to the primary tumor (T4b).
For right colon cancers the most commonly involved structures are the liver, duodenum, pancreas, and abdominal wall. Extended resections (en bloc) provide equivalent survival compared to similar T3 tumor.
Histologic/Biochemical/Genetic Factors
Histologic Grade
Broders classified adenocarcinomas by the degree of differentiation. He originally described four grades.
Today, three grades are used and include Grade 1 with well-differentiated features, Grade 2 moderately differentiated, and Grade 3 poorly differentiated.
The vast majority of colon cancers are moderately differentiated (Grade 2) with preservation of gland-forming architecture.Related posts:
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