Colorectal cancer

Development of post-surgical staging

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Development of post-surgical staging[edit source]

The first well-documented and tested staging system was that of Dukes.[1] This classification system was based entirely on the extent of direct tumour spread through the bowel wall and the presence or absence of lymph node metastases in the resected specimen. Although Dukes staging was originally conceived for rectal cancer, it is also applicable to colon cancer. Dukes stages A, B and C correlate well with patient survival, and are easy to recall and apply. For these reasons the system is widely adopted and remains an objective, unambiguous classification adaptable to multidisciplinary patient care. However, the Dukes system does not address the important issue of ‘residual tumour’ identified by the surgeon at the time of bowel resection, either local due to tumour transection or due to known distant metastases.

The Dukes (A, B, C) system was further modified by Turnbull, who added a stage ‘D’ for cases with known distant metastases and locally unresectable tumour.[2] Thus, Turnbull introduced the concept of clinicopathological staging in which residual tumour, found by the surgeon at the time of bowel resection, could determine the assigned stage. Clinicopathological staging has now gained wide acceptance as the preferred method of staging.

The ACPS system was recommended for use in Australia following two workshops on staging held in Brisbane in 1981.[3] The system was validated using prospectively collected data from the Concord Hospital Colorectal Cancer Project. The ACPS is essentially a simplified version of the system used at Concord Hospital since 1971.[4][5] The ACPS and Concord systems are shown in Table 8.1.

Table 8.1. ACPS/Concord substaging definitions[edit source]

ACPS Concord substage Maximum spread
A0 A1 Mucosa
A A2 Submucosa
A3 Muscularis propria
B B1 Beyond muscularis propria
B2 Free serosal surface involvement by direct spread
C C1 Local nodes involved
C2 Apical nodes involved
D D1 Tumour transected (histological)
D2 Distant metastases (clinical or histological)

Source: Davis and Newland 1983[3]
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A TNM system acceptable to both the Union Internationale Contre Le Cancer (UICC) and the American Joint Committee for Cancer (AJCC)[6] was agreed in 1986 with the aim of attempting to achieve uniformity in staging of Colorectal Cancer (Tables 8.2 and 8.3)[7][8]. The ‘p’ prefix is used to indicate postsurgical pathological staging. This system is now in its 8th edition (implementation date 1/1/2018) and has undergone several significant revisions to the numerical coding with successive editions, including interpretation of mesenteric lymph node and non-lymph node associated tumour deposits.[9] Between the 6th and 7th editions of the AJCC cancer staging manual, the definitions of T4a and T4b were reversed, a code was added to indicate the presence of extramural tumour deposits in the absence of lymph node metastasis (N1c), and the MX code was deleted. In the 8th edition, the definitions of carcinoma in situ and lymph node status have been further refined. A separate M code has been introduced for peritoneal carcinomatosis, which has been separated out from M1b into M1c. The prognostic and predictive implications of microsatellite instability (MSI), mutations of KRAS, NRAS and BRAF are also discussed.

Table 8.2. Pathological TNM staging nomenclature[edit source]

T — primary tumour
TX Primary tumour cannot be assessed
T0 No evidence of primary tumour
Tis Carcinoma in situ: intramucosal (involvement of lamina propria with no extension through muscularis mucosae)
T1 Tumour invades submucosa (through muscularis mucosae but not into the muscularis propria)
T2 Tumour invades muscularis propria
T3 Tumour invades through muscularis propria into pericolorectalic (subserosal) tissues
T4 Tumour invades the visceral peritoneum or invades or adheres to adjacent organ or structure
T4a Tumour penetrates to the surface of the visceral peritoneum (including gross perforation of the bowel through areas of inflammation to the surface of the visceral peritoneum)
T4b Tumour directly invades or adheres to other organs or structures
N - regional lymph node
NX Regional lymph nodes cannot be assessed
NO No regional lymph nodes metastases
N1 One to three regional nodes are positive (tumour in lymph nodes measuring >0.2mm), or any number of tumour deposits are present and all identifiable lymph nodes are negative
N1a One regional lymph node is positive
N1b Two or three regional lymph nodes are positive
N1c No regional lymph nodes are positive, but there are tumour deposits in the
  • subserosa
  • mesentery
  • or non-peritonised pericolic or perirectal/mesorectal tissues
N2 Four or more regional lymph nodes are positive
N2a Four to six regional lymph nodes are positive
N2b Seven or more regional lymph nodes are positive
M — distant metastasis
MO No distant metastasis by imaging, etc; no evidence of tumour in distant sites or organs (This category is not assigned by pathologists.)
M1 Metastasis to one or more distant sites or organs or peritoneal metastasis is identified
M1a Metastasis to one site or organ is identified without peritoneal metastasis
M1b Metastases to two or more sites or organs is identified without peritoneal metastasis
M1c Metastasis to the peritoneal surface is identified alone or with other site or organ metastases

Source: AJCC 2017[9]
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Table 8.3. AJCC prognostic stage groups[edit source]

Stage T N M
0 Tis N0 M0
I T1

T2

N0

N0

M0

M0

IIA T3 N0 M0
IIB T4a N0 M0
IIC T4b N0 M0
IIIA T1-T2

T1

N1/N1c

N2a

M0

M0

IIIB T3-T4a

T2-T3
T1-T2

N1/N1c

N2a
N2b

M0

M0
M0

IIIC T4a

T3-T4a
T4b

N2a

N2b
N1-N2

M0

M0
M0

IVA Any T Any N M1a
IVB Any T Any N M1b
IVC Any T Any N M1c

Source: AJCC 2017[9]

Next section: post-surgical staging following neoadjuvant therapy

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References[edit source]

  1. Dukes, CE. The classification of cancer of the rectum. J. Pathol. 1932 [cited 2012 Dec 16];35(3); 323-332 Available from: http://onlinelibrary.wiley.com/doi/10.1002/path.1700350303/abstract.
  2. Turnbull RB Jr, Kyle K, Watson FR, Spratt J. Cancer of the colon: the influence of the no-touch isolation technic on survival rates. Ann Surg 1967 Sep;166(3):420-7 Available from: http://www.ncbi.nlm.nih.gov/pubmed/6039601.
  3. 3.0 3.1 Davis NC, Newland RC. The reporting of colorectal cancer: The Australian clinico-pathological staging system. Aust N Z J Surg 1982 Aug;52(4):395-7 Available from: http://www.ncbi.nlm.nih.gov/pubmed/6180723.
  4. Newland RC, Chapuis PH, Pheils MT, MacPherson JG. The relationship of survival to staging and grading of colorectal carcinoma: a prospective study of 503 cases. Cancer 1981 Mar 15;47(6):1424-9 Available from: http://www.ncbi.nlm.nih.gov/pubmed/7226068.
  5. Newland RC, Chapuis PH, Smyth EJ. The prognostic value of substaging colorectal carcinoma. A prospective study of 1117 cases with standardized pathology. Cancer 1987 Aug 15;60(4):852-7 Available from: http://www.ncbi.nlm.nih.gov/pubmed/3594403.
  6. Davis NC, Newland RC. Terminology and classification of colorectal adenocarcinoma: the Australian clinico-pathological staging system. Aust N Z J Surg 1983 Jun;53(3):211-21 Available from: http://www.ncbi.nlm.nih.gov/pubmed/6309132.
  7. Hermanek, P.. The TNM/p TNM classification of colorectal carcinomas — what has changed and why? 1986 [cited 2016 Dec 16];10, p 6-12.
  8. Beahrs OH, American Cancer S, American Joint Committee on C. Manual for staging of cancer. Philadelphia, USA: Lippincott; 1992 [cited 2016 Dec 16].
  9. 9.0 9.1 9.2 Amin MB, Edge S, Greene F, Byrd DR, Brookland RK, Washington MK, Gershenwald JE, Compton CC, Hess KR, et al. (Eds.). AJCC Cancer Staging Manual (8th edition). Springer International Publishing: American Joint Commission on Cancer; 2017 [cited 2016 Dec 28].

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