staging of colorectal cancer using TNM classification

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staging of colorectal cancer

Staging of newly diagnosed colorectal cancer includes the assessment of local spread and detection of the presence or absence of distant metastases (1). Offer

  • contrast-enhanced CT of the chest, abdomen and pelvis; should be offered to all patients who are diagnosed with colorectal cancer to estimate the stage of the disease
  • MRI to assess the risk of local recurrence to all  patients with rectal cancer unless it is contraindicated
  • endorectal ultrasound to patients with rectal cancer if MRI shows disease amenable to local excision or if MRI is contraindicated

Several staging systems for colorectal cancer have been described.

  • TNM Staging System developed by the American Joint Commission on Cancer (AJCC) is the most widely used method (2):
    • T - primary tumour.
      • T0: no evidence of primary tumour
      • Tis carcinoma in situ: intraepithelial or invasion of the lamina propria
      • T1 the tumour is confined to the submucosa
      • T2 the tumour has grown into (but not through) the muscularis propria
      • T3 the tumour has grown into (but not through) the serosa
      • T4 the tumour directly invades other organs or structures, and/or perforates visceral peritoneum

    • N - regional lymph nodes
      • N0: no regional nodes involved.
      • N1: 1-3 regional nodes involved.
      • N2: 4 or more regional nodes involved

    • M - distant Metastasis
      • M0: no distant metastasis.
      • M1: distant metastasis present (may be transcoelomic spread)

    • stage grouping
      • stage 0 - Tis N0 M0 (carcinoma in situ)
      • stage 1 - T1 N0 M0, T2 N0 M0
      • stage 2 - T3 T4 N0 M0
      • stage 3 - Any T1-2, N1, M0, any T3-4, N1 M0, any T N2 M0
      • stage 4 - any T, any N, M1

  • Dukes’ staging equivalence to TNM classification-
    • Dukes’ stage A = T1N0M0 or T2N0M0
    • Dukes’ stage B = T3N0M0 or T4N0M0
    • Dukes’ stage C = any T, N1, M0 or any T, N2, M0
    • Dukes’ stage D = any T, any N, M1

Note:

  • findings of digital rectal examinations should not be used as part of the staging assessment

Reference:

Last reviewed 01/2018

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