Staging of colorectal cancer using TNM classification

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:
• 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:

1. NICE. Colorectal cancer (management in people aged 18 and over). NG151. 2020, updated December 2021