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Malignant Neoplasm of the Colon and Rectum B066

Last amended 
21 March 2024
Current RMA Instruments
Reasonable Hypothesis SOP
19 of 2022
Balance of Probabilities SOP
20 of 2022
Changes from previous Instruments

SOP Bulletin 228

ICD Coding
  • ICD-10-AM Codes: C18, C19, C20

Brief description

This is a primary cancer of the lining of the large intestine (colon or rectum).  Primary means that the cancer arose in the colon or rectum and did not arrive secondarily from another body site.

Confirming the diagnosis

Information on histology (from biopsy, surgery, or autopsy) is required to confirm the diagnosis and apply the SOP.  There are SOP factors specific to MN of the colon only, so information on tumour location will be required to apply those factors.

The relevant medical specialist is a general surgeon, colorectal surgeon or gastroenterologist.

Additional diagnoses covered by these SOPs
  • adenocarcinoma of the colon or rectum
  • adenosquamous carcinoma of the colon or rectum
  • carcinoma of the appendix
  • carcinoma of the colon or rectum
  • medullary carcinoma of the colon or rectum
  • mucinous (colloid) adenocarcinoma of the colon or rectum
  • signet ring carcinoma of colon or rectum
  • small cell (oat cell) carcinoma of the colon or rectum
  • squamous cell (epidermoid) carcinoma of the colon or rectum
  • undifferentiated carcinoma of the colon or rectum
Related conditions that may be covered by SOP (further information required)
  • colon cancer
  • cancer of the colon
  • cancer of the rectum
  • rectal cancer
Conditions excluded from SOP
  • adenoma of the colon or rectum*
  • carcinoid of the colon or rectum#
  • carcinoma-in- situ of the colon or rectum# 
  • Hodgkin’s lymphoma* of the colon or rectum
  • non-Hodgkin lymphoma* of the colon or rectum
  • secondary/metastatic cancer/carcinoma involving the colon or rectum (code to primary site)
  • soft tissue sarcoma* of the colon or rectum

* another SOP applies

# non-SOP condition

Clinical onset

Clinical onset will generally be at the time of diagnosis.  Symptoms are non-specific, but it may be possible to back-date onset on the basis of symptoms such as rectal bleeding, change in bowel habit or loss of weight.

Clinical worsening

The only SOP worsening factor is for inability to obtain appropriate clinical management.  Colorectal cancer has a very variable course and prognosis.  It is particularly amenable to treatment if found early.  A delay in appropriate treatment could result in worsening of the condition.  Establishing whether worsening beyond the normal course of the disease has occurred will generally require expert medical opinion.