THE REGISTRATION OF COLORECTAL CANCER. The anatomy of the colon rectum and anus,the pathology and treatment of colorectal cancer, and the collection of data on colorectal cancer. FIVE FACTS ABOUT COLORECTAL CANCER. Incidence:
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The anatomy of the colon rectum and anus,the pathology and treatment of colorectal cancer, and the collection of data on colorectal cancer.
1 in 14 men and 1 in 20 women in the TCR area develop colorectal cancer during their lifetime. Incidence rates increase with age.
For people in the TCR area the 5 yr survival estimates are:
42% for colon tumours, 45% for rectal tumours. For anal tumours the figures are 47% for men and 60% for women.
Colon and rectum cancers are most common in developed countries. Anal cancer is most common in patients with HIV and sexually transmitted disease, especially in homosexual men.
Western diet, hereditary factors (e.g. familial polyposis coli), inlammatory diseases (e.g. Chrohn’s)
joining the ileum (at the ileocaecal valve) to the external surface of the
body (at the anus).
It is lined with mucous membrane which:
Absorbs water and salts from the liquid contents of the ileum, to form faeces.
Secretes mucous to facilitate the passage of faeces.
Contains neuroendocrine cells to control the function of the intestine
The muscular tube then expels the faeces at the anus.THE ANATOMY & FUNCTION OF THE COLON, RECTUM & ANUS
The hepatic flexure
The splenic flexure
Cancer registries treat each individual part of the
large intestine as a separate tumour site.
This means that a patient with tumours in:
- the caecum and
- ascending colon
will be registered for 2 malignancies irrespective of tumour type.
A patient with two separate tumours in the ascending colon will be registered for:
- a single malignancy if the tumours both
have the same morphology, and
- 2 separate malignancies if the morphologies
are different.THE REGISTRATION OF MALIGNANCIES OCCURING IN THE LARGE INTESTINE
N.B. Many clinicians regard the colon and rectum as a single organ - the large intestine.This may lead to duplicate cancer registrations when a rectal tumour is loosely referred to as “colon cancer”.
the membrane lining the bowel wall. As
this is glandular tissue the majority of
- Mucin secreting >80%
- Mucinous 15%
- Signet ring cell 2%
Arising from neuroendocrine cells
MALIGNANT LYMPHOMA (<1%)
Tumours may also arise in the muscle
wall of the intestine. They may be
Gastrointestinal stromal tumours (GIST), which may be of uncertain malignancy (borderline), or invasive.
Leiomyosarcoma, a malignant tumour of smooth muscle.TOPOGRAPHY AND MORPHOLOGY OF COLORECTAL CANCER
The subdivisions of the large intestine, showing the percentage of all intestinal tumours that occur at each site
Most colorectal adenocarcinomas are thought to arise in adenomatous polyps, most often villous adenomas. Villous adenomas are registered because of their capacity to turn malignant.
An adenocarcinoma of the colon - L. This is likely to have arisen in a solitary polyp which has since been destroyed by the tumour.
A segment of rectum showing polyposis coli. A carcinoma has developed just above the anal margin.
DUKES STAGE is the most widely accepted and used staging system for
colorectal cancer. It was originally introduced as a pathological grade (i.e. taken
from the surgical specimen).
Stage B may be divided according to whether the tumour has just penetrated
the outer surface of the bowel wall (B1) or the surrounding tissues are involved
(B2), and stage C according to whether the apical nodes are involved (C2) or
The ASTLER-COLLERsystem is based on Dukes but the values:
A, B1, B2, C1, C2, D1, D2have slightly different definitions.
Regional lymph nodes
Dukes C tumour involving regional nodes
Dukes B tumour invading pericolic/
Dukes A tumour confined to bowel wall
MODIFIED DUKES CLASSIFICATION OF COLORECTAL TUMOURS
Dukes B2 tumour penetrating through bowel wall into surrounding tissue
Dukes A tumour confined to bowel wall
Dukes B1 tumour penetrating the full thickness of the bowel wall, but not invading surrounding tissue
Other, more sophisticated staging and grading systems have been
introduced, e.g.JASS, which deals with a number of different
prognostic factors, but DUKES is the most important being the most
widely accepted and used.
stages 0, 1, 2A,2B,3A, 3B, 3C,4
N.B. Cancer registries record how far the patient’s tumour has
spread (i.e. the tumour stage) AT DIAGNOSIS.
Removal of all or part of the organ,
together with regional lymph nodes,
i.e. Colectomy, Hemicolectomy, Sigmoid
colectomy, Anterior resection or
Abdominoperineal resection of rectum
In all of these cases an anastomosis
and/or colostomy (temporary or
permanent) will be required.
For localised disease a local excisionof
the tumour may be sufficient. The
excision may be endoscopic for more
The normal colon is too sensitive to
radiation damage to allow radical
radiotherapy to be given. Smaller doses
of radiation may be given preoperatively
to make an inoperable tumour operable,
or postoperatively to increase survival.
5-Fluorouracil (5FU) is the drug most
commonly given, either to improve
survival after surgery, or palliatively.
5FU is often given in combination with
Folinic acid (FA – Calcium leucovorin)
or Levamisole.TREATMENT FOR COLORECTAL CANCER
- Anal margin tumours are more
common in men
- Anal canal tumours are more common in women
Tumours of the anal margin are
usually well differentiated and akin
to skin tumours.
Tumours of the anal canal are more
likely to be poorly differentiated.
Types of malignancy arising in the
Squamous cell carcinoma (90%)
Cloacogenic carcinoma (basaloid tumour)(anal canal only)
Squamous cell and basal cell
carcinomas may occur in the skin
around the anal margin. They are
classified as skin tumours, not
anal ones.ANAL CANCERMalignanciesarising in the anus have different characteristics from other colorectal tumours
is required for tumours of the anal canal.
External beam or interstitial radiotherapy is used as the first line
treatment if possible, as it preserves the function of the sphincter
Adjuvant chemotherapy may be given, but the side effects are very fierce.