Overview Colon cancer is the second most commonly diagnosed cancer. 1/12 people will develop bowel cancer before the age of 85. However, there are Survival rates are increasing. Early bowel cancer is cured by surgery alone (screening is important!!). If untreated, or diagnosed when distance metastases are present, >98% pf patients die in <5 years.
Definition Polyps: protuberance into the lumen of normally flat colonic mucosa Colorectal Cancer: Cancer of the colon and/or rectum usually at an advanced age. It is an adenoma and the primary site of metastasis is the liver. Familial Adenomatous Polyposis: autosomal dominant inheritance (mutation of the adenomatous polyposis coli gene), characterised by hundred to thousands of colorectal adenomas usually by age 20. Lynch Syndrome: autosomal dominant inheritance (mutation of the mismatch repair gene) predisposing one to develop cancer at a younger age. |
The colon is divided into:
The ascending and descending colon are retroperitoneal, these are immobile. The transverse is mobile and lies within the peritoneal cavity. The transverse colon is supported by the greater omentum superiorly and attaches to the posterior abdominal wall (in front of the retroperitoneal cavity) by the transverse mesocolon.
The transverse colon is attached to the greater curvature of the stomach and first part of the duodenum via the greater omentum. The sigmoid colon is also attached
Main features of large intestine structure:
Blood supply - from superior and inferior mesenteric artery
Autonomic nerve supply
Watch The Colon Anatomy and Colon Cancer |
Signs and symptoms vary depending on the location of the tumour. 20% of people present at emergency with obstruction of large bowel or perforation
CLINICAL PRESENTATION | |||
Right Colon | Left and Sigmoid Colon | Rectum | |
Frequency | 20% | 75% | 5% |
Pathology | Exophytic lesions wit occult bleeding | Annular, invasive lesions | Ulcerating |
Symptoms | Weight los, weaknes, rarely obstruction | Constipation, change in bowel habits, abdominal pain, rectal bleeding | Obstruction, tenesumus, rectal bleeding |
Signs | Fe+ deficiency anaemia, QLR mass (10%) | Palpable mass on Digital Rectal Examination |
Remember Elderly persons who present with iron-deficiency anemia should be investigated for colon cancer |
Remember Occult blood in the stool of a person older than 40 years should be considered colon cancer until proven otherwise. To rule out colon cancer, perform a colonoscopy. |
Clinical Examination
Remember Screening for colon cancer is available: FOBT. Done yearly after 50yo (Australia). |
Diagnosis Colon cancer is usually diagnosed with colonoscopy and biopsy (takes 1-2 days for pathology results)
Remember Blumer’s shelf: A firm lump felt in the perirectal pouch on rectal examination. It is a rare physical finding in patients with metastatic adenocarcinoma from the GIT usually the stomach. |
Duke's staging (5 year survival rate)
Management
Complications
Hand-Foot Syndrome is a side effect for 5-fluorouracil chemotherapy characterised by a tender, symmetrical erythema of the palms and sole of foot. |
Prognosis (Based on Dukes) Criteria 5-year survival rates for colorectal cancer are:
Screening
Overview
Other manifestations
Overview
Overview
Video: Colorectal Cancer Overview |