Colon cancer Flashcards
Where does colon cancer most commonly affect?
2/3rd is colonic
1/3rd is rectal
Where is most commonly affected by colon cancer?
- rectal — 40%
- sigmoid — 30%
What are the possible risk factors for colon cancer?
- age (>60 years)
- alcohol, smoking
- low-fibre diet, red meat
- IBD
- neoplastic polyps
- genetic predisposition
What are the main genetic causes of colon cancer?
- Sporadic ⇒ 95%
- HNPCC ⇒ 5%
- FAP ⇒ 1%
What is HNPCC the most common cause of?
Inherited colon cancer
What is another term for HNPCC?
Lynch syndrome
What type of inheritance does lynch syndrome have?
Autosomal dominant condition
Where does HNPCC most commoly affect?
Proximal colon
What are the main mismatch repair genes that cause HNPCC?
MSH2 (60% of cases)
MLH1 (30% of cases)
What other cancers are associated with HNPCC?
Endometrial cancer
Prostate cancer
What does FAP stand for?
- Familial adenomatous polyposis
What type of inheritance does FAP have?
A rare autosomal dominant condition
What does FAP cause?
The formation of hundreds of polyps by the age of 30-40 years
What are the main symptoms of colon cancer?
Abdominal pain
Rectal bleeding
Change in bowel habit
Weight loss
Iron-deficiency anaemia
What can be used to stage colon cancer?
Duke’s classification
What is Dukes A?
Limited to the bowel wall (i.e. not beyond the muscularis).
What is Dukes B?
Extends through the bowel wall (i.e. beyond the muscularis).
What is Dukes C?
Regional lymph node involvement
What is Dukes D?
Distant metastases
What is the current NHS screening for colon cancer?
Faecal immunochemical test (FIT) every 2 years for men and women age 60-74
If a FIT test is positive, what is the next investigation?
Sigmoidoscopy
What is the first investigation for colon cancer?
Colonoscopy
What is the function of a FIT test?
Used to detect, and can quantify, the amount of human blood in a single stool sample
What is the fuction of a colonscopy?
Direct visualization of the colon
Biopsies to be taken
Removal of any polyps seen
What can be done as an alternative to a colonscopy if it cannot be tolerated?
CT colonoscopy
What can be used to stage colon cancer?
CT chest, abdomen and pelvis
What is the function of CEA?
To monitor the theraputic response to intervention
What staging can be used for colon cancer?
TNM staging
What is the management of stage 1-3 disease?
Surgical resection ± post-operative chemotherapy.
What is right hemicolectomy surgery for?
Tumours of the caecum and ascending colon
What is left hemicolectomy surgery for?
Distal transverse colon and descending colon
What is sigmoid colectomy surgery for?
Tumours of the sigmoid colon.
What is the surgical management of tumours >8 cm from the anal canal or involving the proximal 2/3 of the rectum?
Anterior resection
What is the surgical management of recal tumours <8 cm from the anal canal or involving the distal 1/3 of the rectum.
Abdomino-perineal (AP) resection
What symptoms in someone over 40 would require an urgent 2 week wait referal?
Unexplained weight loss AND abdominal pain
What symptoms in someone over 50 would require an urgent 2 week wait referal?
Unexplained rectal bleeding
What symptoms in someone over 60 would require an urgent 2 week wait referal?
Iron–deficiency anaemia
Changes in their bowel habit
