Lecture 13: Bowel Cancer

Question 1

geographically, where is bowel cancer most prevalent

Answer 1

western world

Question 2

risk factors for bowel cancer

Answer 2

• individuals migrating from low risk to high risk area
• foods rich in red meat and fat
• longstanding ulcerative colitis
• crohn’s disease to a lesser extent than UC
• presence of adenoma in large bowel
• history of bowel cancer surgery
• family history of bowel cancer
• old age

Question 3

what is a polyp

Answer 3

• a protruding growth into a hollow viscus

- can be benign, adenoma or malignant

Question 4

what is an adenoma

Answer 4

precancerous lesions that consist of dysplastic epithelium

Question 5

types of polyp and what they look like

Answer 5

hyperplastic
- numerous goblet cells giving lace like appearance
tubular
- test tube like appearance
villous
- finger like appearance
tubular
tubulovillous
- features of both tubular and villous

Question 6

how many polyps does a patient need for a diagnosis of familial adenomatous polyposis

Answer 6

at least 100, but most patients have 500 - 2500

Question 7

where is the defective gene for familial adenomatous polyposis

Answer 7

chromosome 5q21, also known as the APC gene

Question 8

genetic abnormalities associated with bowel cancer

Answer 8

• lynch syndrome
• familial adenomatous polyposis
• attenuated FAP
• familial colorectal cancer type x
• MUTYH associated polyposis
• serrated polyposis syndrome
• hamartomatous polyposis syndrome

Question 9

what are microsatellites

Answer 9

tandem repeats of nucleotides

Question 10

which genes are involved in Lynch Syndrome

Answer 10

• MSH2 and MLH1 account for 30%

- PMS1 and PMS2 are others

Question 11

what are the factors of the amsterdam criteria

Answer 11

• 3 or more relatives with LS associated cancer
• one affected patient should be first degree relative of the other two
• two or more successive generations affected
• cancer in one or more diagnosed before 50
• tumours should be verified by pathological examination

Question 12

symptoms of bowel cancer

Answer 12

• can be asymptomatic and detected during screening
• change in bowel habits, eg alternating between constipation and diarrhoea
• bleeding from rectum
• anaemia
• abdominal pain