Colorectal Cancer and Screening

Question 1

What are the risk factors for colorectal cancer?

Answer 1

Sporadic - 85%
Familial risk - 10%
Inheritable conditions - HNPCC
Underlying IBD - 1%

Question 2

What are the risk factors for sporadic cases of colorectal cancer?

Answer 2

Age
Male
Previous adenoma/CRC
Environment - Diet, Obseity & Smoking

Question 3

Where do a majority of CRCs arise from?

Answer 3

Pre-existing polyps

Question 4

What is the origin of adenomas?

Answer 4

Epithelial

Question 5

What are the two main histological types of adenomas?

Answer 5

Tubular
Villous
Intermediate one is tubulovillous

Question 6

What are the presentations of colorectal cancer? (6)

Answer 6

Rectal bleeding
Altered bowel opening
Iron Deficiency Anaemia
Palpable mass
Acute colonic obstruction if stenosing tumour
Systemic symptoms of malignancy

Question 7

What are the investigation for CRC?

Answer 7

Colonoscopy + biopsy

Radiological imaging

Question 8

What are the four classifications of Duke’s Criteria?

Answer 8

A - Confined to mucosa
B - Extended through mucosa to the muscle layer
C - Lymph nodes
D - Metastatases

Question 9

What are the treatment options for CRC?

Answer 9

Surgery
Colostomy
Radiotherapy
Chemotherapy
Lymph node removal
Partial hepactectomy for metastases

Question 10

What are the different types of screening modalities for the general population?

Answer 10

FOBT
FIT
Flexible Sigmoidoscopy
Colonoscopy
CT Colonography

Question 11

What high risk groups should be especially screened?

Answer 11

Heritable conditions - FAP/HNPCC
Inflammatory bowel
Familial risk
Previous adenomas/CRC

Question 12

What is FAP and what type of condition is it?

Answer 12

Familial Adenomatous Polyposis

Autosomal dominant

Question 13

How does FAP present and what happens in early adulthood?

Answer 13

Multiple (>100) adenomas throughout the colon

High risk of malignant change

Question 14

What are the extracolonic manifestations of FAP?

Answer 14

Benign gastric fundic cystic hyperplastic

Duodenal adenomas

Question 15

What is CHRPE?

Answer 15

Congenital Retinal Hypertrophy of the Pigment Epithelia

Question 16

What benefits do NSAIDs have in chemoprevention?

Answer 16

Reduces polyp number

Prevents recurrence of higher-grade adenomas in the retained rectal segment

Question 17

What is HNPCC?

Answer 17

Hereditary Non-Polyposis Colorectal Cancer

Question 18

What has happenned in HNPCC and what type of condition is it?

Answer 18

Mutation in DNA mismatch repair

Autosomal dominant condition

Question 19

What do tumours typically have?

Answer 19

A molecular characteristic called microsatellite instability (MSI) - frequent mutations in short repeated DNA sequences (microsatellites)