Colorectal Cancer

Question 1

What are the risk factors for colorectal cancer? (8)

Answer 1

Age
Male
Previous adenoma

Environmental factors:
Diet
Obesity 
Lack of exercise 
Diabetes mellitus
Smoking

Question 2

What are the two main histological subtypes of colorectal polyps?

Answer 2

Tubular
Vilous
(Indeterminate tubulovilous)

Question 3

What are the three main steps in the adenoma-carcinoma development?

Answer 3

Activation of oncogene (kras, c-myc)
Loss of tumour suppression gene (APC, p53, DCC)
Defective DNA repair pathway genes

Question 4

What are the main presentations of colorectal cancer? (6)

Answer 4

Rectal bleeding
Altered bowel opening (diarrhoea)

Iron deficiency anaemia
Palpable rectal or right lower abdominal mass
Acute colonic obstruction if stenosing tumor
Systemic symptoms e.g. anorexia, weight loss

Question 5

What is the mainstay investigation of colorectal cancer?

Answer 5

Colonoscopy

Question 6

What are the potential risks of colonoscopy? (3)

Answer 6

Bowel perforation, bleeding
Risks of sedation
Bowel preparation (risk for patients with renal problems)

Question 7

What radiological techniques may be used in colorectal cancer other than colonoscopy? (3)

Answer 7

Barium enema
CT colonoscopy
CT abdomen/pelvis

Question 8

What are the disadvantages of using CT colonography? (4)

Answer 8

No histology
No therapeutic intervention
Ionising radiation
Risks of bowel preparation

Question 9

What investigations can be used to stage colorectal cancers?

Answer 9

CT scan for chest/abdomen/pelvis
MRI for rectal tumours
PET scan/rectal endoscopic ultrasound in some cases

Question 10

What are the classifications of Duke’s criteria?

Answer 10

A: tumour confined to mucosa
B: tumour extended to muscle layer
C: involvement of lymph nodes
D: distant metastatic spread

Question 11

What is the main therapy in colorectal cancer?

Answer 11

Surgery in 80% of patients

Question 12

What may be a consequence of surgery for CRC?

Answer 12

Stoma formation

Question 13

Which types of colorectal cancer may receive chemotherapy? (3)

Answer 13

Duke C
Duke B if advanced
Palliative cases

Question 14

What are the main forms of prevention for colorectal cancer? (2)

Answer 14

Adjusting lifestyle factors

Screening

Question 15

What does FOBT stand for?

Answer 15

Faecal occult blood test

Question 16

What are some of the modalities of screening for colorectal cancer?

Answer 16

FOBT

Question 17

What age are patients in Scotland called for FOBT?

Answer 17

Between 50-74 years old

Question 18

How often are patients in Scotland called for FOBT?

Answer 18

Every 2 years

Question 19

What is the next stage if FOBT is positive?

Answer 19

Colonoscopy

Question 20

What 2 main heritable conditions increase the risk of colorectal cancer?

Answer 20

FAP (familial adenomatous polyposis)

HNPCC (hereditary non-polyposis colorectal cancer)

Question 21

How early does screening start in FAP?

Answer 21

Between 10-12 years old

Question 22

What age are patients called for screening in HNPCC?

Answer 22

From 25 years old normally

Question 23

What are the high risk groups for CRC? (6)

Answer 23

HNPCC
FAP
Family history of CRC
IBD
Previous CRC
Previous adenomas

Question 24

What dietary factors may increase risk of CRC? (5)

Answer 24

Increased red meat 
Increased alcohol 
Low fibre
Low calicium
Low fruit and veg intake

Question 25

What are the two main morphological types of colorectal polyps?

Answer 25

Pedunculated

Sessile

Question 26

When do you investigate for CRC in cases of iron deficiency anaemia?

Answer 26

Men of any age

Non-menstruating women

Question 27

What surgery is normally involved in Duke’s A and cancerous polyps?

Answer 27

Endoscopic or local resection

Question 28

When will radiotherapy be used in CRC?

Answer 28

Only in rectal cancer

Question 29

What are the modalities of CRC screening? (5)

Answer 29

FOBT
Faecal immunochemical test 
Flexible sigmoidoscopy 
Colonoscopy 
CT colonography