Colorectal cancer

Question 1

In which part of the bowel is it most common for patients to develop cancer?

Answer 1

rectal: 40%
sigmoid: 30%
ascending colon /caecum: 15%
transverse colon: 10%
descending colon: 5%

Question 2

What two genetic mutations can predispose patients to developing colorectal cancer?

Answer 2

HNPCC - hereditary non-polyposis colorectal carcinoma

FAP - familial adenomatous polyposis

Question 3

How is HNPCC inherited

Answer 3

autosomal dominant

Question 4

Where do cancers related to HNPCC usually occur in the bowel?

Answer 4

90% = proximal colon

(usually poorly differentiated and highly aggressive)

Question 5

What gene mutations in HNPCC commonly cause the cancer to develop

Answer 5

MSH2 (60%)
MLH1 (30%)

Question 6

What other cancer are patients with HNPCC at risk of

Answer 6

ENdometrial

Question 7

Describe what happens in Familial Adenomatous Polyposis (FAP)

Answer 7

• formation of hundreds of polyps by the age of 30-40 years. => inevitable progression from polyp to cancer

Question 8

What genetic mutation is responsible for Familial Adenomatous Polyposis?

Answer 8

Mutation in APC tumour suppressor gene

(adenomatous polyposis coli)

located on chromosome 5

Question 9

How are patients with Familial Adenomatous Polyposis treated in order to prevent development of cancer?

Answer 9

Patients generally have a total colectomy with ileo-anal pouch formation in their twenties.

Question 10

Patients with FAP are also at risk of what other tumour type?

Answer 10

Duodenal

Question 11

A variant of FAP is called Gardner’s syndrome. What other tumours can these patients develop?

Answer 11

• osteomas of the skull and mandible
• retinal pigmentation
• thyroid carcinoma
• epidermoid cysts on the skin

Question 12

What groups of patients should be referred urgently (<2 weeks) for suspicion of colorectal cancer?

Answer 12

> 40y - unexplained weight loss AND abdo pain

> 50y - unexplained PR bleeding

> 60y - iron def anaemia/altered bowel habit

OR FIT test +ve

Question 13

What other symptoms may you “consider” an urgent suspicion of cancer referral?

Answer 13

• rectal or abdominal mass
• unexplained anal mass or anal ulceration

< 50 years - PR bleeding AND any of the following:
- abdominal pain
- change in bowel habit
- weight loss
- iron deficiency anaemia

Question 14

How often should a FIT test be completed for the bowel screening programme?

Answer 14

every 2 years

Question 15

What age do patients receive a FIT test?

Answer 15

50 to 74 years in Scotland
60 to 74 years in England

Patients >74 years may request further screening

Question 16

What investigation can be offered to patients with an abnormal FIT test result?

Answer 16

Colonoscopy

Question 17

When can a FIT test be offered if not during routine screening?

Answer 17

Symptomatic patient who does not meet the 2 week wait criteria

> 50y with abdo pain OR weight loss

<60y with new IDA/ altered bowel habit

> 60y with anaemia in absence of iron deficiency