Colorectal cancer

Question 1

What are the strongest risk factors for developing colorectal cancer?

Answer 1

1. Increasing age
2. Hereditary syndromes
3. Increased alcohol intake
4. Smoking
5. Processed meat
6. Obesity
7. Previous exposure to radiation
8. Inflammatory bowel disease

Question 2

What hereditary syndromes contribute to colorectal cancer?

Answer 2

Familial adenomatous polyposis
Lynch Syndrome
Juvenile polyposis
Peutz-Jeghers syndrome

Question 3

What classification system is used for colorectal cancer?

Answer 3

Duke’s classification

Question 4

What are the classifications of Duke’s classification system?

Answer 4

A: limited to the bowel wall (i.e. not beyond the muscularis).
B: extending through the bowel wall (i.e. beyond the muscularis).
C: regional lymph node involvement.
D: distant metastases.
It is important to learn the Duke’s staging for examinations.

Question 5

What are the current screening guidelines for colorectal cancer?

Answer 5

Faecal immunochemical test (FIT) every 2 years for men and women age 60-74.

If positive patients are referred for colonoscopy.

Question 6

How effective is the screening programme for colorectal cancer?

Answer 6

This screening programme reduces the risk of dying from bowel cancer by 16%.

Question 7

What are the criteria for an urgent 2 week referral for colorectal cancer?

Answer 7

Aged > 40 with unexplained weight loss AND abdominal pain

Aged > 50 with unexplained rectal bleeding

Aged > 60 and over with any change in bowel habit OR iron-deficient anaemia

Question 8

What investigation would you do for suspected colorectal cancer?

Answer 8

Colonoscopy

Question 9

How would you manage patients with colon cancer?

Answer 9

For stage I-III disease: surgical resection ± post-operative chemotherapy

For stage IV disease (metastases): pre AND post-operative chemotherapy

Question 10

How would you manage patients with rectal cancer?

Answer 10

For patients with rectal cancer suitable for surgery:

1. Anterior resection for tumours >8 cm from the anal canal or involving the proximal 2/3 of the rectum.
2. Abdomino-perineal (AP) resection for tumours <8 cm from the anal canal or involving the distal 1/3 of the rectum.

Patients with stage III disease benefit from post-operative chemotherapy.

Patients with stage IV disease benefit from post-operative chemoradiotherapy

Question 11

How would you manage patients with colorectal cancer who are not suitable for surgery?

Answer 11

For patients unsuitable for surgery management is with chemotherapy

New monoclonal antibody therapies are becoming available

If the patient presents with acute bowel obstruction, a Hartmann’s procedure may be required as an interim measure (resection of the rectosigmoid colon with formation of a temporary end colostomy and anorectal stump).

Question 12

What are the key features of familial adenomatous polyposis?

Answer 12

Caused by a mutation in the adenomatous polyposis coli (APC) gene and has an autosomal dominant inheritance pattern.

Patients develop hundreds of adenomatous polyps in their teens and are virtually guaranteed to develop colorectal cancer by their 20s, unless they undergo prophylactic proctocolectomy.

Question 13

How would you manage patients with familial adenomatous polyposis?

Answer 13

Regular endoscopies

Question 14

What is Gardener’s syndrome?

Answer 14

Gardener’s syndrome is a variant of FAP in which patients may also develop epidermal cysts, supernumerary teeth, osteomas, and thyroid tumours.

Question 15

What are the key features of Lynch syndrome?

Answer 15

Is caused by a mutation in the mismatch repair genes MLH1/MSH2 and has an autosomal dominant inheritance pattern.

Patients have an 80% risk of developing colorectal cancer by their 30s.

There is increased risk of additional cancers such as gastric, endometrial, breast, and prostate cancer.

Question 16

How would you manage patients with Lynch syndrome?

Answer 16

Regular endoscopies

Question 17

What are the key features of Peutz-Jehgers syndrome?

Answer 17

Is caused by a mutation in the STK11 gene and has an autosomal dominant inheritance pattern.

Patients typically present in their teens with mucocutaneous pigmentaiton and hamartomatous polyps.

Note that the risk of neoplastic transformation of hamartomatous polyps is low, but many polyps are present so patients are at increased risk of developing colorectal cancer.

Question 18

What are the Amsterdam criteria for Lynch syndrome?

Answer 18

Requires the presence of at least three family members with colorectal cancer, extending over at least two generations, with at least one person diagnosed before the age of 50 years, and one affected person a first‐degree relative of the other two.