Colorectal Cancer

Question 1

What are the differentials for fresh blood in the stool?

Answer 1

• Haemorrhoids
• Acute anal fissure (following trauma or severe constipation)
• Colo-rectal neoplasms
• Acute proctitis
• IBD

Question 2

How do you differentiate between haemorrhoids and anal fissures?

Answer 2

Anal fissures present with severe pain on defecation

Haemorrhoids do not have pain but bright red blood is separate from the stool

Question 3

What is an anal fissure?

Answer 3

Break/tear in the skin of the anal canal caused by over-stretching of the anal mucosa

Question 4

Where do colorectal malignancies most commonly occur?

Answer 4

2/3 within colon
- Mostly in the left half (recto-sigmoid colon)
- Second most common = caecum
1/3 within rectum

Question 5

What are the clinical features of colorectal cancer?

Answer 5

• Sudden change in bowel habit
• Unexplained microcytic anaemia (iron deficiency)
• Abdominal/rectal mass
• Intestinal obstruction
• Abdominal pain
• Tenesmus

Question 6

What are the red flags of colorectal cancer?

Answer 6

• Family Hx
• Change in bowel habit >60yrs
• Anaemia
• Unexplained weight loss
• Rectal bleeding
• Rectal or abdominal mass

Question 7

What are the risk factors for colorectal cancer?

Answer 7

• Increasing age
• Adenomatous polyposis coli (APC) mutation (FAP)
• Lynch syndrome (HNPCC)
• MYH-associated polyposis
• Hamatomatous polyposis syndromes
• IBD
• Obesity

Question 8

When would you send patients down the 2WW pathway?

Answer 8

• > 40 with unexplained weight loss and abdominal pain
• > 50 with unexplained rectal bleeding
• > 60 iron-deficiency anaemia or changes in bowel habit

Question 9

How do you diagnose colorectal cancer?

Answer 9

• Barium enema or Colonoscopy
• CT colonography
• PET

Question 10

What is CEA (carcinoembryonic antigen) used for?

Answer 10

Predicts and detects recurrence of colorectal cancer

Question 11

Who is screened for colorectal cancer and how often?

Answer 11

• Aged 60-74, 2-yearly

Question 12

If the faecal occult blood test is +ve, what is done next?

Answer 12

Colonoscopy

Question 13

What are the inherited CRCs with polyposis?

Answer 13

• Familial Adenomatous Polyposis (FAP)
• Peutz Jeghers Syndrome (PJS)
• Juvenile Polyposis Syndrome (JPS)
• MUTYH Associated Polyposis (MAP)

Question 14

What is the inherited CRC without polyposis?

Answer 14

Hereditary Non-Polyposis Colorectal Cancer (HNPCC) /Lynch syndrome

Question 15

What is Familial Adenomatous Polyposis (FAP)?

Answer 15

• Autosomal dominant mutation in the APC tumour suppressor gene
• Causes multiple colorectal adenomas which undergo malignant transformation
• CRC in 20-30s

Question 16

What is K-ras?

Answer 16

• Oncogene (gain of function)

Question 17

What is P53?

Answer 17

• Tumour suppressor gene (loss of function)

Question 18

What is MUTYH Associated Polyposis (MAP)?

Answer 18

• Autosomal recessive mutation in MUTYH

- Proximal colon cancer

Question 19

What is Peutz Jeghers Syndrome (PJS)?

Answer 19

• Autosomal dominant mutation in STK11
• Multiple hamartomatous polyps in the small intestine and colon
• Melanin pigmentation of the lips, mouth and digits

Question 20

What is Juvenile Polyposis Syndrome (JPS)

Answer 20

• Autosomal dominant mutation in SMAD4

- Mucus-filled hamartomatous polyps are found in the colorectum

Question 21

What is Hereditary Nonpolyposis Colorectal Cancer (HNPCC) / Lynch Syndrome?

Answer 21

• Autosomal dominant mutation in mismatch repair (MMR) genes
• More likely to be right-sided
• Onset 30-50s

Question 22

What other cancers does Hereditary Nonpolyposis Colorectal Cancer (HNPCC) / Lynch Syndrome make patients at higher risk of developing?

Answer 22

• Endometrial cancer (most common)
• Ovary
• Stomach
• Small intestine
• Hepatobiliary tract
• Urinary tract

Question 23

What is the preventative treatment for HNPCC/ Lynch syndrome?

Answer 23

Aspirin 150-300mg o.d.