Cancer of the GIT

Question 1

List 6 characteristic hallmarks of cancer.

Answer 1

1 - Evasion of apoptosis.

2 - Self-sufficiency in growth signals.

3 - Insensitivity to anti-growth signals.

4 - Tissue invasion and metastasis.

5 - Limitless replicative potential.

6 - Sustained angiogenesis.

Question 2

List the two types of oesophageal cancer.

Answer 2

1 - Adenocarcinomas (ADCs).

2 - Squamous cell carcinomas (SCCs).

Question 3

List 6 risk factors for oesophageal ADCs.

Answer 3

1 - Reflux and Barrett’s metaplasia.

2 - Gender.

3 - Age.

4 - Lower oesophageal sphincter (LOS) relaxing drugs.

5 - Obesity.

6 - Helicobacter pylori.

Question 4

How do cells change in Barrett’s metaplasia?

Answer 4

Cells lining the oesophagus change from stratified squamous to simple columnar.

Question 5

What is the most important risk factor for gastric cancers?

Answer 5

Helicobacter pylori.

Question 6

List the areas of the stomach and briefly describe their locations.

Answer 6

1 - Cardia (oesophageal opening).

2 - Fundus (bulbous superior portion).

3 - Body / corpus.

4 - Antrum (inferior portion).

5 - Pylorus (funnels into duodenum).

Question 7

What are the effects of H. pylori infection in the antrum of the stomach?

Answer 7

• Hypergastrinaemia.

- Duodenal ulcers.

Question 8

What are the effects of H. pylori infection in the body of the stomach?

Answer 8

• Reduced acid secretion.
• Hypochlorhydria.
• Gastric ulcers.

Question 9

What does treatment-triple therapy consist of?

Answer 9

1 - Amoxicillin (antibiotic).

2 - Clarithromycin (antibiotic).

3 - A proton pump inhibitor.

Question 10

List 5 ways by which H. pylori cause its effects.

Answer 10

1 - Urease neutralises gastric acid, causing gastric mucosal injury by ammonia.

2 - Lipopolysaccharides cause inflammation.

3 - Type 4 secretion systems inject effectors that inhibit apoptosis.

4 - Secretory enzymes such as mucinase, protease and lipase cause mucosal injury.

5 - The exotoxin vacA causes mucosal injury.

Question 11

What is hereditary diffuse gastric cancer?

Answer 11

An autosomal dominant susceptibility for diffuse gastric cancer that causes a thickening of the stomach wall.

Question 12

What are the two histological types of adenocarcinoma?

Answer 12

Intestinal type and diffuse type.

Question 13

What causes hereditary diffuse gastric cancer?

Answer 13

Germline mutations in the CDH1 gene.

Question 14

What is e-cadherin?

Answer 14

A molecule that is important in the formatino of adherins junctions.

Question 15

List the types of cell junctions.

Answer 15

1 - Tight junctions (zonula occludens).

2 - Adhering junctions (zonula adherens, desmosomes and hemidesmosomes).

3 - Gap junctions.

Question 16

List 3 causes of e-cadherin repression.

Answer 16

1 - Epigenetic events.

2 - Promoter hypermethylation.

3 - Epithelial to mesenchymal transition (EMT) regulators.

Question 17

What is epithelial to mesenchymal transition (EMT)?

Answer 17

The process whereby epithelial cells are transformed into mesenchymal cells.

Question 18

List two risk factors for colorectal cancer.

Answer 18

1 - Older age.

2 - Meat intake.

3 - Obesity.

4 - Alcohol.

Question 19

List 4 ways in which colorectal cancer risk can be reduced.

Answer 19

1 - High fibre intake.

2 - High fish consumption.

3 - Exercise.

4 - Aspirin and other NSAIDs.

Question 20

What are the types of colorectal cancer?

Answer 20

Sporadic and familial.

Question 21

List the types of familial colorectal cancer.

Answer 21

1 - Familial adenomatous polyposis (FAP).

2 - Hereditary nonpolyposis colorectal cancer (HNPCC) / Lynch syndrome.

Question 22

How does familial adenomatous polyposis (FAP) cause colorectal cancer?

Answer 22

• The increased risk is due to polyp formation, which are benign but can become malignant.
• The polyp formation is due to a mutation to the APC (adenomatous polyposis coli) gene.

Question 23

How does hereditary nonpolyposis colorectal cancer (HNPCC) cause colorectal cancer?

Answer 23

The increased risk is due to mutations that impair DNA mismatch repair.

Question 24

How is familial adenomatous polyposis (FAP) treated?

Answer 24

Prophylactic surgery.

Question 25

What is the difference between a carcinoma, a squamous cell carcinoma, an adenocarcinoma and an adenoma?

Answer 25

• A carcinoma originates from epithelial cells.
• A squamous cell carcinoma originates from squamous cells.
• An adenocarcinoma originates from glandular tissue.
• An adenoma is the benign counterpart to an adenocarcinoma.

Question 26

List two drugs that can be used to treat colorectal cancer.

Answer 26

1 - Metformin.

2 - Cetuximab.

Question 27

What role does iron play in the formation of cancer?

Answer 27

• Excess iron can contribute to tumour initiation and growth.
• Iron’s capacity to gain and lose electrons enables it to participate in free radical-generating reactions.