7.7 Damaging Effects of Chemotherapy on the Digestive System

Question 1

Broadly, what do all chemotherapies have in common in terms of target?

Answer 1

They target processes that cancer cells have exploited:
- Rapid cell division
- Resistance to apoptosis/hypoxia
- Loss of checkpoint inhibition

Question 2

Which kinds of cells are more at risk of damage during chemotherapy? Why?

Answer 2

• Chemo kills cancer cells by interrupting their cell cycle
• Other cells that replicate quickly, therefore, are also damaged, incl. GI mucosa, hair follicles, and bone marrow

Question 3

True or false: since cancer is more dangerous than malabsorption, GI damage is not considered significant in the setting of chemotherapy

Answer 3

• False
• GI damage is dose-limiting

(If you have cancer, you might die. If you can’t eat, you will die.)

Question 4

True or false: the submucosa contains the lamina propria

Answer 4

• False
• The lamina propria, basement membrane, and epithelium are all part of the mucosa itself

Question 5

Which layer of the oral/gi mucosa is most likely to be sensitive to chemotherapy? Why?

Answer 5

• Base of the epithelium
• These are the most rapidly dividing cells, since they replicate to produce the mucosal lining

Question 6

What are the three types/proportions of oral mucosa? Where are they found? Which kind is most vulnerable to mucositis?

Answer 6

1. Masticatory (25%): important in chewing. Found on hard palate, ginigiva
2. Lining (60%): covering areas subject to movement; soft palate, floor of mouth, cheeks etc.
3. Specialised (15%): dorsum of tongue

Lining mucosa is most vulnerable to mucositis (which is unfortunate, since it’s also the most common)

Question 7

Explain how the GI tract is affected by chemo, and how this leads to mucositis

Answer 7

• Medication/radiation generates ROS, and triggers a cascade of downstream events
• Increased inflammatory cytokines, apoptosis, tissue injury, and DNA injury, all of which kill cells
• This cascade feeds back on itself
• Epithelium breaks down, leading to bacterial invasion, causing immune activation (bacteraemia/sepsis risk in the setting of immunosuppression)

Question 8

What treatment, under what circumstances, is indicated for treatment/prevention of oral mucositis during chemo?

Answer 8

• 30min of oral cryotherapy
• Given to patients during infusion of CT

Question 9

What are some general ways of preventing mucositis in chemo patients?

Answer 9

• Avoid alcohol/spicy foods
• Regularly brush teeth

Question 10

Mucositis treatment

Answer 10

• Analgesia
• Saliva replacements
• Mouthwashes to clean/numb mouth