Oncology: Medical Therapies Flashcards

1
Q

What is chemotherapy?

A

Chemotherapy is genotoxic treatment of disease by the use of chemical substances

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2
Q

What are the different applications of chemotherapy?

A
  • Primary- sole- anticancer treatment
  • Adjuvant- after surgery ‘mop up’
  • Neoadjuvant chemotherapy- beofre surgery to shrink
  • Concurrent- with radiation to increase sensitivity of RT
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3
Q
  1. What cells does chemo target?
  2. How can cells act as reservoirs?
  3. What are the targets of chemo?
A
  1. Highly proliferating tissues
  2. Cells in G0 can repopulate
  3. DNA synthesis, RNA synthesis, protein synthesis, cell cycle progression
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4
Q

When is chemotherapy most and least effective?
What is the major cause of chemotherapy failure?

A
  • Most effective against rapidly dividing cells
  • Slow growing (indolent) typically resistant

Drug resistance casues failure

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5
Q

At which stage is chemotherapy most likely to be effective?

A

C- fast growing, smallest

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6
Q

How are tumours heterogenous?

A
  • Cancer is a result of genetic instability- leads to more varitaion
  • As they progress they become ‘subclones’
  • Therefore may be lots slightly different
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7
Q

What factors affect chemotherapy success?

A
  1. Growth fraction and mass doubling time
  2. Tumour cell heterogeneity
  3. Inherent tumour sensitivity
  4. Drug dosage
  5. Tumour blood supply/oxygenation
  6. Interval between treatments
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8
Q

How can drug resistance be minimised?

A
  • Treat as early as possible
  • Use standard protocols
  • Use correct doses
  • Administer agenst properly
  • At relapse act ASAP
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9
Q

What tumours should not be pre-treated with steroids?

A

Lymphoma or mast cells
Causes resistance

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10
Q

What factors influence choice of chemotherapy agents?

A
  • Clinical situation- indication, evidence of benefit
  • Owner goals- often palliative, balance between QoL and effect
  • Patient- signlamnet, co-morb
  • Dosing and schedule
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11
Q

What affects response and side effects of chemotherapy?

A
  • Administration- dose ability to enter blood if oral
  • Distribution- target site, cellular uptake (BBB, vasculature)
  • Metabolism- drug activation
  • Excretion- clearance
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12
Q

What tumour can recieve single agent chemotherapy?

A

Transmissible venereal tumour

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13
Q

How can polychemotherapy be achieved?

A

Sequential- several drugs at different times
Combined- several drugs at same time

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14
Q

With polychemotherapy what should they achieve together?

What should be avoided?

A

Should
* Have proven efficacy
* Different modes of action
* Affect different stages of cell cycle
* non-overlapping dose limiting toxicities
* not interfere

Should avoid
* Arbitrarily exclude one of the drugs from protocol
* Reduce drug dose

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15
Q

What routes of chemotherapy should be avoided?

A
  • Topical
  • Intratumoural
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16
Q

When can patients pose dosing problems?

A
  • Obese patients
  • Collies with drug sensitivities
  • Hepatic function compromise
  • Reduced renal function
17
Q

Why is dosing rate difficult?

A

High dose chemo has a narrow therapeutic window

Too low- ineffective
Too high- toxic

18
Q

When should chemotherapy dose be reduced?

A

Only lower as needed based on actual adverse effects

19
Q

What is the purpose of dose density?

A
  • Designed to allow recovery of normal tissues
  • Rapidly dividing tissue such as bone marrow and GI tract have tremendous capacity to repair rapidly
20
Q

What is the common first line chemotherapy protocol for a canine lymphoma?

A

CHOP
* vincristine, doxorubicin, cyclophosphamide, prednisolone

CEOP
* vincristine, epirubicin, cycloposphamide and prednisolone

21
Q

What is the common first line chemotherapy protocol for lymphoma in cats?

A

high dose COP
* vincristine, cyclophosphamide and prednisolone

22
Q

What should be assessed before chemotherapy?

A
  • Tolerance of previous treatment
  • Assess patient
  • Assess tumour status
  • Biochemistry- pre-protocol, every few months
  • Haematology prior to treatment
  • Urinalysis
23
Q

What chemotherapy planning needs to take place?

A
  • Risks and benefits with owner
  • Ensure- not pregnent, no very young children
  • Practice is sufficient to administer drugs safely
  • Appropriate PPE is available
  • Written owner info
24
Q

Prior to each chemotherapy treatment what do neutrophils and platlets need to be?

A

Neutrophils over 3 x 10^9/L
Platelets over 100 x 10^10/L

25
Q

What can occur with immediate toxicity?

A
  • Anaphylaxis
  • Cardiac arrythmia
  • Emesis
26
Q

What is acute tumour lysis syndrome?
How does it show?
How is it managed?

A

When large tumour burdent are rapidly destroyed- lymphoma

Acute kidney injury, electrolyte abnormalities

Early IVFT, managment of AKI

27
Q

What are the general side effects of chemotherapy?

A

BAG
* Bone marrow- low WBC 7-10 days
* Alopecia- uncommon in dogs/cats
* GI- not after first 4 days

28
Q

What causes GI toxicity
What can it cause?
What can the sequale be?

A

Direct damage to enterocytes

Anorexia, nausea, vomiting, diarrhoea

Disrupted musocal barrier increases risk of sepsis

29
Q

How is GI toxicity managed?

A

Pre-emptive home managment
* Maropitant
* Pre-treatment fasting
* Consider smectite

Supportive treatment for severe cases (prolonged/unwell)

30
Q

How can toxicity be caused 7-10 days post chemo?

How is it treated?

A

Damage to emerging haematopoetic cells
* dip in neutrophil counts, too low leads to risk of sepsis

Hospitalise until systemically well
Stop cytotoxic drugs
Supportive
If neutrophils low- ABs, dose reduction

31
Q

What are possible drug associated complications?

A
  • Cumulative cardiotoxicity- doxorubicin
  • Sterile haemorrhagic cystitis- cyclophosphamide : tx- furosemide
  • Hepatotoxicity- Lomustine
  • Nephrotoxicity- cisplatin, doxorubicin (cats)
  • Peripheral neuropathy- vincrisitne
  • Non-cadiogenic pulmonaty oedema- cisplatin (cats)
  • Fatal CNS signs-
32
Q

What does this image show?

What about chemo can cause this?

A

Extravasation of drugs
Very irritant

Doxorubicin, epirubicin
Vincristine/vinblastine

Catheter- Flush before removal

33
Q

How are extravasations treated?

A
  • If suspected- do not flush
  • Doxorubicin- apply cold packs, topical DMSO, consider surgical debridement
  • Vincristine- apply warm, compress, topical DMSO, hyaluronidase
34
Q
  1. What is metronomic chemotherapy?
  2. What is its main target?
  3. How is it often applied?
A
  1. Continuous low dose chemotherapy
  2. Angiogenesis
  3. Usually pallitavely or after MTD chemo
35
Q

What drugs are generally given for metronomic chemotherapy?

A

Low dose
Cyclophosphamide with piroxicam

36
Q

What is the action of tyrosine kinase inhibitors?

A

Inhibit the activation of specific signalling pathways involved in specific types of cancer

37
Q

What can tyrosine kinase inhibitors also effect?

A

Effect on angiogenesis
Toxicity
Need regular monitoring

Diarrhoea, vomiting, anorexia
Bone marrow suppression