Oncology 3 Flashcards

1
Q

General principles of chemotherapy.

A
  • Owner factors.
  • Patient factors.
  • Indications.
  • Dose and timing.
  • Drug resistance.
  • Safe handling.
  • Toxicity.
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2
Q
  1. Give some examples of patient factors.
  2. Give some examples of owner factors.
A
  1. Age. current health, current med, allergies, temperament.
  2. Owner ability to care, cost, owner current health, pregnancy.
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3
Q

What are indications for chemotherapy?

A
  • Chemo-sensitive tumours.
  • Often used as primary therapy for haemopoietic malignancies e.g. lymphoma.
  • As adjunctive therapy e.g. following surgery, for solid tumours – eradicates or manages metastatic disease.
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4
Q

Why do we not use chemotherapy for treatment of solid tumours?

A

Most chemotherapeutic agents act upon processes in cell growth and division e.g. DNA replication, mitotic spindle.
– Rapidly dividing cells most susceptible, and those in resting phase of cell cycle (G0) are most resistant.
–> These G0 cells can act as ‘reservoir cells’ that can re-populate unless there is complete surgical excision.
- Ideally use chemo when growth fraction is at its highest e.g. early in disease process or after debulking.

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5
Q

Why is dosing and timing of chemo so important?

A

To work, chemo drug must reach the cancerous cells, exert a cytotoxic effect within the cell and resistance must not develop.

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6
Q

What are the determining factors for the drug reaching the cancerous cells, exerting cytotoxic effect and not allowing resistance to develop?

A

Whether a single or multiple agents used.
Drug(s) given and the mech of action.
Dose.
Timing of administration.

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7
Q
  1. Pros of single agent chemo.
  2. Cons of single agent chemo.
A
    • Decreased cost.
      - Decreased risk of toxicity.
      - Decreased time in hospital.
    • Decreased efficacy.
      - Drug resistance develops faster.
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8
Q
  1. Pros of multiple agent chemo.
  2. Cons of multiple agent chemo.
A
    • Greater efficacy.
      - Drug resistance develops slower.
    • Increased cost.
      - Increased risk of toxicity.
      - Increased time spent in hospital.
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9
Q

Platinum compounds…
1. MoA.
2. Examples.
3. Example uses.

A
  1. Cross-linking and damaging DNA, inhibiting replication.
  2. Cisplatin, carboplatin.
  3. Osteosarcoma.
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10
Q

Alkylating agents…
1. MoA.
2. Examples.
3. Example uses.

A
  1. Cross-links DNA, inhibiting replication and transcription.
  2. Cyclophosphamide, lomustine, chlorambucil.
  3. Lymphoma, multiple myeloma.
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11
Q

Anti-metabolites…
1. MoA.
2. Examples.
3. Example uses.

A
  1. Inhibit use of cellular metabolites during growth/division.
  2. Cytarabine, azathioprine, methotrexate.
  3. Lymphoma and leukaemia.
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12
Q

Anti-tumour antibiotics…
1. MoA.
2. Example.
3. Example use.

A
  1. Several.
    Incl. promotion of free radicals and inhibition of enzymes required for DNA replication.
  2. Doxorubicin.
  3. Lymphoma.
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13
Q

Tyrosine kinas inhibitors…
1. MoA.
2. Examples.
3. Example uses.

A
  1. Inhibit tyrosine kinase, which when activated, leads to aberrant cell growth. Used to treat tumours expressing c-kit mutation.
  2. Masitinib, toceranib.
  3. MCTs, GI stromal tumours.
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14
Q

Enzyme…
1. MoA.
2. Example.
3. Example use.

A
  1. Destroys circulating asparagine necessary for protein synthesis.
  2. L-asparaginase.
  3. Lymphoma.
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15
Q

Plant alkaloids…
1. MoA.
2. Examples.
3. Example uses.

A
  1. Disable mitotic spindle.
  2. Vincristine and vinblastine.
  3. Lymphoma and MCT.
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16
Q

NSAIDs…
1. MoA.
2. Examples.
3. Example uses.

A
  1. Induce apoptosis.
  2. Piroxicam, Meloxicam.
  3. Transitional cell carcinoma, colonic adenocarcinoma.
17
Q

Glucocorticoids…
1. MoA.
2. Example.
3. Example use.

A
  1. Cytotoxic to lymphocytes and decrease lymphocyte proliferation.
  2. Prednisolone.
  3. Lymphoma.
18
Q

Immunotherapy…
1. MoA.
2. Example.
3. Example uses.

A
  1. Causes antibody production that cross react w/ canine tyrosinase which is essential for melanin synthesis.
  2. Melanoma vac.
  3. Digit and oral melanoma.
19
Q

What is the purpose of combining chemo drug classes?

A

To increase efficacy of treatment whilst helping to avoid side effects.
This helps balance effective dosing with causing limited harm.

20
Q

What areas of the body are most commonly affected by chemo and why?

A

Bone marrow and gut epithelium – rapidly dividing cells here.

21
Q
  1. By which order kinetics do chemotherapeutics act?
A
  1. First order. – kill a fixed percentage of cells opposed to set number.
22
Q

What factors of timing affect treatment outcome?

A

Promptness of beginning treatment and regularity of treatment.

23
Q
  1. Primary drug resistance.
  2. Secondary drug resistance.
A
  1. Cancer resistant to drug in the first place.
  2. Develops due to mutation and selection of resistant clones.
24
Q
  1. With what aim may prednisolone be prescribed?
  2. Downfall of pre-treatment preds?
A
  1. Palliative care before definitive dx.
    A light touch chemo option for some cancers e.g. lymphoma.
  2. Helps drug resistance to develop more swiftly. – may be due to increased expression of proteins with multi-drug resistance potential e.g. MDR-1. –> codes for production of a protein called ‘p-glycoprotein’ which is able to pump some chemotherapeutic drugs out of cell.