41 – Chronic Cancer Pain Flashcards

1
Q

What is cancer pain?

A
  • Pain arising from damage to the body by cancer and from body’s response to cancer
  • *best addressed by treating the cancer
  • Ex. hyperalgesia, allodynia, ongoing pain, breakthrough pain
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2
Q

When does cancer pain become chronic?

A
  • When cancer cannot be cured or adequately controlled
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3
Q

What are the mainstays of cancer treatment?

A
  • Surgery
  • Radiation therapy
  • Chemotherapy
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4
Q

EXAMWhat is the primary goal of palliative radiation treatment?

A
  • Alleviate pain or discomfort associated with an incurable tumor
  • clear definition of palliative intent cancer treatment with radiation
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5
Q

Osteosarcoma and mechanical stimulation (tumor)

A
  • Increased pressure within in
  • Microfractures
  • Stretching of periosteum
  • Compression of nerves due to collapse of bone
  • Reactive muscle spasm
  • Nerve root infiltration
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6
Q

Osteosarcoma and chemical stimulation (tumor and body)

A
  • Prostaglandins
  • Inflammatory cytokines (Ex. GFs, interferons, CSFs)
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7
Q

Canine appendicular osteosarcoma

A
  • Most COMMON primary bone tumor
  • Locally invasive to highly metastatic to distant sites
    o By the time you see them 95% have metastaized
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8
Q

What is the definitive treatment of canine appendicular osteosarcoma?

A
  • Surgery (amputation, limb spare) OR
  • Radiation for primary tumor
  • Chemotherapy to delay distant metastases
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9
Q

EXAMRank the effectiveness of pain relief for radiation, surgical and medical therapies for canine osteosarcoma

A
  • Amputation removes source of pain
  • Stereotactic radiation therapy (SRT) alleviates pain
    o Reduces mechanical and chemical stimulation of nociceptors
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10
Q

EXAMHow do dog owners feel about amputation for canine osteosarcoma?

A
  • Very happy: 98%
  • Even if the animals did not live long afterwards, they did not mind it
  • *quality of life!
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11
Q

What are some reasons for not doing amputation or SRT?

A
  • Owners do not want to
  • Patient NOT a good candidate for amputation
  • Recurrent tumor
  • Metastatic to other bones
  • *multimodal analgesia and multimodal treatment
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12
Q

EXAMWhich pain-relieving drugs are best suited to long-term, outpatient pain control?

A
  • Metacam
  • Gabapentin
  • Amantadine
  • Zoledronate (EXPENSIVE)
  • *details to come
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13
Q

Drugs to decrease inflammation

A
  • NSAIDs inhibits COX
    o *first drug used for cancer pain!
  • Meloxicam, deracoxib
  • Grapiprant
  • NOT used in patients that are on a steroid
  • *generally well tolerated, narrow range of dosing, EXPENSIVE ($85/month)
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14
Q

Drugs to decrease pain signal transmission

A
  • Gabapentin ($38/month)
  • Amantadine ($70/month)
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15
Q

What are other pain drugs

A
  • Tramadol
  • Fentanyl patches
  • Bisphosphonates
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16
Q

Tramadol

A
  • Mu agoinst, alpha 2 agonist
  • *serotonin reuptake inhibition
  • Side effects: sedation, agitation
  • Do NOT use with SSRI
  • Efficacy is questionable
  • Expensive ($176/month)
17
Q

Fentanyl patches

A
  • Side effects: sedation, agitation, inappetence, dysphoria
  • *use in outpatients can be challenging
  • Can de difficult to distinguish between side effects and pain
18
Q

Bisphosphonates

A
  • Induces apoptosis of tumour cells
  • Inhibits tumour cell proliferation
  • Antiangiogenic
  • Renal effects, low risk of bone necrosis
  • In-hospital administration: expensive
  • Ex. Zoledronate (especially for bone disease)
19
Q

EXAMWhat are the indications to palliative radiation treatment of chronic cancer pain (e.g., canine osteosarcoma)?

A
  • Goal to alleviate pain or discomfort from an incurable tumour?
  • Does pet’s family fully understand the goal of treatment?
  • Is the tumour the source of clinical symptoms?
  • Is the patient’s condition stable enough for radiation treatment?
20
Q

EXAMWhat are the contraindications to palliative radiation treatment of chronic cancer pain (e.g., canine osteosarcoma)?

A
  • Probability of pain improvement is low and euthanasia is recommended
  • *Metastatic disease (distant or regional) is NOT a contraindication to treatment
    o Ex. lung mets=do NOT cause pain
21
Q

How does radiation therapy work?

A
  • Photons (x-rays) damage DNA leading to cell death
  • Direct killing of tumour cells
  • Direct killing of host cells
  • *decrease in mechanical and chemical stimulation of nociceptors
22
Q

Outcome of palliative radiation with osteosarcoma

A
  • Pain relief ranges from 2-4 months
  • Median survival: 4-10months
  • 74-96% experience pain relief
23
Q

Outcome of palliative radiation with canine oral melanoma

A
  • Overall response rate of 80%
    o 50% complete remission
    o 30% partial remission
  • median survival: 8 months
24
Q

Outcomes of palliative radiation therapy: overall

A
  • do NOT look at survival time for ‘relief’ of pain
    o very owner influenced!
  • Need pain scales
  • *best endpoint to assess success of treatment of chronic pain=quality of life