Chronic Cancer

Question 1

What is cancer pain?

Answer 1

-pain arising from damage to the body by the cancer and from the body’s response to the cancer

Question 2

Best way to address cancer pain?

Answer 2

Treat the cancer!
*cancer pain becomes chronic when it cannot be cured or controlled

Question 3

Cancer treatment options

Answer 3

-surgery
-radiation therapy
-chemotherapy

Question 4

Chronic cancer pain

Answer 4

-hyperalgesia-increased response to normal stimulus

-allodynia- pain response to something that would not normally cause pain

-ongoing pain-dull constant pain

-breakthrough pain- intermittent periods of extreme pain

Question 5

Goal of palliative treatment

Answer 5

-to alleviate pain or discomfort associated with an incurable tumour

Question 6

Pain of appendicular osteosarcoma

Answer 6

-nociceptors in periosteum, bone, and bone marrow

-tumour can cause mechanical stimulation by increasing pressure, microfractures, stretching periosteum, compression of nerves, reactive muscle spasm, nerve root infiltration

-chemical stimulation from tumour and the host body
>prostaglandins and inflammatory cytokines

Question 7

Canine appendicular osteosarcoma

Answer 7

-most common primary bone tumour
-locally invasive or highly metastatic to distant sites

Question 8

Treatment of canine appendicular osteosarcoma

Answer 8

-surgery (amputation, limb spare) OR stereotactic radiation for primary tumour
>amputation removes pain
stereotactic radiation therapy reduced mechanical and chemical stimulation of nociceptors

-chemotherapy to delay distant metastases

Question 9

Amputations of appendicular osteosarcomas

Answer 9

-short survival time for cancer amputees did not decrease satisfaction
-most felt functional status was satisfactory
-no change in dogs attitude after amputation
-most felt returned to normal QOL

Question 10

Chronic cancer pain treatment

Answer 10

Multimodal analgesia and multimodal treatment

Question 11

When would amputation or SRT not be a good treatment for canine appendicular osteosarcoma?

Answer 11

-owners dont want to pursue treatment
-patient no a good candidate for amputation
-recurrent tumour
-metastatic to other bones

Question 12

Anti inflammatory options

Answer 12

-NSAIDs- inhibit COXs resulting in less prostaglandins. Typically first drug for cancer pain
-eg. Meloxicam, deracoxib, grapiprant

-not used in patients that are on a steroid

-usually well tolerated, narrow range of dosing (label dose), potential for side effects, expensive

Question 13

Gabapentin

Answer 13

5-10mg/kg PO BID
-can increase to TID and dose
-sedation or ataxia can be dose limiting

Question 14

Amantadine

Answer 14

3-5mg/kg PO SID to BID

-agitation, diarrhea

Question 15

Tramadol

Answer 15

-Mu agonist, alpha 2 agonist, serotonin reuptake inhibition
-cannot give with serotonin reuptake inhibitors

-efficacy questionable, expensive

Question 16

Fentanyl patches

Answer 16

-side effects: sedation, agitation, inappetence, dysphoria

-use in outpatients can be challenging

-can be difficult to distinguish between side effects and pain

Question 17

Biophosphonates

Answer 17

-induce apoptosis of tumour cells, inhibit tumour cell proliferation, antiangiogenic

-renal effects, low risk of bone necrosis

-in hospital administration, expensive

Question 18

First line best treatment for appendicular osteosarcoma

Answer 18

-metacam, gabapentin, amantadine

-zoledronate once a month

Monthly drug costs= $798.39

Question 19

Contraindications of radiation therapy

Answer 19

• probability of pain improvement is low
  -euthanasia is recommended
  -metastatic disease is not a contraindication to treatment

Question 20

Radiation therapy

Answer 20

-Photons (x-rays) damage DNA leading to cell death
-direct killing of tumour cells
-direct killing of host cells

*Results in decrease in mechanical and chemical stimulation of nociceptors

Question 21

Palliative radiation protocols

Answer 21

800 cGy x 3-4 treatments once a week

400cGy x 5 treatments daily

800cGy x 2 treatments 24 hrs apart Boom-Boom protocol

Question 22

Outcomes of palliative radiation therapy

Answer 22

-74-96% of dogs experience some degree of pain relief

-median time to pain relief= 11-15 days
-median duration of pain relief ranges from 2-4mths
-median survival 4-10mths

Question 23

Study Paper outcomes

Answer 23

-many publications report disease specific or overall survival for palliative treatments

-survival time is a good endpoint for relief of pain

-pain scoring and QOL scoring are better endpoints

Question 24

Diagnostic tests for a suspected osteosarcoma

Answer 24

-Biopsy
-FNA
-Chest rads=lung mets will help with treatment decision