Pain management in cancer patients (Proceedings)

Pain in Cancer

• Cancer is often a painful disease

• ⅓ of all human cancer patients report pain (60-90% with advanced cancer)

• 70-90% can achieve "good" pain control

• In human patients, pain is often more feared than death

• extension of these same concerns by owners to their pet's cancer

Optimal Treatment

• understand the disease and extent

• recognize the cause and importance of each pain

• consider diverse management options

• staged pain management approach

• titrate, adjust and balance care to maintain the most appropriate control

Acute Cancer Related Pain

• surgical oncology, radiation therapy, "break-through" pain

"Chronic" pain

• pain of metastasis, treatment related pain

• palliative care and terminal cancer pain

• Pain in dying, aspects of suffering and the psychology of cancer

Analgesia in Cancer Surgery

• Pre-emptive, balanced multi-modal and adequate analgesia

• Value of local anesthetics in surgical oncology

o Injection of nerve sheath prior to transection (amputation)

• Brachial Plexus nerve block - effective distal to elbow

Clinical Assessment

• History - comprehensive

• Examine sites of pain and dysfunction thoroughly (may need analgesics!)

• Use appropriate diagnostic tools: (Radiography, Ultrasound, CT, MRI, Nuclear Scintigraphy) Advanced techniques can be very helpful.

Clinical Assessment

• Evaluate extent of disease - extent of pain

• Treat the pain early and aggressively to fully gain control early

• Watch for development of tolerance (specifically to opioids) and side effects (can be managed)

"Acute" Cancer Pain

• associated with tumor involvement

o compression, erosion, nerve compromise

o paraneoplastic syndromes

• surgery or other procedures

• importance of operative pain management can not be overstated

o operative pain management is often the first opportunity we have

"Chronic" Cancer Pain

• more difficult to diagnose and to treat

• longer duration, less well defined onset

• may be associated with hypersensitivity

• may increase with tumor progression

• may subside during periods of tumor regression

• associated with a negative quality of life

Types of Pain in Cancer

• somatic, visceral, neuropathic, inflammatory

Somatic Pain in Cancer

• more acute and specific in nature

• nociceptor activation: sharp, aching, throbbing or pressure-like

• metastatic bone pain, post surgical pain, musculoskeletal pain

Visceral Pain in Cancer

• less well localized

• nociceptors of thoracic, abdominal or pelvic viscera

• diffuse gnawing or cramping, aching or throbbing

Neuropathic Pain in Cancer

• central or peripheral nerve involvement

• infiltration or compression of nerves

• phantom limb syndrome

• corticosteroids, decompression, neurolysis

Inflammatory Mediators

• "alogenic" chemical mediators

• histamine, serotonin, bradykinins, leukotrienes, prostaglandins

Inflammatory Pain in Cancer

• NSAID's, corticosteriods

• treatment of paraneoplastic syndromes

Cancer Pain Management Influences all these as Focal Issues

• Prognosis, Costs, Quality of life, Willingness to treat

Perioperative Analgesic Therapy

• Combined strategies, balanced analgesia

• surgical excision, radiation therapy, chemotherapy, immunotherapy

WHO Treatment Strategy

• relies on intensity and severity rather than mechanism and etiology

• individualized and titrated management

• escalation of analgesic strategies

• three (or four) levels of intervention:

o mild, moderate, severe, (refractory)

WHO Analgesia Ladder - Step one - Mild Pain

• NSAID's, acetaminophen

• many individual options for dogs and cats

• ± adjuvants (GI protective)

• misoprostol, H2 blockers, H+ blockers, etc.

WHO Analgesia Ladder - Step two - Moderate Pain

• NSAID's plus mild opioids, many options

• add low dose weak or partial agonist

WHO Analgesia Ladder - Step three - Severe Pain

• Stronger opioid, perhaps added to NSAID

WHO Analgesia Ladder - Step four - Refractory Pain

• alternative routes of delivery, interventions,

• blocks, neural stimulations, neurolysis

Maintain Quality of Life - Human/Animal Bond

• Appetite

• Activity

• Involvement

• Function

Palliative Care Includes Planning for Death

• Hospice care

• Progression of disease

• Unmanageable pain

• Unmanageable side-effects

• Toxicities from therapy

• Concurrent diseases

• Euthanasia as a part of cancer care

o Time for a "house call"

Terminal Care

• Often the most appreciated part of our interaction with the owners and animals

• When the time comes...