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CANCER PAIN
Cancer pain is an unpleasant sensory & emotional experience due to actual or potential tissue damage in patients with cancer.
Effective pain management in cancer patients with pain is an essential part of oncologic management due to increasing evidence of survival.
Pancreatic, head & neck cancer has a high prevalence of cancer pain.
During initial evaluation, follow-ups and new therapy initiation of patients with cancer, it is essential that they will be screened & evaluated for pain.

Diagnosis

  • All cancer patients should be screened for pain at each contact

Types of Pain

Nociceptive Pain

  • Caused by ongoing tissue damage to somatic &/or visceral structures that results in the activation of nociceptors found in the skin, viscera, muscle & connective tissues
  • Can be subclassified as:
    • Somatic pain that often occur after surgical procedures or from bone metastasis
      • The pain is described as sharp, aching, stabbing, well localized, throbbing & pressure-like
    • Visceral pain is caused by tumor involvement of organ causing pain, may also be due to compression, infiltration or distension of abdominal or thoracic viscera
      • The pain is described as more diffuse & difficult to localize; gnawning or cramping if secondary to obstruction of hollow viscus; aching, sharp or throbbing when due to tumor involvement of organ capsule

Neuropathic Pain

  • Sustained from peripheral or central nervous system damage or dysfunction
  • Pain described as burning, pricking, electric-like, stabbing, sharp or shooting & sometimes may have a deep aching component
  • Pain is usually located in the area innervated by the compressed/damaged peripheral nerve, plexus, nerve root or spinal cord that is often associated with loss of sensation in the painful region
  • Allodynia or dysesthesia may be present
  • Please see the disease management chart Neuropathic Pain for more information

Breakthrough Pain

  • Pain that occurs even when pain is adequately treated or even in a relatively well controlled baseline pain
    • It has rapid onset, moderate to severe in intensity & relatively short in duration (median 30 minutes)

Incident Pain

  • Pain that occurs after a specific activity or event
  • Rescue doses of short-acting opioids are given in anticipation of those events
  • Rescue doses is usually between 1/12 & 1/6 of the total 24-hours dose

End-of-Dose Failure Pain

  • Pain that occurs toward the end of dosing interval for regularly scheduled opioid
  • Regularly scheduled opioid dose or frequency are increased to manage this type of pain

Uncontrolled Persistent Pain

  • Pain that occurs due to inadequate management of existing regularly scheduled opioid
  • Dose schedule adjustment are done to manage this kind of pain

Assessment

  • In order to manage cancer pain effectively, comprehensive assessment of pain is a necessary first step
  • It is important that the intensity of pain be quantified & qualitatively described by the patient itself whenever possible
  • Aside from using pain rating scale, pain assessment includes:
    • Location, referral pattern, & radiation of pain 
    • Quality of pain
    • Presence of breakthrough pain
    • Current & prior non-pharmacologic & pharmacologic treatments used & their impact on pain
    • Adequate comfort, satisfaction with pain relief
    • Provider assessment of adequacy of function
    • Any special issues for the patient relevant to pain treatment
  • Behaviors & discomfort (ie facial expression, body movements, verbalization or vocalizations, changes in interpersonal interactions, changes in routine activity) can also be a way of assessing presence of pain
  • Pain assessment aims to determine:
    • Nature & pathophysiology of pain
    • Pain severity
    • Impact of pain on functions & quality of life
    • Response to interventions
  • Numerical levels of pain intensity or pain scores are:
    • 1-3 is mild
    • 4-6 is moderate
    • 7-10 is severe

Pain Assessment Tools

  • Used in assessing the intensity of pain & the effectiveness of management

Unidimensional Assessment Tools

  • Reliable, easily implemented (with minimal training) & sustained in outpatient practice
  • Numerical rating scale may be done by verbally asking the patient to describe the pain from 0-10 with 10 as the worst pain or by asking the patient to write or encircle the number that describes the intensity of pain experience
  • Categorical scale can be done by asking the patient to give a word or words that describes the pain experience
  • Visual Analogue/Pictorial/Faces pain rating scale is done by assessing the facial reaction of the patient to pain

Multidimensional Assessment Tools

  • Reliable, but needs more evidence in regards to validity
  • Brief Pain Inventory (BPI) is the most frequently used
    • Assess the severity of pain by its intensity & how it affects the patient’s life
    • Quantifies these measures using a 0 to 10 numerical scale
  • EORTC QLQ-C30 Pain Scale, SF-36 Bodily Pain Scale & the Short Form McGill Pain Questionnaire are other multidimensional scales used

Psychosocial Assessment

  • Psychosocial distress assessment should be done as pain is an important stressor in all kinds of cancers that can cause psychological distress & disability
  • Inadequately controlled pain may cause substantial psychological distress
  • Validated tools should be used in screening for psychological distress

History

  • It is essential to have a good history taking for accurate assessment & diagnosis of causes of pain
  • History should consists of:
    • Characteristics of pain: location, intensity, frequency
    • Cancer history: type & staging of carcinoma, chemotherapeutic regimen & duration
    • Medication: prior treatments received for pain, maintenance treatments
    • Co-morbidities
    • Psychosocial status

Physical Examination

  • Confirms the clinical diagnosis formed after comprehensive history taking
  • Gives information on the patient’s condition & extent of problems
  • Neurological exam should be done in patients with suspected neuropathic pain

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