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Table of Contents |
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Introduction |
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Although pain isn't always a prominent feature of cancer,
it's one of the most feared symptoms. Nowadays there's no reason that
most patients with cancer pain cannot be made comfortable. Apart from
pills, there are many different ways of tackling the problem, so that
pain shouldn't be the major concern of the patient with cancer. However,
this sort of assurance requires an efficient cancer management team
and attentive caregivers.
The first step in managing cancer pain is proper evaluation, and
the review summarized here outlines the principles involved.
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Assessment of cancer pain |
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There are various types of pain in cancer - that due to injury
of tissues around the tumor (called nociceptive pain), the tumor's
stimulation of nerves (called neuropathic pain), and individual
mental responses to sensation from the tumor (psychogenic pain).
Not surprisingly, self-reporting by the patient is the most important
way to assess the pain.
A full history, physical exam, and appropriate lab and imaging
studies (X-ray, CT, MRI) should reveal how the disease process is
producing pain. But the time- course, its intensity, its features,
and what makes it better or worse are all important in helping decide
the best strategy for treatment.
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Acute pain |
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There are various types of pain in cancer - that due to injury
of tissues around the tumor (called nociceptive pain), the tumor's
stimulation of nerves (called neuropathic pain), and individual
mental responses to sensation from the tumor (psychogenic pain).
Not surprisingly, self-reporting by the patient is the most important
way to assess the pain.
A full history, physical exam, and appropriate lab and imaging
studies (X-ray, CT, MRI) should reveal how the disease process is
producing pain. But the time- course, its intensity, its features,
and what makes it better or worse are all important in helping decide
the best strategy for treatment.
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Chronic pain |
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The most common cancer pain is due to bone pain. It
is not known why some bone metastases are painless, and others are
painful. If the spine is involved, there may be damage to the spinal
cord or nerve roots. Other chronic pain conditions are due to neuropathic
pain (e.g. post-mastectomy pain due to surgical damage to a nerve)
or following radiation (fibrosis involving a nerve). Chemotherapy
can sometimes cause persistent neuropathic pain, which stops when
the chemo is discontinued.
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Associated factors |
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Suffering by cancer patients is not limited to the awareness of
pain. Additional problems - e.g. fatigue, misery, and social difficulties
- must also be considered when managing pain. A team of different
health professionals is best able to cover all the aspects involving
the patient's quality of life, not just physical and psychological
well-being, but also household, social, spiritual, and financial
matters. Hospice programs are particularly suitable in this regard.
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Drug treatment - the opioids |
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The mainstays of pain relief in cancer remain the derivatives
of morphine, called opioid derivatives. One of the best guidelines
for selecting the drug, route of administration, dose, frequency of
dosing, and so on, is the 'analgesic ladder' recommended by the World
Health Organization (WHO).
The choice of drug will depend on age, the presence of liver or
kidney disease, possible interactions with other medications, etc.
The oral route is usually preferred, but other routes (for instance,
the transdermal skin patch) can be used if there is difficulty in
swallowing or any severe gastrointestinal upset.
For continuous or frequently recurring pain, it's usually best
to have a fixed schedule for dosing - e.g. every 4 hours - rather
than giving the drug 'as needed'. Starting low, dosing is increased
until pain relief is achieved or side effects prevent such an increase.
If pain 'breaks through' the schedule, a 'rescue' dose can be added
immediately; rescue dose levels are typically 5 -15% of the total
daily dose of the drug
Oral doses can be given more often, if necessary, with as little
as 1½ - 2 hours between doses; the minimum interval between
intravenous (IV) administration can be as short as 10 - 15 minutes.
It's important for everyone to know that there's no 'correct' dose
or 'maximum' dose for cancer patients; the correct dose is simply
'enough'.
Development of side effects does not prevent further increase in
doses; the treating physician can prescribe medications or other
therapies to counteract the most common problems seen with opioids
- nausea, vomiting, and constipation.
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Non-opioid analgesics |
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Acetaminophen and non-steroidal anti-inflammatory drugs
(NSAIDs, such as ibuprophen) are good painkillers, but they have a
'ceiling dose level' above which no more benefit can be expected.
They are most useful in people with bone pain, or inflammatory pain,
where the affected area is warm, red, and swollen. The newer COX-2
inhibitors may be superior types of NSAIDs in avoiding possible gastric
or kidney toxicity.
Some drugs that are not primarily painkillers may have pain-relieving
activity as well as their main effect. For instance, steroids, antidepressants,
some anesthetics, anti-epilepsy drugs, and major tranquilizers may
each be helpful in various cases of neuropathic pain. They are usually
given after opioid therapy has been stabilized. In addition, certain
types of cancer may do well with a particular drug directed at the
tissue involved - e.g. bisphosphonates (such as Fosamax) or calcitonin
for bone pain.
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Radiation and chemotherapy |
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In addition to its main use (destruction of cancer
cells), radiotherapy is often used for pain control, chiefly in managing
bone metastases from lung, breast or prostate cancers; the response
is usually good (70% to 80% of patients). Chemotherapy can provide
pain relief in pancreas and prostate cancer due to tumor shrinkage;
but there's often the problem of balancing this sort of improvement
against the toxic effects that chemotherapy can produce. |
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Non-drug therapy |
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There are plenty of alternative treatments for cancer
patients whose pain is not adequately controlled by medication. These
are mostly done by specialists in hospital settings. The commonest
ones are:
- Epidural opioid injections
- Continuous spinal local anesthesia
- Nerve blocks
- Acupuncture
- Exercise, heat or cold treatment
- Relaxation classes, hypnosis
- Individual, group, or family psychological therapy
A cancer treatment center or pain clinic is probably the best place
for getting information and advice on these therapeutic approaches,
if the patient's cancer management team does not offer them. |
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Alternative Medicine |
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Alternative (or Complementary) Medicine is becoming
increasingly popular in the search for cancer pain relief, but few
well-controlled studies have been done showing that such methods are
truly effective. Physicians are likely to be open to a trial of such
treatments, and be supportive if patients select one that is considered
to be safe.
Source
- Trends in Cancer Pain Management P. Lesage, RK. Portenoy, Cancer
Control, 1999, vol. 6, pp. 136--145
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