Cancer is a major world health problem with
an increasing prevalence and with a high incidence of pain. Cancer represents
the second main reason of death, after diseases of the cardiovascular system.
Bonica estimated that with the first diagnosis of cancer approximately 50% of
the patients suffer from continuous pain. With the progression of the
underlying disease 75 – 90% have constant pain.
The pain is caused either directly by the
disease (e.g. invasive processes, metastases) or cancer treatment (e.g. adverse
effects of anticancer drugs), is disease related (e.g. herpetic neuralgia) or
related to coexistent disorders (e.g. ostoarthritis).
As defined by the IASP pain is an “unpleasant
sensory and emotional experience associated with actual or potential tissue
damage, or described in terms of
such damage”. However, pain is caused by psychological, cultural and
spiritual distress too. Those different aspects have to be taken into account
in the overall care of cancer pain patients.
One of the first and most successful
approaches in cancer pain treatment was achieved by a task force of the World
Health Organisation and the IASP in the beginning of the 80´s. They achieved an
international consensus on the use of drugs for cancer pain relief. The concept
was published first in 1986. The book “Cancer pain relief” has been published
in more than 28 different languages. The recommendations of the WHO are based
on few basic principles:
“By the mouth”: drugs should be given by oral
route whenever possible.
“By the clock”: drugs should be given in
regular intervals to ensure a continuos pain relief. The interval depends on
the pharmakokinetics of the analgesics, a prescription “as required” is not
adequate.
“For the individual”: The therapy should be
adjusted to the individual person to guarantee a maximum benefit and minimum
adverse effects.
“By the ladder”: therapy should start with a
non-opioid analgesic and with increasing or still unreleaved pain opioids
should be added. The analgesics should be combined with adjuvant drugs such as
antidepressants and anticonvulsives and symptomatic treatment (e.g. laxatives,
antiemetics) wherever indicated.
These recommendations have been evaluated in
several surveys in different settings The
validation of the WHO-guidelines demonstrated the simplicity of its
approach and the efficacy of the pain relief achieved. Analgesia was adequate in 69-88% of the cancer pain patients.
Unfortunately most of the studies
demonstrating the efficacy of the WHO-guidelines have major methodological
limitations: there is no randomised controlled study verifying the results of
the surveys. Therefore the guidelines have been questioned recently. The second
step of the analgesic-ladder, a non-opioid analgesic in combination with
opioids for mild to moderate pain, is discussed controversially. It has been
stated that there is no real need for this step and instead of opioids for
moderate pain such as tramadol and codeine) treatment with step-3 opioids such
as morphine and hydromorphone should be initiated as soon as step 1 proves to
be inadequate. However the three-step analgesic ladder as proposed by the WHO
is an important didactic model. This model enables physicians who are not
specialised in pain management to achieve good pain relief in their cancer pain
patients. Furthermore the published studies demonstrated high evidence of the
efficacy and safety of the guidelines. It seems to be very important to keep
these guidelines as simple as possible, so that they can be followed in every
country and remain independent of any technological environments.
Unfortunately undertreatment of cancer pain
persists in many countries. Reasons for this are the fear of addiction,
governmental regulations in prescribing opioids, inadequate opioid
availability and lack of education
of the medical staff.
In the meantime the WHO published
recommendations for the pain treatment of children with cancer as well as for
symptom relief of cancer patients in 1998. These new guidelines were published
in recognition of the different aspects in treating children suffering of
cancer and the more complex needs in palliative care.