One of the important problems in cancer patients is the complaint of pain. Pain is present in 30% of newly diagnosed patients and in more than 70% of patients with advanced cancer.
PAIN TYPES
Three types of pain have been described:
Somatic pain
It occurs with the activation of nociceptors in the cutaneous or deep tissues. It is a well-localized pain. Metastatic bone pain, pain at the incision site after surgery, myofascial and musculoscletal pain are included in this group.
Visceral pain
It results from the activation of nociceptors by infiltration, compression and stretching of the thoracic, abdominal, and pelvic organs. It typically occurs in patients with intraperitoneal metastases and is common in pancreatic cancer. It is not well localized, it is defined as a feeling of pressure, compression. When acute, it is accompanied by autonomic dysfunction such as nausea and vomiting.
Neuropathic pain
It occurs as a result of damage to the peripheral or central nervous system due to reasons such as compression and infiltration. Again, iatrogenic can be seen as a complication of radiotherapy, chemotherapy and surgical treatments.
These three types of pain may occur singly or in combination in the same patient. Different drug and non-drug approaches may be necessary in these pain types.
PAIN OVER TIME
Acute pain
It is usually well-defined onset and often accompanied by symptoms of autonomic nervous system dysfunction.
Chronic pain
is pain that persists for more than 3 months. The beginning is not well remembered. It is usually adapted to pain and accompanied by behavioral and lifestyle changes.
CLINICAL ASSESSMENT OF PAIN
Careful history
Evaluation of the patient’s psychological state
Detailed systemic and neurological examination
Diagnostic scans
Providing analgesia
Regular evaluation of response to treatment
Individualization of diagnostic and therapeutic interventions at the patient level
Defining the exact target in treatment
Patients and their relatives information
PAIN MANAGEMENT
Pain management is multidisciplinary and is carried out together with the treatment of the patient’s primary disease. In addition to analgesic drug therapy, anesthetic and surgical measures should be taken when necessary, and rehabilitation and psychiatric treatment should be applied.
Pain is controlled by drugs with certain regulations. More preferred is the WHO regulated step therapy. Basically, in this method, treatment with NSAIDs is started and treatment is continued in a process leading to opioid use, depending on whether the pain is controlled or not.
Step 1 pain management
Mild to moderate cancer pain is treated in this step. This group of patients should be treated with nonopioid analgesics. An adjuvant can be added according to the specificity of the pain.
2nd step pain treatment
In this group, mild or moderate uncontrolled pain is treated in primary care. An opioid is added to the nonopioid analgesic (codeine, oxycodone). If necessary, an adjuvant should be added according to the pain characteristic.
Third-line pain treatment
Pain that cannot be controlled by second-line pain treatment falls into this group. A nonopioid is combined with an opioid (morphine). Adjuvant should be added in necessary cases.
Drugs used as adjuvant are often Amitriptyline, carbamazepine, Corticosteroids.
Pain can be controlled in 90% of patients with pain medication with a careful approach. Less than 10% may require more invasive methods.
Morphine
It is the most important component of pain treatment. Generally, in the treatment of cancer pain, the dose can be increased until pain control is achieved.
Pharmacokinetics
When taken orally, it is eliminated in the liver in the first pass. Therefore, care should be taken when adjusting oral and parenteral doses.
In intravenous use, the effect is maximal in 10-20 minutes and disappears in a short time. The half-life is 2-3 hours.
In intramuscular or subcutaneous application, the effect starts in 2 minutes and reaches a maximum in 45-9 minutes. The effect lasts for 4-6 hours.
Mechanism of action: Morphine affects pain pathways at both spinal and supraspinal levels. At the spinal level, it causes presynaptic inhibition by activating presynaptic opioid (delta and kappa) receptors in the posterior horn of the spinal cord. It performs supraspinal analgesia via mu receptors.
Effects of morphine:
üAnalgesia
üSedation
üRespiratory depression*
üNausea and vomiting
ü
üHypotension
üHypothermia
üAntitussive effect
üImproves stomach tone, delays its emptying, increases acid secretion
üConstipation
ü Spasm in the bile ducts and oddi sphincter
üIncreases bladder tone, urinary retention
üReduces salivary glands secretion, dry mouth
üTolerance and addiction**
* Respiration In the case of depression, the antidote is naloxane.
** Addiction may be seen at very low rates in the treatment of pain in cancer; therefore, it is not a criterion in the planning of treatment.
