Invasive Techniques for Cancer Pain
General principles and management of cancer pain in adults
In approximately 10%-20% of patients with cancer pain, the response to oral and other systemic analgesics will be inadequate. Interventional pain procedures may be of value in a select group and patients should be referred to an appropriate center with the expertise to perform them. Prior to the procedure careful consideration should be given to likely benefits, risks, aftercare and possible complications, disease prognosis and expectations of the patient and family. Patients who are most likely to benefit include those with significant locally advanced disease, neuropathic pain or marked movement-related pain.9,10,67
Neuraxial drug delivery
Opioids may be delivered epidurally or intrathecally via percutaneous catheters, tunnelled catheters or implantable programmable pumps (Table 1).
Fully implanted systems offer less risk of infection and need less maintenance than percutaneous routes of administration, but their positioning is more complex. These routes of analgesic administration are associated with better analgesia, lower doses and less drug-related side effects than systemic administration, but are they not suitable in patients with infection, coagulopathy or a very short life expectancy. A trial of spinal analgesia using a temporary epidural or spinal catheter may be appropriate to help find the appropriate dose range before implanting a pump.
Because doses are much lower when opioids are administered by the spinal route, laxatives should be stopped and re-titrated. If peripheral withdrawal symptoms occur, the pre-spinal opioid should be given as necessary at a dose of approximately 25% that previously administered for breakthrough pain (i.e., prn dose).40
| Table 1: Intrathecal Infusion for Refractory Cancer Pain10 |
| 1. Life expectancy <3 months Epidural or spinal catheter (tunnelled or with implantable system) |
| 2. Life expectancy >3 months Trial of intrathecal catheter - If pain intensity decrease >50% is maintained, consider intrathecal implantable pump - If pain intensity is not reduced by 50%, remove catheter and reassess pain management |
Peripheral nerve blocks
Pain occurring in the field of one or more peripheral nerves or due to complications such as perioperative pain, pathological fracture or vascular occlusion may respond well to a peripheral nerve block or plexus block used in conjunction with systemic analgesia. Pain relief lasts for a few weeks.
Autonomic neurolytic blockade
The sympathetic nervous system carries pain afferents from the viscera. Neurolytic blockade of these afferents lasts for 3-6 months and is suitable for patients with short life expectancy. Examples of autonomic neurolytic blocks are listed in Table 2.
| Table 2: Autonomic Neurolytic Blocks/ Ablation | ||
| Block/ Ablation | Anatomy | Analgesic Applications |
| Coeliac plexus | Afferents from abdominal organs including pancreas, liver biliary tract, renal pelvis ureter, spleen, bowel to first part of transverse colon |
Pancreatic cancer, other upper gastrointestinal malignancies, including gastric cancer, oesophageal cancer, colorectal cancer, liver metastases, gallbladder cancer, cholangiocarcinoma |
| Superior hypogastric plexus |
Afferents from bladder, uterus, vagina, prostate, testes, urethra, descending colon, rectum | Pelvic pain associated with pelvic malignancy |
| Ganglion impar | Most inferior sympathetic ganglion lying anterior to sacrococcygeal junction | Advanced cancer of the pelvis and perineum, after abdominoperineal resection for rectal cancer, following radiation proctitis |