What causes pain in pancreatic cancer?
One of the common presenting complaints of cancer is pain. Often pain is the reason behind a series of investigations culminating in the eventual diagnosis. Nearly 75% of pancreatic cancer patients suffer from pain at the time of diagnosis and these increases to over 90% in advanced stages.
The pain may be moderate to severe with adverse effect on quality of life, functional ability and mood. Most patients complain of intermittent or constant, deep pain in the upper part of tummy just below the ribcage. It may be squeezing, cramping, sharp, burning or aching in character. Pain is often more on the left and can spread towards the back. It is often aggravated by oral intake of fluids or solids.
Pain management in pancreatic cancer can be challenging because of the aggressive nature of the disease. There is evidence supporting earlier treatment of pain, so it’s better to seek help early.
Pain in cancer may be related to
- Increased pressure or the blockage of pancreatic ducts
- Inflammation of the pancreas /nearby areas
- Pressure/ spread to the neighbouring structures such as
- Nerves (in approximately 70–90% of cases)
- Blockage of the duodenum (the first part of the small intestine) impeding the flow of food
- Bowel or peritoneum (inner covering of the tummy)
- Bone (not very common)
- Other associated problems such as constipation and digestion issues
- Distension of abdomen due to increased fluid (ascites)
- Irritation of diaphragm leading to the shoulder pain
- Side effect of treatments such as chemotherapy, radiotherapy, surgery (as in peripheral neuropathy (nerve damage) /enteritis)
- An unrelated coincidental problem such as arthritis of joints of the spine
What are Splanchnic nerves and Coeliac plexus?
Coeliac plexus is a network of nerves located in upper part of tummy (abdomen) just behind the pancreas. It lies deep in the tummy in front of spine and around a big blood vessel called aorta. This network of nerves plays an important role in sending messages from the upper abdominal organs to the brain.
Splanchnic nerves are a group of nerves located on both sides of the spine. They are closely related to the Coeliac ganglion and carry pain information from organs in your abdomen to the brain.
What kinds of procedures are performed to reduce pain in pancreatic cancer and how can they help?
The below mentioned procedures are utilised not only for pancreatic cancer but also for other upper abdominal cancers such as those of liver, gall bladder, stomach, some parts of intestine. These can also help in some non-cancer pains such as in chronic pancreatitis.
These procedures may not be a permanent cure for the pain but have the potential to offer significant & lasting relief. Nerve blocks work well for some people, but they don’t work for everyone and may take some time to show the full effects.
These procedures can be classified as
- Diagnostic blocks– Blocking the coeliac plexus of the splanchnic nerves involves injecting local anaesthetic with or without steroids around these nerves to interrupt the pain signals being sent to the brain. This can reduce the pain one perceives and help in predicting if other procedures such as neurolysis will work or not.
- Neurolytic blocks– these procedures involve use of chemicals such as alcohol / phenol to achieve prolonged interruption of pain signals being transmitted by nerves.
- Radiofrequency procedures for splanchnic nerves– these procedures utilise radiofrequency energy to heat the needle tip which in turn reduces the pain signals being transmitted to the brain.
Which intervention and approach is most suitable for a patient will depend on individual factors such as the extent of disease, concomitant problems such as breathing issues or ascites, ability to lie on the tummy/ back etc. Sometimes multidisciplinary review is required (such as reviewing the scans with radiologists) for deciding on the most suitable option.
Depending on the approach chosen the procedure may require for the patient to lie on their back or tummy for a period of approximately 45 min to an hour. A guiding modality is used to accurately place the needles close to the target nerves. This may include
- X Ray (Fluoroscopy) guidance
- Ultrasound guidance
- CT guidance
- Endoscopic guidance
- OR a combination of above mentioned modalities
Once the needles are in the correct place a dye may be used to assess how the medications would spread and to confirm the accurate placement of needles. An attempt is then made to reduce the pain signals being transmitted by these nerves via radiofrequency or drugs.
How much pain relief can be expected after the procedure and for how long will it last for?
The pain relief after the injection can vary depending on the cause of pain, location and extent of disease. In some studies it has been observed that the outcomes are better if the block is performed soon after the onset of pain asin advanced disease large tumours can act as mechanical barrier preventing the spread of the drugs hence achieving only partial relief.
These procedures have the potential of reducing the pain and the medication requirement for medium term. Overall, 70%–80% of patients undergoing these procedures report decreased pain for 1–6 months.
What are the risks of having these procedures?
No intervention is risk free. The decision to perform or not perform an intervention is taken by evaluating the risk/benefit ratio. The risks will vary depending on the intervention chosen and the patient’s medical issues. When performing these procedures, precautions are taken to reduce the risks as much as possible such as performing the procedure under guidance (x-ray, ultrasound, CT etc), use of contrast (dye) to assess the spread of medications and use of electrical stimulation in radiofrequency procedures etc.
Common side effects of these procedures include local pain (96%), lowering of blood pressure (10%) and loose stools (44%). Fortunately most of the common side effects are short lasting.
Some of the risks can be serious. Studies have reported the risk of serious adverse events as approximately 2%. It is best to discuss these with your treating doctor as the list of these can be long and vary with the intervention chosen.
What else can be done to reduce the pain?
Different types of pain killers can be used based on the type of pain and other medical problems. Often the painkillers dose needs to be changed or new ones need to be added as the disease changes.
Morphine and Morphine like drugs (collectively known as Opioids) are one of the strongest pain killers. Other drugs in this class include fentanyl and oxycodone. These painkillers can be given by different routes lincluding orally, intravenously (directly into the veins), subcutaneously (below the skin) or as patches. Oral medications also come in a slow release form which provide more consistent pain relieve throughout the day. These drugs have often been in the limelight due to the wrong reasons such as addiction/ abuse potential and hence the social taboos associated with their use. Patients often do a disservice to themselves by harbouring preconceived notions and putting up barriers. It is important that you openly discuss any such issues with your Pain Specialist.
Other types of pain may require different class of pain killers such as anti-inflammatories for pain due to inflammation, neuropathic medications such as gabapentin and pregabalin for nerve type of pain etc.
As with any other medication there are side effects associated with all these medications and these can be dealt with in most cases by patient education, pre-emptive action, use of medications and lifestyle modification.
Pain control in cancer is not just about medications or injections… there is more to it. To achieve a satisfactory control it often requires addressing the concomitant factors which can serve to enhance the pain experienced. For example
- Relationship between one’s emotional state such as low mood /anxiety and pain is well known. These factors can magnify the perceived pain and hence addressing them is important. Relaxation therapies such as meditation, mindfulness may help in managing thoughts, coping with feelings and produce a calming effect.
- Abdominal and back pain worsen with coexisting problems like constipation and abdominal distension and hence the importance of addressing these.
Refractory end of life pain can be dealt by delivering pain killers directly into the spine by using intrathecal/ epidural route.