One of the good effects of cancer therapies is that people can get much better or can get even healed. One of the bad effects is that some of the drugs you use have side effects. In cancer therapy usually the main side effect is sensory symptoms. Sensory symptoms are often neglected because numb pain, who cares? But it can severely inhibit your daily living activities. Just imagine you may not be able to open the buttons of your shirt or if you have these sensory problems in your legs you may have a disbalance and you may be prone to fall. So this is one side of the coin.
The other side is that people may not only have a numbness but they may also have dysesthesia, that means they feel something that isn’t there like prickling or tingling. This is also bearable but if it comes to pain then this is really disconcerting. Some of the drugs used, not all of them, can induce severe neuropathic pain.
What is neuropathic pain? Pain, as we know, is a very subjective feeling but the definition of neuropathic pain says that you have some kind of burning, shooting, electric sensations which are very unpleasant. You can imagine a little bit when the dentist touches one of your teeth you have this electric shock-like sensation but if you have this all the time this is very disconcerting.
What did you discuss today, and how is PNP linked to multiple myeloma?
Today I was given the task to speak on the symptoms of a patient. For that I went into an overview of all the drugs used for the treatment of myeloma. This is important because chemotherapy does not automatically mean that patients have neuropathic symptoms but some of them have. The drugs that really do have neuropathic symptoms are thalidomide, which is still used in many places, and also bortezomib, which is a wonderful drug but can have neuropathic symptoms up to 50%.
I tried to discuss the symptoms and signs of these patients. Also the question is the question whether a pre-existing neuropathy may matter and I mentioned that it’s not quite sure but at least for bortezomib we think that a pre-existing diabetic neuropathy may worsen. For some other drugs in chemotherapy like vincristine we know that a pre-existing hereditary neuropathy, this is a rare condition though, may have very severe effects on the development of neuropathy.
From there, this case that I have discussed was a patient who had neuropathic pain and I was asked to speak a little bit about the mechanisms of neuropathic pain. I explained that it’s usually a hyper-excitability of the peripheral nerves that also can spread to the central nervous system. It’s usually depending on what the patient says, and I say this a little bit pointed, because there is also one investigative tool that’s called nerve conduction velocity. Nerve conduction velocities can assess the neuropathy but they cannot assess what the patient feels so it does not correlate well. So it is important to listen to what the patient says. I was also able to show a very nice self-evaluation scale of the patient which has features like unbuttoning, being able to stand, feeling numbness everywhere.
From there I went to discuss the most frequently used drugs for neuropathic pain which are anticonvulsants, some types of antidepressants and also other drugs that may be upcoming. I was also asked in the discussion which to start first and my opinion was, but this is my personal opinion, that I would usually start with an anticonvulsant followed by antidepressant and I would usually not use the opioids as the first resort unless the patient is in severe pain which is unbearable. I was also making aware that increasingly there’s a tendency also for surface therapy like lidocaine patches or capsaicin patches. There may be a role also for Botox which has been tried out in diabetic neuropathy. It doesn’t have evidence yet but it may be promising because it has less side effects than drugs that have to be taken orally.
What advice can you give to patients who are suffering from PNP?
That’s a very interesting question. First of all they need to report sensory changes or worsening of senses to the oncologists because the oncologist can handle the treatment. Only the patient knows when he feels pain or he feels sensory symptoms. Then maybe the oncologist would feel the need to change a drug to avoid further toxicity. If they have this neuropathic pain then it would be good to start prescribing the drug, neurotoxic drug, but I would consult a neurologist to do that.
I was also asked a very interesting question – what about alternative therapies and what about physiotherapy and rehabilitation. My answer is that alternative therapies like acupuncture are increasingly mentioned, the evidence is lacking. However, some people profit from it, that’s fine. Physiotherapy may have a very severe role and particularly if patients have balance problems. Physiotherapy should not be confused with strengthening the muscles but it should be used to train people to balance and avoid falls. This is very important.
Thirdly I also mentioned that occupational therapy, particularly if patients have problems with their hands and fingers, become clumsy, then occupational therapy can train people to move their resources and still function better.
Any final thoughts?
One thing that is also important is that we are now fixed on the acute and chronic effects of chemotherapy induced neuropathies and we have discussed that. But what is important also is for long-term survivors we still do not know if all drug effects reverse. Increasingly in some other cancer therapies the percentage of long-term survivors is increasing so this is important and this is something to consider. I was also asked a question I did not answer in the audience, this was the question of coasting. Coasting means it comes from rollercoaster, if you know what I mean. A rollercoaster is something that takes you up a hill then you go down, you go down and you go up again and this means coasting. We are aware that in some chemotherapies, usually not in the myeloma chemotherapies but in platinum therapies, this effect happens. This means that patients who have stopped a chemotherapy even after one or two months still feel an increasing of their symptoms which is very disconcerting for the doctor and the patient but it’s something that we know and that has been observed.
Is this preventable?
No, it’s good knowledge to explain to the patient and for the patient it’s also better to know because they feel very disconcerted if it’s stopped and it gets worse. So I think it’s very good if the doctor and the patient know what’s happening.
