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Now, let's talk about chemotherapy-induced peripheral neuropathy.
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Chemotherapy-induced peripheral neuropathy is a type of neuropathic pain syndrome.
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Patients develop polyneuropathy that it develops after exposure to a neurotoxic chemotherapeutic agent.
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And this is a unique form of neuropathic pain.
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There is an insult, the neurotoxic chemotherapy and pain can develop after that.
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When we think about chemotherapy induced peripheral neuropathy or CIPN,
there are a few things I want you to remember.
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One is it's common. Sixty to 80% of cancer survivors
will develop a chronic neuropathic pain as a result of the chemo.
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It's seen with a number of different common medications used in the cancer center.
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Taxanes like paclitaxel, platinum agents like oxaliplatin, vinca alkaloids
like vincristine, proteasome inhibitors like bortezomib
and many others, including thalidomide. Importantly, the neuropathic pain is a dose limiting toxicity.
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So the higher dose of chemo the patients get to treat their cancer,
the more likely they are to develop neuropathy.
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And neuropathy is the most common reason to reduce the dose of the medication.
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So this is not just a bother for patients or a long-term survivorship issue.
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It's the reason cancer patients aren't treated with high doses of chemotherapy
and may have early discontinuation of treatment.
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And that can influence not only their morbidity but mortality.
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When we think about CIPN, there's a few things to consider and to remember.
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One is it's dose dependent.
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The more chemo the patient has received,
the higher the likelihood or risk for them to develop neuropathy.
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The second, it's small fiber neuropathy.
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So we see small fiber syndromes in these patients.
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Numbness is extremely common and seen in just about every patient that develops CIPN.
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Paresthesias are not uncommon and may be seen in somewhere around half of patients
that develop chemotherapy induced peripheral neuropathy.
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And frank pain is uncommon, only seen in about 20% of patients.
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So we see a lot of numbness, a little bit of paresthesias.
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And it is rare to see pain, but in those cases, can be quite severe.
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When we think about CIPN, one of the mechanisms is peripheral sensitization.
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The chemotherapy damages the dorsal root ganglion, that irritable dorsal root ganglion
is more likely to feel and be susceptible to chronic neuropathic pain.
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What are the treatments for CIPN? Well, we use a lot of the same agents for CIPN
as we do for other neuropathic pain syndromes.
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Duloxetine, nortriptyline, and many others are used.
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You can see here results of a study evaluating duloxetine versus placebo.
02:47
The placebo arm really had similar pain reported over the six weeks of the study,
whereas we see reduction in the severity of pain in the duloxetine group of patients.