Chemotherapy-induced Polyneuropathy

00:01 Now, let's talk about chemotherapy-induced peripheral neuropathy.

00:04 Chemotherapy-induced peripheral neuropathy is a type of neuropathic pain syndrome.

00:10 Patients develop polyneuropathy that it develops after exposure to a neurotoxic chemotherapeutic agent.

00:18 And this is a unique form of neuropathic pain.

00:21 There is an insult, the neurotoxic chemotherapy and pain can develop after that.

00:27 When we think about chemotherapy induced peripheral neuropathy or CIPN, there are a few things I want you to remember.

00:33 One is it's common. Sixty to 80% of cancer survivors will develop a chronic neuropathic pain as a result of the chemo.

00:42 It's seen with a number of different common medications used in the cancer center.

00:47 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.

01:03 So the higher dose of chemo the patients get to treat their cancer, the more likely they are to develop neuropathy.

01:10 And neuropathy is the most common reason to reduce the dose of the medication.

01:15 So this is not just a bother for patients or a long-term survivorship issue.

01:19 It's the reason cancer patients aren't treated with high doses of chemotherapy and may have early discontinuation of treatment.

01:27 And that can influence not only their morbidity but mortality.

01:33 When we think about CIPN, there's a few things to consider and to remember.

01:36 One is it's dose dependent.

01:39 The more chemo the patient has received, the higher the likelihood or risk for them to develop neuropathy.

01:45 The second, it's small fiber neuropathy.

01:47 So we see small fiber syndromes in these patients.

01:51 Numbness is extremely common and seen in just about every patient that develops CIPN.

01:57 Paresthesias are not uncommon and may be seen in somewhere around half of patients that develop chemotherapy induced peripheral neuropathy.

02:04 And frank pain is uncommon, only seen in about 20% of patients.

02:09 So we see a lot of numbness, a little bit of paresthesias.

02:11 And it is rare to see pain, but in those cases, can be quite severe.

02:17 When we think about CIPN, one of the mechanisms is peripheral sensitization.

02:21 The chemotherapy damages the dorsal root ganglion, that irritable dorsal root ganglion is more likely to feel and be susceptible to chronic neuropathic pain.

02:31 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.

02:38 Duloxetine, nortriptyline, and many others are used.

02:42 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.