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Highlights of Attempts at Prevention and Treatment of Chemo-Induced Peripheral Neuropathy
Chemotherapy is a common contributor to peripheral neuropathy, and because of this, there have been efforts to both prevent and treat chemo-induced peripheral neuropathy (CIPN). However, much of the work in this field has been hampered by difficulty in measuring this, as well as trials that are pretty small.
A couple have been the subject of trials that were negative, showing no benefit for the investigational agent, including the radioprotectant amifostine, the calcium channel blocker nimodipine, and some others.
A few have had some mixed and some positive results. Among these, vitamin E has been suggested in trials to reduce the frequency and severity of CIPN, but as an anti-oxidant, there is some concern that it may compromise the effectiveness of chemotherapy. Others that have looked favorable in small studies have included glutamine, glutathione, N-acetylcysteine, and calcium and magnesium infusions, though the last have raised some questions about being associated with reducing the efficacy of chemotherapy. Overall, with most of these being such small trials, and without establishing that prevention of neuropathy occurs without a compromise of the effectiveness of the chemotherapy, none of these has become a standard treatment. In the meantime, there are ongoing trials looking at whether certain approaches prevent CIPN, including acetyl-L-carnitine, vitamins B6 and B12, and alpha lipoic acid.
Chemotherapy-Induced Peripheral Neuropathy
Peripheral neuropathy is a common complication of multiple widely used chemotherapy agents, and this symptom often limits our ability to have patients continue on the same treatment, even when it’s effectively treating the cancer. Typically, the symptoms are more sensory than motor, and the leading complaints are numbness and tingling, cold sensitivity, sometimes burning, electric, and sometimes normal pressure is perceived as painful. Diminished proprioception, the perception of a person’s body in space, can lead to balance problems and falls. And while dysfunction of autonomic nerves, which mediate the body’s automated body processes like temperature regulation, blood pressure and heart rate bowel fucntion, etc., is felt to be rare, this hasn’t been well studied. It’s possible that issues like difficulty regulating blood pressure, constipation, and urinary difficulties may in fact be related to neuropathy of autonomic nerve function.
The classical side effect of chemo-inducted peripheral neuropathy is sensory and symmetric, affecting both sides of the body relatively similarly, unlike nerve compression, which affects a single nerve and is not symmetric. Because neuropathy preferentially affects the longest nerves of the body first, and these are the nerves that run from the spinal cord to the tips of the feet and hands, a neuropathy in a stocking-glove distribution is what is typically seen.
Neuropathy in Cancer: That Tingling Feeling That Isn’t Love
Neuropathy, also known as peripheral neuropathy, is a common medical problem caused by damage and dysfunction to one or more peripheral nerves, which are the nerves connecting the brain and spinal cord to the rest of the body. There are three different types of nerves: sensory, motor, and autonomic (controlling reflexive/automatic body processes like blood pressure, heart rate, temperature regulation, sweating, etc.).
It is a very common problem, seen in about 3-4% of people, and it’s particularly common in people over 55. About one third of cases are due to diabetes, and another third are termed idiopathic, a fancy sounding term just meaning that we can’t determine that cause of the problem (though a medical school professor of mine uncharitably suggested that it came from the idea that your doctor is an idiot, and that’s pathetic). The remaining third are from a range of identified causes such as chemotherapy or other medications, autoimmune diseases, infections, nutritional deficiencies, metabolic disorders, or genetic-mediated nerve damage.
Cancer Pain 101
In reviewing posts from GRACE, it’s not surprising to see that pain is major issue for many patients with cancer. Pain is not unique to cancer, but for most patients with cancer, their pain is related to the cancer in some way. In cancer, the causes of pain not only include the disease itself, but also the treatments and procedures involved. There are particular types of pain and pain syndromes that are seen primarily in patients with cancer compared to other illnesses. Within oncology and pain management, cancer pain is so crucial for patient care that it has become essentially its own specialty in recent years. Dr. Janet Abrahm, an oncologist and cancer pain expert at the Dana Farber, has written one of the definitive texts on cancer pain management which is a major reference for this post.
Cancer-related pain can be categorized in several ways into what time course it follows. Patients who have acute cancer-related pain have pain that is expected to improve with cancer-directed therapy or, if it is a treatment-related complication, will resolve after treatment. Chronic cancer-related pain is not expected to resolve or its source cannot be eradicated. This chronic pain is very frustrating; similar to non-cancer patients with chronic pain, treatment focuses on therapies that can help patients function and improve their quality of life.
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