Researchers at Johns Hopkins University have found that a popular anti-cancer drug called oxaliplatin, used to treat colorectal cancer, appears to cause nerve damage that worsens even after treatment ends, and may be permanent.
Many patients who take the drug report neurological side effects including pain in the hands and feet, numbness and tingling of the throat and difficulty swallowing.
In most cases the symptoms develop over time, but in some cases, the patient notices the effect from the moment the drug is infused.
The researchers wanted to know how the drug affects nerve cells so they recruited patients and gave them full neurological examinations to determine any nerve damage or confirm they were neurologically normal. They also had punch biopsies taken (tiny portions of skin removed from their knees and ankles). They were then given two infusions of oxaliplatin a day, over two days every fortnight (two weeks) for 12 cycles.
After this was completed, the researchers repeated the same neurological tests after 30, 90 and 180 days. At the end of the 180 days, the patients received a final checkup.
Their neurological function worsened over time. Using a microscope, the researchers saw that the nerve cells' long extensions, called axons, degenerated with use of the drug and this progressive degeneration continued even after the treatment was stopped. At the 180 day check (after the cessation of treatment), seven out of eight patient’s axons were still withering.
“This drug has rapidly become the standard of care for people with advanced colon cancer, but we really knew little about how oxaliplatin affects nerves over time,” said research leader Michael Polydefkis. “With people living longer lives on oxaliplatin, it’s important to know more about these neurological side effects so patients and their physicians can make educated choices on how this drug is used, and perhaps suggest ways to limit the damage.”
The study, published in Neurology, concluded, "This study demonstrates that oxaliplatin is associated with mild, sensory, and motor axon loss that may not be reversible. Axonal loss was detected by electrophysiology, rTNS, and distal leg IENFD. Several subjects reported prominent sensory symptoms that were not associated with axon loss, and that may or may not represent neuropathy."
The aim of the research was to bring in punch biopsies as a routine to detect neurological damage after cancer drug usage and to develop other drugs to counter these side effects.
Sources:
Popular Colorectal Cancer Drug May Cause Permanent Nerve Damage, John Hopkins Medicine, News release, 27th September 2011. http://www.hopkinsmedicine.org/news/media/releases/popular_colorectal_cancer_drug_may_cause_permanent_nerve_damage
Longitudinal assessment of oxaliplatin-induced neuropathy, Neurology, September 6, 2011 vol. 77 no. 10 980-986. Abstract: http://www.neurology.org/content/77/10/980.abstract?sid=978002a4-c22a-402c-bf60-e1e308bbd1cf
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting.
Reviewed October 18, 2011
by Michele Blacksberg RN
Edited by Jody Smith