April 4, 2013 | by Shawn Le
Cancer patients treated with chemotherapy often experience side effects from the toxic compounds – the most common effects being nausea, vomiting and fatigue. Further, about 20 to 40 percent of patients who receive a category of chemotherapies known as neurotoxins can experience a painful condition known as chemotherapy-induced peripheral neuropathy.
This condition, caused by chemotherapy-induced nerve damage, can last months to years after chemotherapy treatment. Now, researchers from a national collaboration of hospitals and cancer centers have found that the antidepressant duloxetine – sold under the name Cymbalta – can ease such pain if given during the first five weeks of treatment. Their findings were published online Wednesday in The Journal of the American Medical Association.
Duloxetine is already approved for use in treating diabetes-induced peripheral neuropathy. Researchers hypothesized that the drug could have a similar effect on chemotherapy-induced peripheral neuropathy. The study authors reported: “Among patients with painful chemotherapy-induced peripheral neuropathy, the use of duloxetine compared with placebo for 5 weeks resulted in greater reduction in pain.”
That’s good news to Carin van Zyl, M.D., a palliative and pain specialist in City of Hope’s Department of Supportive Care, who commented on the study in an interview with MedPage Today. “Nerve damage from chemotherapy agents is a really huge problem in cancer treatment,” she said in an accompanying video interview. “And for many years, although there were things that we could try, no one has really identified a drug that works very well to control this kind of pain.”
The study enrolled 231 patients who were 25 years or older and received chemotherapy treatment between April 2008 and March 2011. Of this group, 115 patients received one week of daily duloxetine followed by four weeks of a daily placebo pill, and 116 patients received one week of a daily placebo pill followed by four weeks of daily duloxetine. Eleven patients in this group ended up not receiving treatment, leaving a total of 220 treated patients in the analysis.
Van Zyl is cautious about results, though. She said the study “didn’t look at treatment effect beyond five weeks. In the pain management world, where people can have these kinds of issues with pain for many months, or even years – and for a few unlucky patients, even a lifetime – we don’t know whether the effect that is seen in five weeks is going to last beyond that period of time.”
Researchers asked patients to assess their pain level with a 10-point scale that is commonly used in palliative care – with zero representing no pain and 10 representing as bad as can be imagined. On average, patients who received four weeks of duloxetine reported a roughly 1-point decrease in their pain level during treatment compared to patients who received a placebo. And 59 percent of those receiving duloxetine reported some amount of decreased pain versus 38 percent of those receiving a placebo.
Overall, for van Zyl, duloxetine will be another treatment option used in combination with other drugs. “Although [the reported pain reduction] was definitely more than placebo … it wasn’t the kind of thing that made the pain vanish. So, it still looks pretty clear that we’re going to use a combination of drugs to help patients with this kind of pain.”
The researchers themselves note that patients and physicians should weigh the side effects of duloxetine itself, as well as possible drug interactions, in deciding whether to follow this course of treatment. They also report that duloxetine may show different results depending on the type of chemotherapy patients receive.
However, they write: “In conclusion, 5 weeks of duloxetine treatment was associated with a statistically and clinically significant improvement in pain compared with placebo.”