Chemotherapy-induced peripheral neuropathy (CIPN) is a common long-term problem in people who have been treated for cancer. Symptoms of this type of nerve damage can include pain, numbness, weakness, and tingling, especially in the hands and feet. The condition can greatly impair someone’s daily life, affecting sleep, mobility, balance, and the ability to perform tasks that require fine motor control, like buttoning shirts and tying shoes.
At the recent San Antonio Breast Cancer Symposium, a team of Memorial Sloan Kettering experts led by medical oncologist and integrative medicine specialist Ting Bao presented updates on two studies that focused on different aspects of CIPN in breast cancer survivors.
“CIPN is a major problem, especially with the growing number of cancer survivors,” Dr. Bao says. “There are currently few good treatments for CIPN, and there are lots of areas that need to be investigated. That’s what I’m trying to do with my research.”
Chemotherapy’s Double-Edged Sword
CIPN is especially widespread in people who have received chemotherapy for breast cancer, colon cancer, or rectal cancer. In the case of breast cancer, the culprit is a class of chemotherapy drugs called taxanes. This group includes paclitaxel (Taxol®) and docetaxel (Taxotere®). For colorectal cancer, it’s a different class, called platinum drugs, like oxaliplatin (Eloxatin®).
Investigators are still learning why particular drugs cause nerve damage. They believe it’s a combination of several reasons. One issue is that these drugs interrupt the function of microtubules, the tiny filaments inside cells that provide support and help with cellular transport. They may also disrupt mitochondria, which provide cells with the energy they need to grow and divide.
In cancer cells, inducing this type of damage is what makes chemotherapy effective. It makes the cancer stop growing and die. But when the injury happens to nerve cells instead, consequences can be detrimental.
Some clinical trials have looked at the effects of various pain medications on CIPN, including duloxetine (Cymbalta®) and gabapentin (Neurontin®), but the results have been somewhat disappointing, Dr. Bao says. She notes that some people take these drugs anyway because they are looking for any type of relief.
“People try all kinds of things, like soaking their feet in warm water and rolling them on marbles to try to restore some of the feeling. This technique can be very helpful for some,” she adds.
Looking to Integrative Medicine
Dr. Bao and her colleagues on the Breast Medicine and Integrative Medicine Services are looking beyond drugs to find new ways to relieve CIPN. One of the studies she discussed in San Antonio was a small randomized, controlled study that looked at the potential benefits of yoga in survivors of breast and gynecologic cancers who have CIPN. The trial, which is still ongoing, is designed to evaluate whether yoga can improve balance and prevent falls in people with moderate to severe nerve damage, which doubles the risk of fall.
Dr. Bao is also studying whether acupuncture can prevent CIPN from worsening in people being treated with paclitaxel. She recently completed a small three-arm study and is waiting for the results to be analyzed.
Quantifying Improvement in CIPN
Another study presented by Dr. Bao in San Antonio focused on gauging CIPN’s effects. In addition to patient questionnaires, Dr. Bao’s team measured the degree of CIPN by testing the sensitivity of fingers and toes to touch and vibration, among other factors.
“As we begin to look at new ways to treat CIPN, it’s important to measure whether the interventions are effective and to have better tools to study why and how certain treatments work,” Dr. Bao says. “Historically, it’s been difficult to get funding to support trials that focus on quality of life after treatment, because of the lack of objective ways to measure improvements. We hope that once we have better tools to determine what works and what doesn’t, it will boost interest in our work.”