Chemotherapy-Induced Peripheral Neuropathy: The Invisible Side Effect

Megan McKinney-Dyson was shocked when she received a diagnosis of stage 3b colon cancer in 2021. She was just 42 years old and the mother of two young boys. After undergoing surgery and six months of chemotherapy, she is now cancer-free.

However, the treatment left her with neuropathy, which, according to the American Cancer Society, is a condition that causes pain, numbness and tingling in the hands and feet.

Although her doctor warned her that neuropathy was a potential side effect of her treatment, she wasn’t fully prepared for long-term pain and discomfort.

“Neuropathy is the biggest thing that I still have to this day,” McKinney-Dyson says. “It’s like constant pins and needles. It’s very painful.”

She tried medication, but it didn’t provide the relief she was seeking. In addition, “I didn’t like the side effects of the medicine because it made me really tired,” she says. So McKinney-Dyson turned to alternative treatments such as occupational and physical therapy.

The gap in survivorship research means that patients such as McKinney-Dyson often have difficulty getting the care they need after finishing treatment.

Read more: Peripheral Neuropathy Is 'Underestimated' in Patients Undergoing Cancer Treatment

“The growing numbers of cancer survivors are outstripping the capacity of cancer care systems to keep pace with demand,” Dr. Aisha Ahmed, an oncologist at Arizona Oncology in Tucson, says.

“Primary care physicians may not be adequately prepared to care for these survivors due to perceived knowledge gaps about the individualized needs, risks and surveillance plans for cancer survivors,” Ahmed says. This is especially true for patients who are living with long-term side effects of their treatment.

Why Neuropathy Happens

Cancer treatment often involves powerful drugs that can damage the nerves, resulting in chemotherapy-induced peripheral neuropathy (CIPN). Although any type of cancer treatment can cause neuropathy, some drugs are more likely to cause the condition.

“Certain types of chemotherapy drugs are neurotoxic,” says Dr. Kord Kober, an associate professor of physiological nursing at the University of California, San Francisco. “Unfortunately, two of the most common types of neurotoxic chemotherapies, platinum and taxane compounds, are used to treat some of the most common cancers — breast, gastrointestinal, lung, gynecologic.”

The condition can develop during treatment and persist long after treatment has ended. “Due to the lack of prospective longitudinal studies that have evaluated the onset and persistence of CIPN, we do not know the recovery rates for CIPN,” Kober says.

For McKinney-Dyson, the neuropathy affects the way she uses her hands and feet.

“For the longest time I couldn’t explain (the sensation),” she says. She describes it as “the worst feeling you’ve ever felt, for something you can’t feel,” meaning that she experiences the sensation of pain even though no physical stimuli are causing it.

McKinney-Dyson, who is an elementary school teacher, has had to adjust the way she does her job. Tying shoes, zipping jackets, buttoning clothes and even writing can be extremely painful. “I have to take more frequent breaks when I’m writing,” she says. Typing is also difficult, and she often relies on her husband’s help with many daily tasks.

CIPN is a relatively new field of study, and there is still much unknown about the condition. Kober works to increase awareness and understanding of CIPN to improve patient outcomes.

Results of a study he co-authored and is published in the Journal of Pain and Symptom Management, which focused on paclitaxel-induced peripheral neuropathy in cancer survivors, found that patients treated with paclitaxel chemotherapy had more problems with balance, the function of their upper extremities and more severe symptoms than patients who were not treated with the drug.

Results of the study also showed that those treated with paclitaxel had reduced quality of life scores in both physical and psychological domains.

Another study published in the Journal of Pain and Symptom Management found that body mass index may be a modifiable risk factor for the severity of chemotherapy-induced neuropathy. Research results show that survivors with a higher body mass index had more severe symptoms of neuropathy. This finding is significant because it suggests there may be ways to mitigate the severity of the condition with lifestyle and diet changes.

Years Later

Mark Kantrowitz, a survivor of stage 3 testicular seminoma and author of “Tumor Humor: Cancer Jokes and Anecdotes,” has CIPN, even though it has been nearly two decades since his treatment ended.

After performing a self-exam at home in 2003 at the age of 36, Kantrowitz

found a lump on his testicle. His doctor scheduled an ultrasound for two weeks later, and the results confirmed that the mass was cancerous.

Kantrowitz began treatment immediately. He underwent orchiectomy surgery to remove his testicles and three cycles of chemotherapy and was treated with a combination of bleomycin, etoposide and cisplatin. He credits his research skills for helping him understand his diagnosis and treatment options throughout the process.

Aside from his longterm CIPN, Kantrowitz experienced many rare side effects and complications, including chemo-induced pancreatitis and gallstones, high-pitch hearing loss, Raynaud’s phenomenon (decreased blood flow in the fingers) and diabetes.

The neuropathy has caused him to experience numbness and tingling in his hands and feet, as well as muscle weakness. His symptoms are very noticeable when he walks, and he uses a cane to get around.

“In my case, it mostly affected my feet, though occasionally it would affect the first three fingers on each hand,” he says.

“It’s like wearing a pair of gloves on my feet,” Kantrowitz says of the sensation. “At the same time,there is a burning and tingling sensation, sometimes really severe.” He describes the feeling as being similar to when the foot falls asleep and then begins to wake up. “Multiply that by 10 and that’s the sensation of neuropathy I experience,” he says.

According to research published by the American Society of Clinical Oncology (ASCO), the effects of CIPN can last for years. Of 986 respondents to a 2020 ASCO survey, 77% reported current symptoms of CIPN, with the average respondent being more than three years post treatment.

Learning to Cope with CIPN

McKinney-Dyson and Kantrowitz discovered ways to cope with their CIPN. McKinney-Dyson has made changes to her lifestyle and the way she completes everyday tasks. Although she didn’t do well with the medication, six weeks of occupational and physical therapy helped her gain back some of the function she’d lost.

“For patients with cancer who are experiencing CIPN following treatment, there are some prescription medications that can be used to improve symptoms. One of them is duloxetine,” Ahmed says. According to Kober, duloxetine is the only proven treatment for CIPN, but there are limited benefits to taking the medication.

Gabriela Miller, an oncology physiotherapist and owner of ACE Cancer Rehab in Mission, Kansas, works with cancer survivors before, during and after chemotherapy to help them manage treatment side effects such as neuropathy. She recommends patients with CIPN start by working with a physical therapist experienced in cancer-related side effects to help them regain function and strength as soon as possible.

“CIPN is a very real and common side effect following chemotherapy that can have a huge impact on patients’ quality of life,” Miller says. “People who experience neuropathy have decreased sensation and circulation in their feet, which puts them at risk for falling or sustaining a soft tissue injury. If the foot is injured, they run the risk of not feeling the injury, which can potentially make the wound worse.”

The effect that CIPN has on a patient’s life can be profound, with many risks and dangers that are often overlooked.

“Another danger is increased risk of falling since the balance and sensation are impaired. We also see decreased muscle strength in the muscles of the toes, which further increases fall risk,” Miller says.

Miller suggests patients with cancer consult with an oncology physical therapist as early as possible — even before treatment starts. “This way, we can detect and manage symptoms of neuropathy and educate the person on what to look for and how to improve their sensation and balance,” she says.

She emphasizes that exercises to improve circulation and sensation, as well as balance training, are important components of therapy. Learning how to manage symptoms and risks prevent falls or other injuries associated with this neuropathy.

Kantrowitz, who did not take medication for his CIPN symptoms, found that there is no one-size-fits-all solution. Although he also has issues with daily tasks such as typing, he relies on proofreading software and spelling algorithms to help him. When asked what lifestyle changes have helped alleviate his symptoms, Kantrowitz says, “Nothing really helps.”

Despite that, having a positive attitude and high pain tolerance have boosted him through some of the darkest days.

“I’ve learned that I can work through the pain,” he says. “I have a constant burning sensation in my feet 24/7.” He frequently uses distraction techniques to take his mind off the discomfort. He’s learned that his mind is a powerful tool for overcoming many obstacles, including neuropathy. “If I don’t focus on it, I can ignore it,” he says.

Kantrowitz and McKinney-Dyson both agree that the lifesaving treatment was worth the side effects.

“In my cancer joke book, “Tumor Humor,” I joke that it’s better to be alive with side effects than dead without,” Kantrowitz says. “I still would have had the same treatment. There really isn’t anything I could have done differently.”

There is much to learn about CIPN and scientists are working hard to find new ways to prevent and treat the side effect. Ahmed and Kober are hopeful that new medications and treatments will be developed to help those with this debilitating condition. Several ongoing clinical trials are testing new and advanced therapies.

“In terms of pharmacology, there are numerous clinical trials under way to evaluate for drug therapeutics to prevent and treat CIPN,” Kober says.

Scrambler therapy is one of the pain management techniques being studied. It uses electrical stimulation to “scramble” the pain signals being sent from the nerves to the brain. Although the study is still in the early phase, Ahmed is optimistic about the treatment’s potential.

“Scrambler therapy is an emerging treatment approach that appears to benefit some affected patients with CIPN,” she says. “Small studies have suggested that scrambler therapy can reduce chemotherapy-induced neuropathy symptoms, even if symptoms have been present for more than one year.”

It’s a small ray of hope and something that patients such as McKinney-Dyson and Kantrowitz can hold on to. Kantrowitz recommends other survivors speak to their doctor about any side effects they may be experiencing, even years after treatment has ended.

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