Understand how side effects related to certain types of chemotherapy can affect nerves that control sensations and movements.
“Although these survivors may have beaten cancer, many of them have poor outcomes due to a number of syndromes that reduce the quality of life as a consequence of cancer treatment, including pain, which they often experience for a long time after completing their cancer treatment.”
- Glare P.A. et al doi: 10.1200/JCO.2013.52.4629.
The brain and spinal cord make up your central nervous system. The peripheral nervous system is the network of nerves outside your brain and spinal cord that sends information from your brain and spinal cord to the rest of your body. The peripheral nerves also send sensory information to the central nervous system. Every nerve in your peripheral system has a specific function, so symptoms depend on the type of nerves affected.
The peripheral nervous system is made up of three types of nerves, each with a specific function:
- Sensory nerves carry sensation, such as temperature, pain, vibration or touch, from the skin through your spinal cord to the brain. For example, a sensory nerve communicates to your brain information about objects you hold in your hand, including those related to pain, temperature, and pressure.
- Motor nerves control muscle movement and travel in the opposite direction of sensory nerves. They carry messages from your brain to your muscles. They tell your muscles how and when to contract to produce movement. For example, they tell the brain to move your leg away when you step on a sharp object.
- Autonomic nerves control body functions that are not in your direct control such as breathing, blood pressure, perspiration, heart rate, digestion, sexual arousal and bladder function. The autonomic nerves constantly monitor and respond to external stressors and internal body needs.
Thanks to advances in cancer diagnosis and therapy the number of cancer survivors is increasing but it is also true that certain side effects of treatment like chemotherapy-induced peripheral neuropathy (CIPN) are inevitable.
“Recent studies put the prevalence of CIPN at approximately 68.1% when measured in the first month after chemotherapy, 60.0% at 3 months, and 30.0% at and after 6 months.” Seretny M et al, doi: 10.1016/j.pain.2014.09.020.
CIPN is a common, debilitating, and dose dependent side effect of many chemotherapy protocols/medications. This type of neuropathy damages neurons or nerve cells disrupting the communication between neurons themselves and of neurons with the brain and spinal cord. This type of damage is called neuropathy. The effects of chemotherapy on the peripheral nervous system depends on the type of chemotherapy drug, the dose and the duration of treatment.
Neuropathy predominantly affects sensation, and/or function of the peripheral nerves.
Sensory symptoms usually develop first, involve the feet and hands and commonly present as a typical “glove and stocking” neuropathy. The usual symptoms are numbness, tingling, altered touch sensation, impaired vibration, abnormal or painful sensations caused by touch and warm or cool temperatures. These sensations can be painful and can include spontaneous burning, shooting or electric shock-like pain as well as extreme sensitivity to normal activities such as combing your hair. Motor symptoms occur less frequently than sensory symptoms and usually present as leg or foot weakness, gait and balance disturbances. These symptoms have a profound impact on quality of life and safety. For example, cancer patients who develop neuropathy are three times more likely to fall.
As data goes, the prevalence of CIPN one month after finishing chemotherapy approaches 68%, and persists in approximately a third of patients beyond 6 months. The prevalence of CIPN is dependent on the type of chemotherapy drug, with rates varying from 19% to more than 85% . About 70-95% of cancer patients report symptoms when given platinum-based chemotherapy drugs such as cisplatin, carboplatin and oxaliplatin which are commonly used as standard of care for lung, colon, ovarian and breast cancers. Taxanes are another group of common chemotherapy drugs (e.g. paclitaxel, docetaxel, abraxane) used to treat breast, ovarian and gastric cancers that cause neuropathy. Between 20-60% of patients report symptoms after taxane treatment. Other chemo drugs that can cause neuropathy include a class of drugs called plant alkaloids such as vincristine and other drugs including bortezomib. Toxicity may occur either with a high single dose or after multiple doses that are part of the treatment protocol. While some chemo drugs such as paclitaxel and oxaliplatin can cause acute symptoms during or immediately after the drug is given, generally, neuropathy symptoms usually emerge weeks or months after the completion of chemotherapy, with their severity being usually proportional to the cumulative dose of the drug. CIPN can develop, or continue to worsen, several months after treatment has stopped, in a phenomenon termed ‘coasting’.
There are predisposing risk factors for chemotherapy-induced neuropathy including patient age (higher risk in older patients), previous history of neuropathy before the start of chemotherapy (e.g., diabetic neuropathy), a history of smoking, poor kidney function and exposure to other chemotherapy agents that affect the nervous system. If you have a previous history of autoimmune diseases like lupus or rheumatoid arthritis or vascular and blood disorders, these can predispose you to chemotherapy induced neuropathy as well.
Talking to your cancer care team about the side effects of your treatment and being aware can help you deal with these side effects better. Here is a checklist that can help you recognize the common symptoms of neuropathy so you can let your cancer care team know as soon as you experience them.
Common signs and symptoms of neuropathy include:
- Tingling (‘pins and needles’) or numbness, especially in the hands and feet that may spread to the arms and legs.
- Sharp, burning, throbbing, stabbing or electric-like pain in your hands and feet.
- Feeling like you’re wearing socks or gloves when you’re not.
- Pain during activities that shouldn't cause pain, such as pain in your feet when putting weight on them or when they're under a blanket.
- Changes in sensation such as an inability to feel pain, pressure, temperature or touch.
- Painful sensitivity to touch.
- Severe pain in your hands and feet, especially at night.
- Falling, loss of coordination.
- Muscle weakness, difficulty walking or moving your arms or legs.
- Muscle twitching, cramps and/or spasms.
- Inability to move a part of the body. Loss of muscle control, loss of muscle tone or dropping things out of your hand.
- Dizziness when standing up, fainting or lightheadedness.
- Sweating too much or not enough in relation to the temperature or degree or exertion.
- Problems with urination and/or digestion including bloating, nausea, vomiting, diarrhea or constipation.
- Sexual function problems.
- Unintentional weight loss.