How Does Chemotherapy Cause Peripheral Neuropathy?

Chemotherapy is a powerful treatment for cancer that targets rapidly dividing cells, including cancerous ones. While it is an effective method for fighting cancer, it can also affect other rapidly dividing cells and cause side effects, one of which is peripheral neuropathy. Peripheral neuropathy is a condition affecting the peripheral nerves, which connect the brain and spinal cord to the rest of the body, including the feet, hands and organs. When these nerves are damaged, it can result in symptoms like tingling, numbness, burning pain, and muscle weakness. Understanding how chemotherapy causes this condition can help patients manage and prevent symptoms more effectively.

How Chemotherapy Affects Nerves

Chemotherapy drugs work by attacking cells that divide quickly. Cancer cells divide rapidly, so chemotherapy targets them to stop their growth.

Chemotherapy drugs can damage these nerves in several ways:

1. Oxidative Stress: Some chemotherapy drugs, like platinum-based drugs (e.g., cisplatin), cause oxidative stress. Oxidative stress occurs when the production of harmful molecules called free radicals outweighs the body’s ability to neutralize them. These free radicals can damage the protective outer layer (myelin sheath) of nerve cells and even the cells themselves, leading to peripheral neuropathy.

2. Disruption of Microtubules: Other chemotherapy agents, such as taxanes (e.g., paclitaxel), disrupt the microtubules within nerve cells. Microtubules are essential structures that help maintain the shape and function of cells. They also play a critical role in transporting nutrients and signals along the nerve cells. When chemotherapy drugs disrupt these microtubules, it impairs the nerve’s ability to function properly, leading to symptoms like numbness, tingling, and pain.

3. Inflammation and Immune Response: Chemotherapy can also trigger an inflammatory response in the body. Inflammation can lead to swelling and damage to the nerves. In addition, the immune system may mistakenly attack healthy nerve cells, contributing to peripheral neuropathy. This process can worsen symptoms and prolong recovery even after chemotherapy ends.

Risk Factors and Symptoms

Not all patients who receive chemotherapy will develop peripheral neuropathy. The risk depends on several factors, including the type and dosage of the chemotherapy drug, the patient’s pre-existing health conditions, and their genetic makeup. Some individuals may be more susceptible to nerve damage due to underlying conditions such as diabetes or previous nerve damage from other causes.

The symptoms of chemotherapy-induced peripheral neuropathy (CIPN) vary from person to person but commonly include:

- Tingling or "pins and needles" sensations, especially in the toes and feet, and sometimes the fingers and hands.

- Numbness and loss of sensation.

- Burning or shooting pain.

- Muscle weakness or difficulty with coordination.

- Increased sensitivity to temperature, particularly cold.

These symptoms can significantly affect a person’s quality of life, making it difficult to perform daily activities like walking, buttoning clothes, or holding objects.

Managing and Preventing Peripheral Neuropathy

Although CIPN can be challenging to manage, there are several strategies that patients and healthcare providers can use to reduce the severity of symptoms and improve quality of life:

1.      Dose Adjustment and Timing: Sometimes, adjusting the dose of chemotherapy or changing the treatment schedule can help minimize the risk of neuropathy. Healthcare providers may adjust the dosage to a safer level or choose a different drug that has a lower risk of causing nerve damage.

2.      Photobiomodulation with a Class 4 Therapy Laser: While relatively new to healthcare, laser therapy treatments are shown to be 90% effective at significantly reducing the symptoms associated with CIPN. The treatments are non-invasive and have virtually no side effects.

3.      Supplements and Protective Agents: Some studies suggest that certain vitamins, such as vitamin B12, or protective agents like glutathione and benfotiamine may help protect nerves and reduce the severity of neuropathy. Patients should consult their healthcare providers before taking any supplements.

4.      Lifestyle Modifications: Keeping a healthy lifestyle by managing blood sugar levels, avoiding alcohol, and engaging in regular physical activity can also play a role in preventing and managing neuropathy.

5.      Medications: Certain medications, such as pain relievers, anti-seizure drugs, or antidepressants, may help manage symptoms. These medications can help reduce pain, tingling, and other uncomfortable sensations associated with neuropathy.

Conclusion

Chemotherapy-induced peripheral neuropathy is a common side effect of cancer treatment, resulting from damage to the peripheral nerves. While chemotherapy is effective at targeting cancer cells, it can also harm nerve cells, leading to symptoms that can significantly affect a patient’s quality of life. Understanding how chemotherapy causes this condition and working closely with healthcare providers can help patients manage and potentially prevent the symptoms associated with CIPN.