The Rare Neurological Effects of New Cancer Treatments

Modern cancer treatments, which stimulate the immune system to attack tumor cells, have transformed the management of this disease. However, these therapies can sometimes trigger adverse reactions affecting the nervous system. A recent analysis examined data from 31 clinical trials involving more than 8,800 patients to assess the frequency of these complications.

The results show that adverse neurological effects remain exceptional, with an estimated incidence of one case per 5,000 patients treated. Among the most frequently observed disorders are peripheral nerve damage, which causes numbness or pain in the hands and feet. Next come myositis, an inflammation of the muscles, and aseptic meningitis, an inflammation of the brain’s lining without infection. Other conditions, such as autoimmune demyelinating polyneuropathy—a disease where the immune system attacks the protective sheath of nerves—as well as epilepsy and myasthenia gravis, a muscle weakness due to impaired communication between nerves and muscles, have also been reported, but with an even lower frequency.

Contrary to what one might think, the use of two simultaneous treatments rather than one does not appear to increase the risk of these side effects. Similarly, the type of cancer being treated—whether lung, liver, or skin cancer—does not influence their occurrence either. These observations suggest that these complications, although rare, may be linked to a specific immune reaction rather than the disease itself or the combination of therapies.

Neurological symptoms can be difficult to identify, as they often manifest in non-specific ways, such as headaches, muscle weakness, or sensory disturbances. Their diagnosis relies on a thorough evaluation to rule out other causes, such as disease progression or the effects of other treatments. Once confirmed, these effects are generally managed by discontinuing the treatment and administering immunosuppressive drugs, such as corticosteroids, to calm the immune reaction.

This study highlights the importance of monitoring these complications, even though their rarity reassures the overall safety of these innovative therapies. It also emphasizes the need to better understand the underlying mechanisms to improve their prevention and treatment.

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Study Citation

DOI: https://doi.org/10.1007/s00415-026-13925-8

Title: The neurological adverse events of immune check point inhibitors in the treatment of cancer

Journal: Journal of Neurology

Publisher: Springer Science and Business Media LLC

Authors: Ahmad A. Toubasi; Thuraya N. Al-Sayegh