risk of shingles

A recent study looked at connections between cancer and the risk of shingles in a group of Australians adults.

The Varicella-zoster virus (VZV) is a member of the herpes virus family and the cause of chickenpox. Chickenpox is a contagious disease that most commonly affects children. Signs of the illness are the typical itchy blisters, which spread the virus.

Unfortunately, recovering from chickenpox as a child does not mean that we will be completely safe from this virus in the future. This virus can actually lie dormant in our nervous system for decades. If the virus reactivates, it can cause shingles.

Shingles is a painful condition that usually appears as a skin rash. In some cases, symptoms of shingles can be mild and resolve relatively quickly, while in other cases, symptoms can be more severe with extensive lesions lasting for weeks.

Risk of shingles is higher when the immune system is weaker

The reactivation of this virus is thought to be quite common, but the frequency is hard to determine because in some cases, a second infection by VZV does not cause any symptoms and goes undetected. Precisely how this virus reactivates and causes disease is also unknown, but the risk seems to be tied to a decreased efficacy of the immune system.

Cancer and its treatment, among other factors, can weaken our immune system and potentially increase the risk of developing shingles. There have been reports of shingles in cancer patients following chemotherapy, but we know little about how cancer and its treatment contribute to increasing the risk. A recent study looked at the relationship between cancer diagnosis, treatment and the risk of shingles. The results were published in the Journal of Infectious Diseases.

Blood cancers and chemotherapy increase the risk of shingles

This large-scale study involved almost a quarter-million adults from the state of New South Wales, Australia. The researchers monitored health changes (e.g. if they developed cancer or other diseases) of the participants for a period of up to nine years. They then determined the risk of shingles based on the cancer diagnosis and the type of therapy received.

The results showed that participants diagnosed with cancer had a 40% higher risk of developing shingles in comparison to those without cancer and that the risk was higher in individuals with blood cancers (e.g. leukemia) compared to those with organ cancers. People with blood cancers had a high risk of developing shingles in the two years leading to their diagnosis, with an even higher risk the following year. Prior to diagnosis, blood cancers may already affect the immune system making a viral infection more likely. The beginning of chemotherapy may have also further increased a patient’s risk of developing shingles.

A limitation of the study is that scientists could not isolate the extent to which chemotherapy increased the risk of shingles in patients with blood cancers because nearly all of them received this type of treatment. Therefore, a comparison with a group of people that did not undergo chemotherapy was not possible. In participants with organ cancers, on the other hand, researchers were able to determine that chemotherapy led to an increased risk of shingles compared to those that did not receive this treatment.

Understanding the risk factors for shingles can help build prevention strategies

This study evaluated the risk of shingles in a large group of people over a long time period and discovered that patients with blood cancers, as well as those with organ cancers who undergo chemotherapy have an increased risk of developing this disease. Patients with cancer and those receiving chemotherapy not only have higher chances of developing shingles but also are more likely to suffer from complications.

The use of preventive antivirals in patients with blood cancers receiving chemotherapy is recommended, but guidelines are not as clear when it comes to organ cancers. A new shingles vaccine was recently developed and was proved safe for use in individuals with compromised immune systems, potentially providing a powerful resource for the prevention of this disease in cancer patients. The study discussed here provides important information that can be used to help build the foundation to justify future prevention strategies.

Written by Raffaele Camasta, PhD

References

  1. Qian, J., Heywood, A. E., Karki, S., Banks, E., Macartney, K., Chantrill, L., & Liu, B. (2018). Risk of Herpes Zoster Prior to and Following Cancer Diagnosis and Treatment: A Population-Based Prospective Cohort Study. The Journal of Infectious Diseases.
  2. Yawn, B. P., & Gilden, D. (2013). The global epidemiology of herpes zoster. Neurology, 81(10), 928–930.
  3. Kennedy, P. G. E., & Gershon, A. A. (2018). Clinical Features of Varicella-Zoster Virus Infection. Viruses, 10(11), 609.
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