Shingles, a painful rash caused by the reactivation of the chickenpox virus, and cancer share a connection rooted in the body’s immune system. When the immune system is weakened, the risk for shingles increases. For individuals with cancer, this link is an important part of managing their health, as the disease or its treatments can increase the likelihood of developing shingles.
The Immune System Connection
The virus responsible for both chickenpox and shingles is the varicella-zoster virus (VZV). After a person recovers from chickenpox, VZV enters a dormant state within nerve cells near the spinal cord and brain. For decades, the virus can remain inactive, held in check by a healthy immune system.
The immune system’s ability to suppress VZV relies on a specific type of white blood cell known as a T-cell. These cells are trained to recognize and control pathogens like VZV. This cellular immunity effectively keeps the virus confined to its latent state, preventing it from multiplying.
When the immune system is weakened (a state known as immunosuppression), its ability to control VZV diminishes. With fewer or less effective T-cells, the dormant varicella-zoster virus can reactivate. It then travels along a nerve pathway to the skin’s surface, causing the painful, blistering rash of shingles.
Why Cancer Patients Are at Higher Risk for Shingles
The link between cancer and an increased risk for shingles is grounded in immunosuppression. People with cancer have a reported 40% higher risk of developing shingles compared to those without cancer. This vulnerability arises from both the disease itself and the treatments used to fight it.
Certain types of cancer, particularly hematologic or blood-related cancers, directly compromise the immune system. Malignancies like leukemia and lymphoma originate in the cells of the immune system, disrupting their normal function. This means the immune system is less capable of keeping the dormant varicella-zoster virus in check, creating a higher risk for shingles even before treatment begins.
The therapies used to combat cancer are a major factor in increasing shingles risk. Chemotherapy targets and destroys rapidly dividing cells, but this process does not distinguish between cancer cells and healthy immune cells. Radiation therapy can also suppress the immune system, particularly when directed at large areas of bone marrow where immune cells are produced. Immune-suppressing drugs like corticosteroids, often used in cancer treatment, further diminish the body’s ability to fight off viral reactivation.
Does Shingles Signal an Underlying Cancer?
While cancer increases the risk of shingles, the reverse association is also notable. A shingles outbreak does not cause cancer; however, it can be an early indicator of a weakened immune system from an undiagnosed malignancy. The onset of shingles, particularly in younger individuals without another clear cause for immunosuppression, may prompt a closer look at a person’s underlying health.
Studies have shown that individuals have a higher likelihood of being diagnosed with cancer, especially hematologic cancers like lymphoma and leukemia, within two years following a shingles episode. This suggests that a developing cancer may have already started to weaken the immune system. This allows the varicella-zoster virus to reactivate before the cancer itself has been detected.
This connection is a statistical probability, not a certainty for every person who develops shingles. The vast majority of shingles cases are not linked to an underlying cancer. However, the association is strong enough that the appearance of shingles can be a reason to discuss any potential underlying causes of immune weakness with a healthcare provider.
Preventing and Managing Shingles During Cancer Care
Given the heightened risk, preventing and managing shingles is an important aspect of cancer care. Proactive measures can help protect vulnerable patients from the painful rash and its potential complications.
Prevention is centered on vaccination. The recommended vaccine, Shingrix, is a recombinant zoster vaccine, meaning it does not contain a live virus and is safe for many cancer patients. It is administered in two doses and has shown high effectiveness. The timing of vaccination is often planned around cancer treatment cycles to coincide with periods when the immune system is stronger.
For a cancer patient who develops shingles symptoms, such as a localized tingling or rash, seeking immediate medical attention is necessary. Prompt treatment with antiviral medications can reduce the severity of the illness and shorten its duration. This is important for preventing complications like postherpetic neuralgia (PHN), a condition of persistent nerve pain that can last for months or years after the rash has healed.