Herpes zoster as a marker of underlying malignancy.

Herpes zoster, which presents as a painful vesicular rash occurring in a dermatomal distribution, results from reactivation of the varicella-zoster virus in the dorsal root ganglia.1,2 The rash is self-limited and resolves in 2 to 4 weeks.3 Age appears to be the key risk factor for the development of herpes zoster.4 A decrease in cell-mediated immunity is thought to be responsible for the increased incidence of varicella-zoster virus reactivation in older individuals.5 Patients with conditions resulting in impairment of cell-mediated immunity, such as lymphoma and HIV infection, and those receiving chemotherapy and steroids6 are at increased risk of herpes zoster. Although it is known that both herpes zoster and malignancy are associated with immunosuppression,7 studies examining the association between herpes zoster and a subsequent diagnosis of cancer have had discordant results.8-13 Two studies showing the presence of an association examined the risk of hematological malignancies following herpes zoster.8,9 Similarly, Buntinx et al.12 examined a database of more than 300 000 patients and found a higher incidence of cancer following a herpes zoster diagnosis among all patients over 65 years of age and among women older than 65 years of age (but not among men of this age group). However, there was no difference in incidence in the first year after diagnosis of herpes zoster, which was interpreted as indicating that the herpes zoster diagnosis was not a marker of undiagnosed malignancy. Hence, Buntinx et al.12 recommended against screening patients with herpes zoster for underlying malignancy. Conversely, 3 studies10,11,13 showed no association between herpes zoster and a subsequent diagnosis of cancer. In particular, in a recent retrospective cohort study, Wang et al.13 found that overall cancer incidence among patients with herpes zoster was no different from the expected rate in the study population. This article reports on what we believe to be the largest study to date examining whether a diagnosis of herpes zoster is a risk factor for subsequent diagnosis of cancer. More specifically, we assessed the risk of cancer following a diagnosis of herpes zoster in relation to age, sex, and type of malignancy.