Is herpes zoster a risk factor for subsequent malignancy?

The relation between herpes zoster (shingles) and malignancy has been studied for many years. It has been well established that the herpes zoster occurs more frequently in patients with known malignancy but, whether that previous herpes zoster is associated with subsequent risk of malignancy is still controversial and so far studies have led to conflicting results. Therefore we designed this study in order to investigate a possible relationship between the previous shingles and subsequent risk of malignancies. This case-control study consisted of 268 adult patients (&ge 18 years) with diagnosis of malignancy (case group), who referred to Fatemieh hospital in Semnan, Iran. Oncology diagnosis of malignancy was based on medical history, clinical findings, and laboratory and pathology results. Adult patients without history of malignancy (n=268) were selected as control group. In both groups, age, gender and history information about shingles, type of malignancy and the interval between occurrence of shingles and cancer diagnosis were recorded in a check list. Patients with uncertain shingles history excluded from the study. The age and gender were similar in both control and case groups (p>0.05). History of herpes zoster was positive in 4.9 %(13 patients) of case group and in 10.4% (28 patients) of the control group. The difference between the positive cases in two groups was significant (OR=0.440, 95% CI: 0.22-0.86, p=0.017). The relation between shingles history and malignancy was not significant between genders. Also, the association between shingles history and malignancy in patients with 60 years of age or over was not significant, but association between shingles history and malignancy in patients less than 60 years of age was significant (OR=0.19, 95% CI:0.05- 0.67, p=0.010). Our findings showed that herpes zoster might not be a risk factor for subsequent malignancy, though in contrast, it may produce a protective effect against the occurrence of malignancy. Further studies with larger samples at the cellular and immunological levels are recommended to more clear the relation between zoster and later malignancies