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1. Herpes zoster was not found to be a risk factor for subsequent cancer, though there were significantly higher incidences of melanomas and bone/soft-tissue malignancies
2. There is insufficient evidence to warrant investigating for occult malignancy or closer surveillance for new onset cancer in individuals with herpes zoster
Primer: Herpes zoster is a viral illness (often referred to as shingles) that presents with painful, bullous skin rash often along a dermatome. It is caused by reactivation of the varicella zoster virus, and is commonly seen in immunocompromised individuals. There is limited and conflicting evidence exploring the link between herpes zoster and the risk of developing subsequent cancer, with some studies suggesting herpes zoster is a risk factor for developing malignancy and others suggesting the opposite is true. Furthermore, much of the existing evidence explores the association in western countries, and this may be of limited applicability to Asian populations.
For further reading regarding the link between herpes zoster and developing malignancy, please see the following studies:
This [retrospective cohort] study: Published recently in CMAJ, a population-based, retrospective cohort study sought to explore whether there was increased incidence of cancer after herpes zoster in the Taiwanese population. The final analysis involved 35,871 patients with newly diagnosed herpes zoster, and 895 cases of cancer were subsequently identified. There was no increased risk of cancer compared with the general population, though there was increased risk of certain malignancies, including melanoma (standardized incidence ratio 2.03; 95% CI 1.01-3.63) and bone/soft-tissue cancers (2.03; 95% CI 1.11-3.41).
In sum: This study demonstrated that there was no increased risk of cancer amongst patients subsequent to herpes zoster. There were higher incidences of melanoma and bone/soft-tissue malignancies after episodes of herpes zoster. This study contrasts with 2 recent publications suggesting that herpes zoster is a risk factor for developing malignancy, though these differences may be due to differences in the ethnicity of the study populations.
The strength of this study is that it was conducted using a large national, population-based registry of data. The study suffers from limitations often encountered in observational studies, including the fact that follow-up was limited to 9 years, while longer follow-up may be necessary to detect newly onset malignancies.
While the evidence regarding herpes zoster as a risk factor for subsequent malignancy is still quite limited, there is no strong evidence to support closer surveillance for cancer after episodes of shingles. Moreover, there is insufficient evidence to warrant screening for occult malignancy in patients who develop herpes zoster.