The seroepidemiology of human-papillomavirus in relation to non-melanoma skin cancer
Non-melanoma skin cancer, comprising basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) is the most commonly diagnosed cancer in Caucasian populations. Established risk factors include exposure to solar ultra-violet radiation and immunosuppression, such as that experienced by organ transplant recipients (OTR). A role for cutaneous human papillomaviruses (HPV) in the aetiology of SCC has been suggested, but remains uncertain. The aims of this thesis were to examine the association between SCC and antibodies against the L 1 antigen of 38 HPV types using Luminex technology among Caucasian individuals and to investigate the seroepidemiology of cutaneous HPV types. Data came from a small prospective study of 39 cases and 80 controls (the Oxford component of the European Prospective Investigation into Cancer and Nutrition) and from case-control studies nested among high-risk cohorts of OTR from London and from Oxford (119 prevalent cases and 425 controls). Around 85% of controls were seroactive to at least one HPV type. In the prospective study, there were no statistically significant differences in the seroprevalence of antibodies against any of the HPV types examined between incident cases and controls. In the case-control studies, as expected, antibodies against HPV 16 were associated with a self-reported history of an abnormal cervical smear and antibodies against HPV 6 were associated with a self-reported history of genital warts, validating the methodology. However, no clear associations between any of the HPV types examined (including betaHPVs) and prevalent SCC were identified. Adjustment for potential confounding factors, such as self-reported history of sun exposure made no material difference to the results. Limitations of the studies are the low statistical power and the use of new serological assays. These serological data do not provide evidence in support of a role for HPV in the aetiology of cutaneous SCC.
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