Human papillomaviruses in skin cancer and cervical cancer

The causal relationship between persistent genital infections with human papillomavirus (HPV) and development of cervical cancer is well established. In contrast, the significance of infections with cutaneous HPV for development of non-melanoma skin cancer (NMSC) is not well understood. We have evaluated whether seropositivity to cutaneous HPV is a marker for cutaneous HPV infection and used high throughput HPV serology to investigate the risk for developing NMSC in relation to seropositivity for cutaneous HPV infection and PCR techniques to investigate the risk for NMSC in relation to presence of HPV DNA in the skin. We have also investigated how different sexually transmitted infections interact with HPV in the aetiology of cervical cancer. Two of our NMSC studies were hospital-based case-control studies where biopsies from skin tumours and healthy skin were analysed for presence of HPV DNA and serum samples for presence of antibodies to 14 different HPV types. The third NMSC study and the cervical cancer study were designed as prospective biobank-based case-control studies where biobanks were linked to cancer registries for identification of cancers that have occurred after donation of a serum sample. For patients with cervix cancer also formalin-fixed paraffin embedded tumour tissue was retrieved and tested for HPV DNA. In the skin cancer studies, we found that both DNA and seropositivity to HPV of genus beta species 2 associated with an increased risk for development of squamous cell carcinoma (SCC) of the skin and that sun-exposure is a risk factor for cutaneous HPV infection. In the cervical cancer study we found in addition to the exposure to the oncogenic HPV type that is found in the cancer tissue, that history of Chlamydia trachomatis stood out among the different sexually transmitted infections as being associated with increased risk for cervical cancer, suggesting that it may acts as a co-factor to HPV in cervical carcinogenesis