A case-control study was conducted in 140 people with histology proven cutaneous squamous cell carcinoma (SCC) and 454 controls, nested within 2 cohorts of organ transplant recipients (OTR) recruited in London and Oxford between 2002 and 2006. All participants had a skin examination, completed a questionnaire and had serum tested for antibodies against the L1 antigen of 34 HPV types using Luminex technology. SCC was more common in men than women (odds ratio [OR] 5 1.7, 95% confidence interval [CI]: 1.1-2.8, p 5 0.02) and in people with susceptibility to burn easily (OR 5 3.0, 95%CI: 1.9-4.8; p < 0.001). The risk increased with increasing age (p-trend < 0.001), increasing time since transplant (p-trend < 0.001), increasing self-reported number of sunburns as a child (ptrend < 0.001) and with the presence of viral warts (p < 0.001). As expected, antibodies against HPV 16 were associated with a selfreported history of an abnormal cervical smear among women (OR 5.1, 95%CI: 2.6-10.2) and antibodies against HPV 6 were associated with a self-reported history of genital warts (OR 4.0, 95%CI: 2.2-7.2). However, no clear associations between any of the HPV types examined (including cutaneous betaHPVs) and SCC were identified. For example, the seroprevalence of HPV 5 was 15% among cases and 9% among controls (p 5 0.09) and the seroprevalence of HPV 8 was 23% among cases and 21% among controls (p 5 0.6). Nor was seropositivity to multiple types associated with SCC. These serological data do not provide evidence for a role for HPV in the aetiology of cutaneous SCC among OTR in two UK-based populations. ' 2009 UICC Key words: Epidemiology; human papillomavirus (HPV); serology; cutaneous squamous cell carcinoma (SCC); organ transplant recipients Immunosuppressed organ transplant recipients (OTR) have a higher risk of non-melanoma skin cancer than the general population. Furthermore, cutaneous squamous cell carcinomas (SCC) occur significantly more frequently than basal cell carcinomas (BCC), reversing the ratio usually found in the general population (4:1). 1,2 Ultraviolet radiation (UVR) is the main established risk factor both for SCC and BCC. 3 The strength of the association between SCC and immunosuppression, particularly after solid organ transplantation, parallels that seen for other virally associated posttransplant cancers; certain HPV types have long been proposed as potential candidates. 4 However, while the oncogenic mechanism of HPV in cancers of the uterine cervix is well-understood and the causative association is now established, it remains uncertain what role, if any, HPV plays in the aetiology of skin cancer.DNA of cutaneous HPV appears to be ubiquitous and persistent in the skin and hair follicles of healthy individuals. 5,6 Higher prevalence of cutaneous HPV-DNA has been found in the normal skin of immunosuppressed compared to immunocompetent people 7 and putative novel types are often detected. 5 Studies relying on HPV-DNA detection confront problems not only of contamination, a major consideration given t...