Acta Dermato-Venereologica 99-13CompleteContent

1275 INVESTIGATIVE REPORT Increased Risk of Cutaneous Squamous Cell Carcinoma in Organ Transplant Recipients and Patients on Chronic Dialysis: A Cancer Registry-based Study in Taiwan Chao-Hsiun TANG 1# , Yuh-Mou SUE 2,3# , Wen-Ting HSIEH 1 , Ya-Hui WANG 4 and Chia-Chen WANG 5,6 1 School of Health Care Administration, College of Management, Taipei Medical University, 2 Division of Nephrology, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, 3 Division of Nephrology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, 4 Department of Medical Research, Cardinal Tien Hospital, 5 Department of Dermatology, Cardinal Tien Hospital, and 6 School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan # These authors contributed equally and should be considered as first authors. This study investigated the predominant skin cancer subtype among organ transplant recipients, patients on chronic dialysis, and patients with chronic kidney disease in Asian subjects. Among 23,644 patients with skin cancer, identified from Taiwan Cancer Registry Da tabase, 53 were organ transplant recipients, 255 were on chronic dialysis, 1,792 had chronic kidney disease, and 21,544 were in the control group. The propor tions of squamous cell carcinoma were 52.8%, 47.8%, 40.1%, and 33.5%, respectively. Compared with the control group, organ transplant recipients (1.99-fold) and patients on chronic dialysis (1.25-fold) were at higher risk of developing squamous cell carcinoma than other skin cancers after adjustment for potential confounders. Subgroups or covariates associated with increased squamous cell carcinoma compared with other skin cancer risk included patients with chronic kidney disease aged < 70 years (vs. control group; 1.3- fold), old age (vs. young age; 2.8-fold), male sex (vs. female sex; 1.1-fold), and south Taiwan residency (vs. north Taiwan residency; 1.1-fold). Organ transplant recipients and patients on chronic dialysis had immune dysregulation, resulting in increased risk of squamous cell carcinomas. Key words: organ transplant recipient; dialysis; chronic kidney disease; squamous cell carcinoma; epidemiology. Accepted Oct 15, 2019; E-published Oct 17, 2019 Acta Derm Venereol 2019; 99: 1275–1281. Corr: Chia-Chen Wang, Department of Dermatology, Cardinal Tien Hospi- tal, and School of Medicine, Fu-Jen Catholic University, No. 362, Zhongz- heng Rd, Xindian Dist., New Taipei City 231, Taiwan. E-mail: jamiewang@ tma.tw S kin cancer is the most common cancer in Caucasians. Non-melanoma skin cancer (NMSC) accounts for the vast majority of skin cancers, and basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common subtypes. The BCC to SCC ratio in the general population is 4:1 in the UK and 5:2 in Australia (1). The risk of NMSC increases with exposure to ultraviolet radiation, fair skin pigmentation, older age, and among people with certain medical conditions affecting the immune system. A greater increase in risk of SCC than SIGNIFICANCE Organ transplant recipients, patients on chronic dialysis, and patients with chronic kidney disease have immune dys- regulation and are at higher risk of skin cancers. However, the predominant skin cancer subtype in these populations has not been well-investigated among Asian subjects. The study revealed that organ transplant recipients, patients on chronic dialysis, older patients, males, and residents of south Taiwan (which has a high level of solar radiation) had a higher risk of developing squamous cell carcinoma than other skin cancer subtypes. The study provides aetiological insights into the development of squamous cell carcinoma and highlights that physicians should be aware of the in- creased risk of squamous cell carcinoma in these conditions. BCC is observed in many immune-related conditions (2). Most notably, with the requirement for long-term immunosuppressant treatment to avoid graft rejection, organ transplant recipients (OTRs) of Caucasian ethnicity are at 65- to 250-fold and 10- to 16-fold risk of SCC and BCC, respectively, compared with the general popula- tion (3–5). The risk of SCC in OTRs is greatly increased compared with the risk of BCC, with a SCC to BCC ratio of 1.6:1 in the Netherlands (5) and 1:1 in Denmark (6). Compared with OTRs of Caucasian ethnicity, there is a much lower incidence of skin cancers among OTRs of Asian ethnicity. Among studies regarding the risk of cancer in OTRs from Japan (7, 8), Korea (9), China (10), Taiwan (11, 12) and Asian immigrations to the USA (13), the number of cases of skin cancers was quite small, and the proportion of histological subtypes was unclear. Patients on chronic dialysis (14, 15) and those with pre- dialysis chronic kidney disease (CKD) (6, 16) are also at higher risk of NMSC, owing to the accumulation of uraemic toxins, further leading to chronic inflammation and oxidative DNA damage. Patients on chronic dialysis are at 5.3-fold risk of NMSC (excluding BCC) (14) in Denmark and 1.58-fold risk of NMSC (including all types of NMSC) (15) in Taiwan compared with the general population. Among patients with CKD in Denmark who are hospitalized and age < 70 years, there is a 4.8-fold risk of SCC and stationary risk of BCC compared with This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica. doi: 10.2340/00015555-3350 Acta Derm Venereol 2019; 99: 1275–1281

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