Cancers of the skin are the most commonly occurring cancers in humans. In fair-skinned populations, up to 95% of keratinocyte skin cancers and 70-95% of cutaneous melanomas are caused by ultraviolet radiation and are thus theoretically preventable. Currently, however, there is no comprehensive global advice on practical steps to be taken to reduce the toll of skin cancer. To address this gap, an expert working group comprising clinicians and researchers from Africa, America, Asia, Australia, and Europe, together with learned societies (European Association of Dermato-Oncology, Euromelanoma, Euroskin, European Union of Medical Specialists, and the Melanoma World Society) reviewed the extant evidence and issued the following evidence-based recommendations for photoprotection as a strategy to prevent skin cancer. Fair skinned people, especially children, should minimise their exposure to ultraviolet radiation, and are advised to use protective measures when the UV index is forecast to reach 3 or higher. Protective measures include a combination of seeking shade, physical protection (e.g. clothing, hat, sunglasses), and applying broad-spectrum, SPF 30 + sunscreens to uncovered skin. Intentional exposure to solar ultraviolet radiation for the purpose of sunbathing and tanning is considered an unhealthy behaviour and should be avoided. Similarly, use of solaria and other artificial sources of ultraviolet radiation to encourage tanning should be strongly discouraged, through regulation if necessary. Primary prevention of skin cancer has a positive return on investment. We encourage policymakers to communicate these messages to the general public and promote their wider implementation.

1st Department of Dermatology School of Medicine Faculty of Health Sciences Aristotle University Thessaloniki Greece

1st Department of Dermatology University of Athens School of Medicine Andreas Sygros Hospital Athens Greece

Belgian Cancer foundation Brussels Belgium

Brown University and 5 A Medical Centre Providence RI USA

Centre for Dermatooncology Department of Dermatology Eberhard Karls University Tuebingen Germany

Department of Clinical Internal Anesthesiological and Cardiovascular Sciences Sapienza University Rome Italy

Department of Dermatology and Venereology Centro Hospitalar Universitário de Coimbra Coimbra Portugal

Department of Dermatology and Venereology of the Hospital Clinics Giuliano Isontino Maggiore Hospital Trieste Italy

Department of Dermatology and West German Cancer Centre University Hospital Essen and German Cancer Consortium Campus Essen and National Centre for tumour Diseases West Campus Essen Germany

Department of Dermatology Barts Health NHS Trust and Centre for Cell Biology and Cutaneous Research Blizard Institute Barts and the London School of Medicine and Dentistry Queen Mary University London UK

Department of Dermatology Erasme Hospital Université Libre de Bruxelles Brussels Belgium

Department of Dermatology Faculty of Medicine Military Medical Academy Belgrade Serbia

Department of Dermatology Ghent University Hospital Ghent Belgium

Department of Dermatology Henry Ford Health Detroit MI USA

Department of Dermatology Hospital Clínic de Barcelona University of Barcelona IDIBAPS Barcelona and CIBERER Barcelona Spain

Department of Dermatology Ruhr University Bochum Bochum Germany

Department of Dermatology Sapporo Medical University Sapporo Japan

Department of Dermatology University Hospital Schleswig Holstein Campus Kiel Kiel Germany

Department of Dermatology University of Modena and Reggio Emilia Modena Italy; Azienda Unità Sanitaria Locale IRCCS di Reggio Emilia Skin Cancer Centre Reggio Emilia Italy

Department of Dermatology Venerology and Allergology Frankfurt University Hospital Frankfurt Germany

Department of Dermatovenereology Charles University 3rd Medical Faculty and University Hospital Kralovske Vinohrady Prague Czech Republic

Department of General and Oncologic Dermatology Ambroise Paré hospital APHP and EA 4340 Biomarkers in cancerology and haematooncology UVSQ Université Paris Saclay 92104 Boulogne Billancourt France

Department of Medical Oncology Gustave Roussy and Paris Saclay University Villejuif France

Department of Social and Behavioural Sciences Public Health Campus Boston MA USA

Dermatologia Dipartimento di Medicina e Chirurgia Traslazionale Università Cattolica del Sacro Cuore Rome Italy; UOC di Dermatologia Dipartimento di Scienze Mediche e Chirurgiche Fondazione Policlinico Universitario A Gemelli IRCCS Rome Italy

Dermatology Department Elias University Hospital Carol Davila University of Medicine and Pharmacy Bucharest Romania

Dermatology Department of Biotechnological and Applied Clinical Sciences University of L'Aquila L'Aquila Italy

Faculty of Medicine Centre of Dermatovenereology Clinic of Infectious Diseases and Dermatovenereology Vilnius University Vilnius Lithuania

France Nantes University Inserm 1302 INCIT F 44000 Nantes France

Frazer Institute The University of Queensland Dermatology Research Centre Brisbane Queensland Australia

GROW School for Oncology and Reproduction Maastricht University Medical Centre Maastricht the Netherlands; Department of Dermatology Maastricht UMC Comprehensive Cancer Centre Maastricht the Netherlands

International Prevention Research Institute Dardilly France

Medical and Surgical Dermatology Service Hospital Universitario Virgen Macarena Sevilla Spain

Population Health Department QIMR Berghofer Medical Research Institute Brisbane QLD Australia

Private Practice Cape Town South Africa

Skin Cancer Centre Laboratory for Molecular Cell Biology Elbe Hospital Buxtehude Buxtehude Germany

Université Paris Cite AP HP Dermato oncology and CIC Cancer institute APHP Nord Paris Cité France; INSERM U976 Saint Louis Hospital Paris France

University of New Mexico Comprehensive Cancer Centre Albuquerque USA

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