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Trude Eid Robsahm,1,* Per Helsing,2,* Yngvar Nilssen,1 Linda Vos,1 Syed Mohammad H Rizvi,2,3 Lars A Akslen,4,5 Marit B Veierød6 1Cancer Registry of Norway, Oslo, Norway; 2Department of Dermatology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; 3Institute of Clinical Medicine, University of Oslo, Oslo, Norway; 4Centre for Cancer Biomarkers, Department of Clinical Medicine, Section for Pathology, University of Bergen, Bergen, Norway; 5Department of Pathology, Haukeland University Hospital, Bergen, Norway; 6Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway*These authors contributed equally to this work Purpose: The purpose of this study was to examine why Norway has the highest rate of mortality due to cutaneous melanoma (CM) in Europe. The Norwegian Malignant Melanoma Registry (NMMR) enables the study of clinical and histopathological characteristics of patients who die due to CM. Patients and methods: The NMMR and the Norwegian Cause of Death Registry provided data on the clinical and histopathological factors as well as the date and cause of death, through June 2015 for all first invasive CMs diagnosed in 2008–2012 (n=8087). Cox regression was used to estimate associations between clinical and pathological factors and CM-specific death. Multiple imputation was used to handle missing data. Results: The CMs were equally distributed between men (49.9%) and women (50.1%), and the median follow-up was 4.0 years (range: 0.08–7.5 years). Trunk was the most common anatomic site (48%), superficial spreading melanoma was the dominant melanoma subtype (68.2%), median Breslow thickness was 1.0 mm, ulceration was present in 23% of CMs, and 91.8% of cases were in a local clinical stage at diagnosis. Compared to women, men were diagnosed at a higher age, with thicker and more-often-ulcerated tumor, and more often were in advanced clinical stages. During follow-up, 1015 patients died due to CM, representing 52.8% of all deaths. The nodular subtype made up the dominant proportion of fatal CM cases (55.3% in women, 64.6% in men). Sex, age, anatomic site (trunk), T-stage, ulceration, clinical stage, and having a second primary CM were associated with increased risk of CM-specific death. Conclusion: Our data suggest that the high rate of mortality due to CM observed in Norway is attributable to the more advanced stage of the disease at diagnosis. Most high-risk cases occurred in male patients ≥70 years of age. Efforts to improve awareness and secondary prevention of CM, including warning signs of all melanoma subtypes, are required urgently and should be targeted toward men in particular. Keywords: cutaneous melanoma, mortality, prognostic factors, diagnostic delay, epidemiology

Yngvar Nilssen,1 Trond-Eirik Strand,1 Robert Wiik,2 Inger Johanne Bakken,3 Xue Qin Yu,4,5 Dianne L O'Connell,4–7 Bjørn Møller1 1Department of Registration, Cancer Registry of Norway, Oslo, 2Norwegian Patient Register Department, Norwegian Directorate of Health, Trondheim, 3Norwegian Institute of Public Health, Oslo, Norway; 4Cancer Research Division, Cancer Council NSW, 5School of Public Health, University of Sydney, 6School of Public Health and Community Medicine, University of New South Wales, Sydney, 7School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia Objective: To construct an updated comorbidity index (Patient Register Index [PRI]) using national data collections from Norway and compare its predictive ability of 1-year mortality with the Charlson Comorbidity Index (CCI). Materials and methods: Data regarding over 1.11 million patients registered in the Norwegian Patient Register in 2010 and 2011 were used to construct the PRI. The PRI was evaluated by comparing its model fit and discrimination with the CCI. Results: Compared with the CCI, the PRI weights decreased for six, increased for four, and were unchanged for seven diseases. When the PRI was added to the model including age and sex, the age effects were reduced by up to 38% for patients older than 50 years. All measures of model fit improved for the PRI model. Conclusion: Adjustment for comorbidity is especially important for patients 50 years of age or older, and its effect on 1-year mortality is almost comparable to the age effect. The PRI is based on more recent data than the CCI, and is more representative of the general population due to its construction. Keywords: comorbidity, National Patient Register, Charlson Comorbidity Index, predictive ability, patient-register index, prognostic value