Geographical residency influences pancreatic cancer survival: a Danish nationwide population-based cohort study

Abstract

Introduction: It is unknown if geographical residency affects pancreatic cancer survival in a tax-financed health-care system. Method: We conducted a population-based cohort study of all patients diagnosed with histologically verified pancreatic ductal adenocarcinoma (PDAC) in Denmark during 2004-2015. We used nationwide registries to assemble our cohort and collect information on demographic characteristics, comorbidity, cancer-directed treatment, and vital status. We followed patients from the date of PDAC diagnosis until death, emigration, or October 1, 2017. We stratified patients into three calendar periods according to year of diagnosis (2004-2007, 2008-2011, and 2012-2015). We used Cox proportional hazards model to compute hazard ratios (HRs) with associated 95% confidence intervals (CIs) of death, comparing patients in rural and urban areas. HRs were adjusted for age, sex, comorbidity, tumor stage, and localization. In a sub-analysis, we also adjusted for cancer-directed treatment. Results: We identified 7,210 patients diagnosed with PDAC during the study period. Median age was 68.8 years (inter-quartile range: 62.1-75.2 years), and 51.5% were men. The majority (61.7%) lived in an urban area at the time of diagnosis. During the latest calendar period, we observed an improved survival among PDAC patients residing in urban areas compared with patients living in rural areas (adjusted HR: 0.89; 95% CI: 0.82-0.97), even after adjustment for cancer-directed treatment (adjusted HR: 0.88; 95% CI: 0.76-1.01). Conclusions: Patients with PDAC residing in urban areas have a better survival compared with patients living in rural areas in the later years.