Study design. The study is a retrospective, descriptive register study based on data from a prospectively maintained database. The study is a comparison of two cohorts, all Inuit patients living in Greenland, who had pancreatic operations for pancreatic and periampullary tumors - either preoperatively verified or suspected - at Rigshospitalet, Copenhagen University Hospital from 31. January 1999 to 31. January 2021. Danish patients living in Greenland were not included in the study. Inuit patients were compared with a cohort of Danish patients with same diagnosis and same range of age operated during the same period at the hospital. All diagnoses were histologically verified. Data recruitment include all patients operated between January 31, 1999 and January 31, 2021 with follow-up until December 31 after which data will be evaluated. The study is reported according to the STROCSS guidelines (www.strocssguideline.com).

Study population. The study includes 2326 consecutive patients, 47 inuit and 2279 Danish patients between 41 and 79 years (age range based on the inuit patients). There are 1,208 patients with malignant tumours of whom 1,020 have adenocarcinoma.

Data collection Data are collected from our prospectively maintained database of pancreatic operations, from the electronic hospital record systems Orbit and EPIC, the Danish National Pathology Data Registry, and from the National Register of Death. All Danish Nationals including citizens in Greenland have a unique Central Person Registration number that enables searching of health data.

Outcomes. Relevant postoperative complications are recorded in the study and include leakage from the pancreatic, bile or gastrojejunal anastomosis, intraabdominal hemorrhage and abscess formation or other complications with severe or fatal outcome. Outcomes are defined as postoperative complications and mortality assessed during 30- and 90-days and overall survival (OS) defined as the time from surgery to death from any cause or censoring at time of last follow-up. Hospitalization is defined as postoperative stay until discharge. In-hospital mortality is defined as all deaths from time of admission until discharge. Cancer specific mortality is defined as death from adenocarcinoma after other causes are censured.

Statistics. Data are presented as median and range if not otherwise stated. Categorial data are presented as numbers or percentage and are analyzed with Fisher's exact test. Non-parametric continuous data between subgroups are analyzed with the Mann-Whitney test. The Kaplan-Meier method and the cumulative incidence function with correction for competing risks are used to estimate OS and the log-rank test to examine the differences between curves. The reference population is an age and sex matched Danish standard population. A p \< 0.05 is considered statistically significant. Statistical analysis is performed with GraphPad Prism software version 6.05. (GraphPad, La Jolla, CA).

Ethics. The study is a descriptive study and conducted in accordance with the principles stated in the Declaration of Helsinki. No approval is required according to the Danish National Health Board. The study is an observational, retrospective quality assurance project according to the guidelines of the Danish Health Data Authority (http://Sundhedsdatastyrelsen.dk). No approval is required according to the Danish National Health Board. In this respect it has to be noticed that a major part of the Greenlandic and Danish patients had died before the study was initiated, and the Regional Ethical Committee of the Capital Region of Denmark provided exemption for the study. The use of register data follows the General Data Protection Regulation of the European Union and the Danish Data Protection Agency. Patients' written consent for using health data was obtained before operation. The study and the use of data were consented by the hospital ethical