Table 1.

Data sources and dataset information

Data source	Variables
The Finnish Cancer Registry	Personal identification number (age, sex) Diagnosis number Date of cancer diagnosis Tumour stage
The Finnish Patient Registry	Personal identification number (age, sex) Hospital admissions data Admitting hospital Dates of admission and discharge Diagnosis codes Operations codes
The Population Register Centre	Marital status
Statistics Finland	Education level Date of death Causes of death
The Social Insurance Institution (Kela) registry	Dispensed drugs Type (Anatomical Therapeutic Chemical (ATC)-code) Date dispensed Amount of dispensed drug Sick leave (start date, end date) Pension information (start date)
Patient records	Tumour stage information Anaesthesia information Type of anaesthesia ASA classification* Surgery information Type of surgery Surgeon volume Bleeding Operation duration Complications According to the Esophagectomy Complications Consensus Group Clavien-Dindo classification Oncological treatment Neoadjuvant and adjuvant treatment Treatment modality Complications Pathology Tumour location and stage Lymph node yield and resection radicality Hospital and intensive care unit stay
Biobanks	Scans of original diagnostic slides