Esophageal- and gastroesophageal junctional (GEJ) cancer is the sixth cause of cancer-related death worldwide. Some improvements in care are attributed to nationwide disease-specific registries, preoperative staging and increased understanding of mechanisms affecting patient selection. Surgery, however, is a cornerstone for treatment where minimally invasive surgery and increased understanding of perioperative physiology may be beneficial. The aims of this thesis were to validate the Swedish national registry for esophageal and gastric cancer (NREV) and to explore mechanisms in patient selection, perioperative physiology, treatment-related outcomes and staging.

A validation study with re-abstracted data on 400 patients determined NREV comparable to other similar registries and to have a completeness of 95.5 %. Overall accuracy was 91.1 % throughout the registry and timeliness to reporting was adequate.

In a cohort of 4112 patients from NREV, high education level was associated with an increased probability of being allocated to curative treatment, as was the presence of a multidisciplinary treatment conference. High education level was associated with improved survival.

By measuring intramucosal pH (pH_i) in 32 patients, to describe perfusion in the gastric conduit during esophagectomy, a reduction in perfusion was seen at all surgical steps altering vascular supply to the conduit but foremost after gastric tube construction by linear stapling. Patients with low pH_i on the first postoperative day were more prone to anastomotic insufficiency.

In 116 patients undergoing esophagectomy (65 open and 51 minimally invasive), a retrospective cohort study regarding surgical oncological results and postoperative complications was conducted. Lymph node yield was increased, peroperative blood loss and in-hospital stay were reduced with minimally invasive esophagectomy. Postoperative complications were unaffected by surgical approach. 

In a prospective study of nineteen patients, whole-body integrated PET/MRI was compared to PET/CT in preoperative staging. PET/MRI was safe and feasible. Accuracy and correlations between modalities were good regarding tumor characteristics and N- and M-staging. In T-staging there were discrepancies indicating differences between modalities.

The thesis presents data on the quality of NREV for future research and elaborates on patient selection, staging, perioperative physiology and treatment-related outcomes for patients with esophageal- and GEJ cancer.