Swedish Oesophago-Gastric Study

Swedish OEsophageal and GAstric tumour Study (SOEGAS)

Background Globally, oesophageal and gastric tumours are common with a high mortality. Oesophageal cancer and gastric cancer combined are often labelled upper gastrointestinal (GI) cancer. These tumours share many characteristics, including anatomy, risk factors, treatment and prognosis.

The main known risk factors for adenocarcinoma of the oesophagus and gastro-oesophageal junction are gastro-oesophageal reflux disease and obesity. The main risk factors for the other main histological type of oesophageal cancer, squamous cell carcinoma, are tobacco smoking and alcohol. The strongest known risk factor for gastric cancer is infection with Helicobacter pylori. Shared risk factors include dietary factors, tobacco smoking and heredity.

The curative treatment of upper GI cancers builds heavily on demanding surgery, where most of the oesophagus or stomach is resected. Except for surgery, most tumours are also treated with pre-operative, and sometimes postoperative, chemotherapy or chemoradiotherapy (6). The palliative treatment is also very important since the majority of patients are not eligible for curative treatment.

The survival is poor in patients diagnosed with upper GI cancer. This is mainly explained by late diagnosis since the symptoms are usually late and aggressive tumour biology, with early spread and recurrence. If detected early, the prognosis is excellent, but only a fraction of patients is detected at early tumour stages. The overall 5-year survival in oesophageal cancer is less than 20% and in gastric cancer it is less than 30% in most populations, including Sweden. The rate of patients found eligible for curative treatment including surgery is only 20-35%. Among operated patients the postoperative 5-year survival is 30-50%. It is crucial to conduct research that can improve the lives also of palliative patients.