Progress in the development of protein biomarkers of oesophageal and gastric cancers

Upper gastrointestinal cancers originating in the oesophagus and stomach often present late and have a very poor prognosis. Treatment options include surgery for localised disease but, increasingly, neoadjuvant chemotherapy and radiotherapy are being employed to improve outcome. There is often a variable response to neoadjuvant treatment between individual patients and side effects are relatively common. There is an urgent need for novel biomarkers of upper gastrointestinal cancer, not only to improve screening and early diagnosis of the oesophageal and gastric cancers when treatment options are potentially more effective, but also to accurately guide therapy in more advanced disease. The development of predictive biomarkers will also help to more effectively identify those patients that will benefit from targeted therapies. Although many promising results have been derived from these studies there remains a lack of validated clinically applicable biomarkers available for translation into routine clinical use. This review will provide an overview of the recent proteomic research on upper gastrointestinal cancer protein biomarker identification and validation. The challenges faced in the development of validated, clinically acceptable and accurate protein biomarkers will also be discussed, along with possible areas of future progress.