The research focuses on the causes, prevention and treatment of oesophageal and gastric cancer, and some conditions associated with these tumours, such as gastro-oesophageal reflux and obesity. 

Jesper Lagergren received his MD in 1989, became a specialist in surgery in 1996, got his doctorate in 1999, became associate professor in 2001, senior lecturer in 2003 and professor in 2006, all at Karolinska Institutet. In 2010 he became a Professor (Chair) at King's College, London. He has supervised 30 doctorate students to completed PhDs, including 14 as main supervisor. He has supervised 18 post-docs.

Professor Lagergren is since 2017 member of the Nobel Assembly at Karolinska Institutet. Among other scientific awards are: "Skandia´s Lennart Levi Prize" (2011), Leader of a research constellation judged as "Outstanding" by an external assessment (2010), "Distinguished Professor Award" (2009), "The primary research supervisor at Karolinska (2007), "Major Research scholarship in Surgery" the first time it was awarded (2004) and "Hirsch prize in cancer research (2002).

Among scientific awards are: "Skandia´s Lennart Levi Prize" (2011), Leader of a research constellation judged as "Outstanding" by an external assessment (2010), "Distinguished Professor Award" (2009), "The primary research supervisor at Karolinska (2007), "Major Research scholarship in Surgery" the first time it was awarded (2004) and "Hirsch prize in cancer research (2002).