Ola Olén

What (purpose and aim)To quantify how risk of and mortality from major malignancies in IBD (e.g., colorectal cancer [CRC], small bowel cancer, lymphoma, liver cancer, pancreatic cancer, and skin cancer) in patients with inflammatory bowel disease (IBD) compared with the general populations of Sweden and Denmark has changed over the last 50 years. We also aim to disentangle the role of disease severity, disease duration, and treatment exposures (e.g. thiopurines and anti-TNF) in cancer development in IBD.HowRegister-based cohort studies: a Swedish-Danish collaboration where we have combined national healthcare registers with new databases, built by us, including detailed information about disease severity and degree of inflammation in the blood and gut. We have created the hitherto largest high-resolution database that for the first time makes it possible to study clinically crucial issues while handling shortcomings of earlier research. Why (Significance)Ultimately, this project has the potential to lead to a currently missing reliable risk prediction tool regarding relevant malignancies in different IBD sub-groups and will contribute significantly to development of updated evidence-based guidelines regarding treatment and cancer surveillance tailored to the individual IBD-patient.