Dr. Boleij is a biomedical scientist focusing on the gastrointestinal microbiome in colorectal cancer (CRC) development. She obtained her PhD at the Department of Laboratory Medicine of the Radboudumc where she discovered that infections with the opportunistic pathogen Streptococcus gallolyticus are associated with the presence of tumors in the gastrointestinal tract. Infections with this bacterium are therefore a silent sign for CRC. In 2012 she obtained her PhD-degree and was awarded a Rubicon grant of NWO to conduct research on oncotoxin producing Bacteroides fragilis at Johns Hopkins Medical Institutions. She found that the oncotoxin was frequently detected in the gut mucosa of CRC patients and elucidated part of the epithelial signaling mechanism of this bacterial oncotoxin using cell culture and mice colitis models. In 2014 she started her research at the Department of Pathology and was awarded a Veni-grant from NWO. With her research group Dr. Boleij focuses on members of the microbiome with potential cancer promoting or inhibiting effects especially in patients with a high risk for CRC such as patients with chronic inflammation or a hereditary predisposition. The ultimate goal is to understand why the microbiome changes during cancer development, whether microbes play a role in the pathogenesis of CRC and whether microbes can predict if patients are at risk for CRC.