A critical evaluation of diagnostic tools in abdominal surgery

This thesis discusses two contrasting approaches of risk-tailored medicine in different fields of abdominal surgery.
The first part focuses on an intensified use of diagnostic tools in high-risk patients. An example of a more tailored follow-up strategy is currently being investigated in the COLOPEC 2 trial. This randomised controlled trial aims to determine the value of second and third look diagnostic laparoscopy during the follow-up of patients with pT4 colon cancer for the detection of clinically occult peritoneal metastases (PM). To maximise the yield of diagnostic tools, identification of high-risk patients is essential. An experimental mouse model provided insight in the (varying) ability and pattern of peritoneal dissemination of 15 extensively characterised human colorectal cancer cell lines. We found evidence for a role of KRAS pathway activation in the development of PM. In an international, multicentre study, we learned that pT4a colon cancer (penetration of the visceral peritoneum) was associated with a significantly higher risk of developing metachronous PM as compared to pT4b tumours (direct invasion of other organs/structures). In combination with other risk factors, these observations might help to identify patients at highest risk for developing peritoneal metastases.
The second part of this thesis describes a method to reduce the use of diagnostic tools in low-risk patients. The FANCY study was a multicentre, prospective, cross-sectional study investigating the oncological safety and potential cost savings of selective histopathological examination following appendectomy and cholecystectomy performed for presumed benign diseases. This study provided robust evidence that a selective policy of histopathological examination following appendectomy and cholecystectomy for presumed benign diseases is oncologically safe and provides significant cost savings. In fact, both routine and selective histopathological examination resulted in clinical consequences which were more often harmful than beneficial for patients. This suggests that even complete abandonment of histopathological examination of these specimens might be justified with even higher cost savings.