Complications following surgery remain common in colorectal cancer, despite care having become increasingly standardised. In his thesis, “Preoperative predictors for outcome in colorectal cancer”, Felix Bjerregaard has investigated which factors influence the risk of complications and how patients can be prepared for surgery to improve outcomes.
Colorectal cancer is the third most common form of cancer in Sweden and worldwide. For most patients, surgery is an important part of treatment, but complications following surgery remain a significant problem. In his thesis, Felix Bjerregaard , a doctoral student at the Department of Clinical Sciences, Danderyd Hospital , studied both risk factors for complications and ways of improving patients’ readiness for surgery.
Two key questions
The thesis had two main objectives. The first was to identify patient-related factors associated with poorer short-term outcomes following colorectal surgery. The second was to investigate whether measures taken before surgery, known as preoperative optimisation, can reduce the risk of complications.
Photo: Monica Ringheim
“We wanted both to understand which patients are at greatest risk of complications and to investigate how we can improve their condition before surgery,” says Felix Bjerregaard.
The thesis analysed factors linked to anastomotic leakage and postoperative ileus, two common complications following colon surgery. The research included both registry-based studies and a randomised clinical trial involving patients undergoing colorectal cancer surgery at Danderyd Hospital.
Frailty and functional ability matter
The results suggest that surgical complications are primarily associated with factors that affect how technically demanding the operation is. Serious complications, on the other hand, appear to be more frequently linked to the patient’s frailty and overall functional ability.
Part of the thesis also examined multimodal preoperative optimisation, which includes prehabilitation and nutritional support prior to surgery.
“Our results show that this type of intervention can reduce the incidence of serious postoperative complications in patients with reduced baseline functional capacity,” says Felix Bjerregaard.
Can help healthcare providers choose the right interventions
According to Felix Bjerregaard, the results could be used to better identify patients at high risk of complications following surgery. They could also provide guidance on which patients are most likely to benefit from supportive interventions before surgery.
The next step in the research will be to introduce a structured model for the preoperative optimisation of patients with reduced functional capacity ahead of colorectal cancer surgery at Danderyd Hospital.
“The aim is to confirm our findings and investigate how the approach works in clinical practice,” says Felix Bjerregaard.
The thesis work was supervised by Ulf Gustafsson at Karolinska Institutet’s Department of Clinical Sciences, Danderyd Hospital, and the Department of Molecular Medicine and Surgery . The public defence will take place on 23 October 2026.
