ObjectivesAim of this study was to determine whether peri-operative immunonutrition can decrease complications and the length of stay (LOS) in malnourished ovarian cancer patients.Study designPatients suspicious for advanced ovarian cancer before histopathological diagnosis and a nutritional risk score (NRS) ≥ 3 received oral immune-modulating diets (IMDs) for 5 days pre-operative and at least 5 days post-operative. Parameters for clinical outcome were infectious and non-infectious complications during hospital stay, and time of hospitalization. The results were compared with malnourished ovarian cancer patients of a previous study without any additive nutritional support (standard clinical diet/nutrition).ResultsThe infectious and non-infectious complication rate in the interventional group (IG) N = 28 was 42.9%, similar to the control group (CG) N = 19 with 42.1%, whereas the rate of infectious complications in the IG (21.4%) was slightly lower compared to the CG (26.3%). The median LOS of the IG was 18 days, and therefore, longer than LOS of the CG (15 days). Regarding the patients’ compliance pre-operative 78.6% of the patients took the IMDs in an optimal and sufficient amount. Whereas after surgery, only eight (28.6%) patients were able to take IMDs in optimal and sufficient amount.ConclusionsThe current study showed no improvement of the complication rate or the time of hospitalization due to additional peri-operative immunonutrition in malnourished ovarian cancer patients. However, a trend towards the reduction of infectious complications could be seen in the IG.