ObjectiveOur study aimed to explore the effect of body mass index (BMI) change on cancer recurrence risk during the routine surveillance of endometrial cancer patients.MethodsData on patients with endometrial adenocarcinoma that had a staging procedure and continued follow-up was retrospectively collected. We compared patients’ BMI at time of surgery and during the last clinic follow-up. Univariate and multivariate analyses were performed to examine the effect of predictors on BMI change and the risk of recurrence.ResultsA total of 211 patients were included in the final analysis. The majority of patients had stage I disease (n=176, 89%) and endometrioid histology (n=178, 86%). Median follow-up time was 53.4 (standard deviation (SD) 40) months. The mean BMI was 30.4 kg/m2 (interquartile range (IQR) 25–34) at surgery compared with 30.9 kg/m2 (IQR 26–36) at last follow-up (p<0.001). The BMI increase was most pronounced in patients with endometroid histology that recurred, 31.6 (IQR 24–35) kg/m2at surgery compared with 33.5 (IQR 27–36) kg/m2at last follow-up (p=0.016). On multivariate analysis, age and BMI change were the only predictors that were significantly associated with the risk of recurrence (overall response (OR 1.07 (0.99–1.14), p=0.05, OR 1.37 (1.12–1.67), p=0.002, respectively).ConclusionPatients with endometroid endometrial cancer that had an increase in BMI during follow-up were at an increased risk for cancer recurrence compared with patients that did not change or had a decrease in BMI.