Introduction Lymphocyte to monocyte ratio (LMR) is an independent positive prognostic marker in endometrial cancer (EC). The aim of this study is to assess the relationship between LMR, obesity and weight loss in EC.

Methods Three retrospective cohorts were analysed. Cohort A included 147 women with EC, Cohort B included 71 age-matched women with obesity undergoing metabolic surgery and Cohort C included five patients (BMI > 40 kg/m2) with either EC (n=4) or complex atypical hyperplasia (CAH) (n=1) who underwent metabolic surgery without hysterectomy. Preoperative full blood counts, BMI, stage, grade, lymphovascular invasion and histological subtype of patients with EC were analysed.

Results 62.5% percent of women with EC were obese (BMI>30) and BMI correlated with LMR (R²=0.3, p=0.011) in Cohort A. Mean LMR in women with EC and obesity was 3.78 (SEM 0.18), 3.41 (SEM 0.23] in the nonobese women and 3.95 (SEM 0.15) in the obese control group. Mean lymphocyte count in the obese EC group was 1.9 (SEM 0.07), 1.7 (SEM 0.11) in the non- obese EC group and 2.2 (SEM 0.21) in the control patients (p=0.001). In Cohort C, metabolic surgery caused a 23-29% weight loss and the LMR decreased in three of five women. Mean LMR preoperatively was 4.18 (SEM 0.61) compared to 3.33 (SEM 0.4). This was due to a reduction in lymphocytes.

Conclusion/Implications Women with obesity and EC have significantly lower lymphocyte counts than age matched controls with obesity suggesting that women with obesity and endometrial cancer may have impaired systemic immune response.