The role of fat distribution and inflammation in the origin of endometrial cancer, study protocol of the ENDOCRINE study

BACKGROUND: Obesity is a growing problem worldwide, especially in countries with improved socioeconomic circumstances. Also, in the Netherlands the incidence of overweight and obesity is rising. There is increasing evidence on the association between obesity and tumorigenesis. Of all cancer types, endometrial cancer (EC) has the strongest positive correlation with obesity. Obesity is generally defined as a body mass index (BMI) >30, yet does not cover the differences in fat distribution in visceral and subcutaneous compartments. Visceral fat is assumed to be relatively more metabolically active and likely negative prognostic biomarker in non-endometrioid EC. Whereas subcutaneous fat is mainly responsible for oestrogen production through increased aromatase activity. OBJECTIVE: The aim of this study is to compare hormone levels and inflammatory markers after bilateral salpingo-oophorectomy (BSO) in obese and non-obese patients. Secondary objectives are to compare the effect of fat distribution and diagnosis (benign vs. EC) on the observed changes in hormone levels and inflammatory markers, and to compare the effect of BSO on menopausal complaints. METHODS: Prospective multicentre observational cohort study. A total of 160 patients will be included, of which 80 patients with a normal BMI (18–25 kg/m2) and 80 patients with an obese BMI >32–35 kg/m2. Preoperative abdominal CT will be performed and fasting venous blood samples are obtained for hormone levels and inflammation markers analysis. During surgery, adipose tissue biopsies of subcutaneous and visceral (omental and intestinal epiploic fat) compartments will be collected and stored fresh frozen. In addition a fasting blood draw six weeks after surgery will be obtained. All subjects will fill in two questionnaires before surgery and one after surgery. DISCUSSION: We hypothesize that BMI, the type of fat distribution, and possibly the underlying pathology significantly influence in hormone levels, and systemic inflammation changes after BSO. Previous studies have found several clues for a relationship between obesity and endometrial cancer. We expect that our study will contribute to pinpoint the exact differences between ‘healthy obesity’ and ‘unhealthy obesity’ and will help to identify patients that are more at risk of developing cancer (or possibly suffer from other related problems such as cardiovascular problems e.g.).