The association between body mass index and molecular subtypes in endometrial carcinoma

This study aims to investigate the relationship between body mass index (BMI) and molecular subtypes of endometrial carcinoma using an immunohistochemistry (IHC)-based classification approach.

We analyzed a consecutive series of endometrial cancer cases undergoing surgical staging in southern Alberta (2019-2021). Molecular classification was determined through IHC-based molecular typing, incorporating p53 and mismatch repair (MMR), and further characterized with the addition of ER and PR. BMI associations with molecular classification were assessed using t-tests. Hormone receptor status was further examined in a separate cohort of MMRd endometrial cancer patients undergoing surgical staging at Foothills Medical Centre (Alberta, Canada).

Among 289 cases, comprising various histological subtypes, the pNSMP subtype exhibited the highest average BMI (33.93 kg/m²) compared to the p53 abnormal subtype (30.40 kg/m², p = 0.02). The MMRd subtype had an average BMI of 33.22 kg/m². While there were no significant BMI differences between FIGO grade 1 and grade 2/3 tumours in the pNSMP or MMRd, a trend toward higher BMI in grade 1 tumours versus grade 2/3 tumours in the MMRd was observed (p = 0.13). A separate cohort of 53 MMRd endometrial carcinomas revealed that FIGO grade 1 tumours were associated with higher BMI (p < 0.05) and more frequent ER/PR expression compared to grade 2/3 tumours (p < 0.05).

This study suggests an association between obesity and NSMP endometrial carcinoma. The relationship between BMI and low-grade MMRd endometrial carcinomas with increased ER/PR expression warrants further exploration.