Abstract B015: Characterization of periprostatic adipose tissue in 27,748 Men: Links to visceral fat, aging, and factors relevant to prostate cancer

Abstract Background: While obesity is associated with increased risk of aggressive prostate cancer, mechanisms remain unclear. Periprostatic adipose tissue (PPAT), a visceral fat depot surrounding the prostate, may influence tumourigenesis via inflammatory and metabolic pathways. Prior research is limited to small studies of men with prostate cancer. This study characterises PPAT in a large, longitudinal cohort of prostate cancer-free men and examines its relationship with anthropometric, metabolic, demographic and lifestyle factors. Methods: Using magnetic resonance images (MRIs) from 27,748 male UK Biobank participants, an nnUNet autosegmentation model was used to quantify the volume of PPAT, defined as adipose tissue surrounding the prostate and anterior to the rectal wall. Spearman and partial correlation assessed the relationship of PPAT volume with other adiposity and anthropometric measures, and with markers of systemic metabolic health. Age and race-adjusted linear regression examined associations of log-transformed, standardised measures of PPAT volume, and of other adiposity measures, with demographic and lifestyle characteristics. Beta coefficients were exponentiated to estimate percentage differences. Results: Men had a median PPAT volume of 14ml (interquartile range (IQR), 8-23ml) and median abdominal visceral adipose tissue (VAT) volume of 4.7L (IQR 3.2-6.3L). PPAT volume correlated more strongly with VAT volume (r=0.61) than with other anthropometric measures, including body mass index (BMI; r=0.47) or waist circumference (r=0.48). Correlations of PPAT with systemic measures of metabolic health were weak (all r