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<0.3) and attenuated (all r<0.1) after adjusting for VAT using partial correlation. While VAT volume was 19% higher in older (65+ years) relative to younger men (<45 years), PPAT volume more than doubled over this age range (+104%). By contrast, BMI was lower in older vs younger men (-19%). While black men had higher BMI relative to white men (+20%), they had less VAT (-56%) and PPAT (-31%). Associations of PPAT volume with lifestyle characteristics followed similar patterns as for VAT, although slightly less pronounced. Men completing higher level education vs high school only had less PPAT (-14%) and less VAT (-23%). Relative to sedentary men, those reporting physical activity equating to an hour moderate intensity or 30 minutes high intensity activity per day had less PPAT (-20%) and less VAT (-28%). Men with benign prostatic hyperplasia (BPH) had higher PPAT (+9%) but no significant difference in VAT volume. Conclusions: In the largest study to date in prostate cancer-free men, we find that PPAT is closely associated with visceral obesity and more strongly associated with aging than other adiposity measures. Weak correlations of PPAT with measures of systemic metabolic health imply any influence on prostate growth and tumorigenesis may be through local effects. Associations of PPAT volume with lifestyle characteristics may support its modifiable nature, potentially through interventions to reduce visceral adiposity. Citation Format: Jade Dorrian, Emma H. Allott, Ryan O’Keeffe, Angela O'Neill, Sarah Winter, Joshua Atkins, Mahboubeh Parsaeian, Karl Smith-Byrne, Amy Dawes, Vilmundur Guðnason, Ruth Travis, Tom Gaunt, Michelle Leech. Characterization of periprostatic adipose tissue in 27,748 Men: Links to visceral fat, aging, and factors relevant to prostate cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Prostate Cancer Research and Treatment; 2026 Jan 20-22; Philadelphia PA. Philadelphia (PA): AACR; Cancer Res 2026;86(2_Suppl):Abstract nr B015.