Allostatic load, neutrophil-to-lymphocyte ratio, and body composition in patients with metastatic prostate cancer.

e17135 Background: Allostatic load (AL), a composite biomarker index of multisystem physiologic dysregulation, and neutrophil-to-lymphocyte ratio (NLR), a systemic inflammatory marker, have been independently related to poor prognosis when ascertained at diagnosis in various cancers (e.g., breast, colorectal). However, their associations with adverse body composition phenotypes (sarcopenia, sarcopenic obesity or myosteatosis) in metastatic prostate cancer (MPC) remain largely unexplored. This study examines associations between AL, NLR and adverse body composition phenotypes in men with newly diagnosed MPC. Methods: A cross-sectional study using clinical data collected from the electronic medical records was conducted in adult men with newly diagnosed MPC. Eligibility criteria included a CT scan at the L3 vertebral level and laboratory data at date of cancer diagnosis. AL was calculated using nine clinical biomarkers (range 0–9). NLR was calculated by dividing an absolute neutrophil by an absolute lymphocyte count. Sarcopenia, sarcopenic obesity, and myosteatosis were defined using validated CT-based thresholds for skeletal muscle (SM) quantity and SM radiodensity (i.e., a marker of SM quality). Multivariable logistic regression was used to evaluate associations among AL, NLR, body composition phenotypes, and age. Results: Among 144 eligible men (35.5% White, 39.3% Black/African American, and 23.5% Latinx, mean age 69.6 ± 10.9 years), 64% had sarcopenia, 12.6% had sarcopenic obesity, and 57.9% had myosteatosis at diagnosis. AL was positively correlated with NLR (rho = 0.317, p < 0.001). In adjusted models, AL was associated with higher odds of sarcopenia (OR = 1.61, p = 0.004), sarcopenic obesity (OR = 1.99, p = 0.001), and myosteatosis (OR = 1.42, p = 0.031). Conversely, elevated NLR was negatively associated with sarcopenia (OR = 0.91, p = 0.006), sarcopenic obesity (OR = 0.648, p = 0.006), and myosteatosis (OR = 0.897, p = 0.008). Conclusions: In men with MPC, elevated AL was positively associated with all three adverse body composition phenotypes at diagnosis while NLR was negatively associated. These findings underscore the potential link between chronic exposure to stress, inflammation, and the development of adverse body composition phenotypes of muscle loss and muscle quality in men with newly diagnosed MPC.