Abstract
OBJECTIVE: This study aimed to explore the associations between body composition and markers related to disease severity in young females newly diagnosed with breast cancer. METHODS: This cross-sectional study was conducted across two Oncology units. Inclusion criteria were females aged 20 to 40 years, newly diagnosed with ductal invasive breast cancer (stages I to IV), who had undergone abdominal computed tomography (CT) scans. CT images at the third lumbar vertebra (L3) level were used to assess body composition, including the cross-sectional area of skeletal muscle (cm²), skeletal muscle radiodensity (SMD, HU), intermuscular adipose tissue (IMAT, cm²), and total adipose tissue with its visceral and subcutaneous compartments. RESULTS: A total of 190 females were included in this analysis (median age: 35 years, quartile range: 31 to 37). 69.5% were diagnosed at stages III to IV. Patients at stages III to IV exhibited a significantly higher frequency of myosteatosis, assessed by high IMAT (P = 0.003). A higher IMAT was independently associated with higher odds of presenting with stages III to IV (OR (adjusted): 2.5, 95% CI 1.1 to 5.6). Similar results were found when evaluating molecular subtypes markers of disease severity (i.e., triple negative, luminal B, and overexpression of ER2-HER2+). Higher SMD values were inversely associated with luminal B, and overexpression of ER2-HER2+. CONCLUSION: Our findings demonstrate the potential significance of evaluating myosteatosis in young females newly diagnosed with breast cancer. The infiltration of adipose tissue and fat within skeletal muscle (i.e., myosteatosis) may hold implications for understanding disease severity, even when overall muscle mass quantity remain unchanged.