PD683 - EARLY DETERIORATION OF SKELETAL MUSCLE QUALITY DURING NEOADJUVANT TREATMENT IN OPERABLE OESOPHAGOGASTRIC CANCER DESPITE PREHABILITATION

PD683

EARLY DETERIORATION OF SKELETAL MUSCLE QUALITY DURING NEOADJUVANT TREATMENT IN OPERABLE OESOPHAGOGASTRIC CANCER DESPITE PREHABILITATION

Y. Deswysen^1,2,*, E. Danse³, P. Trefois³, A. Collard⁴, M. Van den Eynde^5,6, N. Lanthier^2,6

¹UpperGI surgical unit, Service de Chirurgie et Transplantation Abdominale, Cliniques universitaires Saint-Luc, UCLouvain, ²Laboratoire de gastroentérologie et d’hépatologie, Institut de Recherche Expérimentale et Clinique, UCLouvain, ³Service de Radiologie, Cliniques universitaires Saint-Luc, UCLouvain, ⁴Cellule statistique, Clinical Trial Center, Cliniques universitaires Saint-Luc, UCLouvain, ⁵Service d’Oncologie Médicale, Cliniques universitaires Saint-Luc, Institut Roi Albert II, UCLouvain, ⁶Service d’Hépato-gastroentérologie, Cliniques universitaires Saint-Luc, UCLouvain, Brussels, Belgium

Rationale: Neoadjuvant treatments in operable oesophagogastric cancer may induce early nutritional and metabolic alterations despite prehabilitation. The respective effect of chemotherapy (Chem) and chemoradiotherapy (ChemRx) on muscle parameters, particularly myopenia and myosteatosis, remains unclear.

Methods: We conducted an observational study including patients treated with neoadjuvant therapy (2019–2023) with CT scans at diagnosis (T0) and pre-surgery (T1). Skeletal muscle index (SMI) and density (SMD) were assessed at L3. BMI, albumin, CRP, platelets, neutrophils, lymphocytes, neutro/lymphocytes ratio (NLR) and platelets/lymphocytes ratio (PLR) were recorded. Myopenia and myosteatosis were defined using Martin’s criteria.

Results: Fifty-nine patients were included: Chem (n=29) and ChemRx (n=30), with a mean 129-day interval between T0 and T1. Myopenia remained stable (62.7% vs 60.0%), whereas myosteatosis increased (87.6% vs 90.0%). SMD significantly declined between T0 and T1 (median Δ −2.87 HU; p<0.001), while SMI (median Δ −0.08 cm²/m²; p=0.19), albumin (median Δ 0.00; p=0.511) and BMI (median Δ −0.43; p=0.072) remained unchanged. Platelets and lymphocytes decreased, whereas NLR increased. SMD decline did not differ between groups (p=0.21). ChemRx was associated with greater reductions in neutrophils (p=0.001) and lymphocytes (p<0.001), and a greater PLR increase (p<0.001).

Conclusion: Skeletal muscle quality deteriorates during neoadjuvant therapy, despite stable BMI and muscle mass, highlighting a disconnect with conventional nutritional markers and an underestimation of early muscle impairment. Changes in PLR and NLR likely reflect radiotherapy-induced bone marrow effects. Integrating myosteatosis into routine evaluation may improve risk stratification and support targeted nutritional interventions during neoadjuvant treatment.

Disclosure of Interest: None declared