The Prognostic Impact of Body Composition Assessment By Computed Tomography in Adult Patients with Newly Diagnosed Acute Lymphoblastic Leukemia

Introduction: Body composition has been proposed to play an important role in clinical outcomes in patients with cancer, and low muscular mass has been associated with worse overall survival (OS) and disease-free survival (DFS) in different malignancies. Computed tomography (CT) assessment of body composition at the level of L3 vertebral body provides a reliable high-precision method for quantifying muscular mass, subcutaneous fat, and visceral fat with validated cutoff values. This method has been used in many hematological malignancies like acute myeloid leukemia and lymphoma, with promising results regarding correlation with disease outcomes, although it has not been explored in adult patients with acute lymphoblastic leukemia (ALL). Methods: This is a retrospective study from a tertiary care center in Mexico City that included adult patients with a new diagnosis of ALL according to the WHO criteria, who had a CT scan at the level of L3 done within 2 weeks of starting induction chemotherapy between 2014 and 2023. Using HorosTM software (version 3.3.6; Horos Project, United States), skeletal muscle, visceral fat, and subcutaneous fat areas (measured in cm 2) were quantified from an axial slice at the level of the L3 vertebral body using established Hounsfield unit (HU) thresholds for each specific tissue. These measurements were indexed for height and reported in cm2/m2. A low muscular mass was defined according to a 2011 consensus on cancer cachexia as a skeletal muscle index (SMI) < 55 cm 2/m 2 in men and < 39 cm 2/m 2 in women. Optimal cutoff points for subcutaneous adipose tissue index (SATI) and visceral adipose tissue index (VATI) to correlate with mortality were obtained with a receiver operating characteristic (ROC) curve. Results: Ninety patients with a new diagnosis of ALL were included in the analysis. The median age at diagnosis was 37 years (range, 18-72), and 47.8% were male. Baseline characteristics and treatments are detailed in Table 1. The median SMI of the whole cohort was 39.64 cm 2/m 2 (range, 23.48-67.91). Sixty-nine patients (76.7%) fulfilled the criteria for low muscular mass. SMI was higher in male patients (43.9 cm 2/m 2 (27.1-65.1) vs. 35.1 cm 2/m 2 (23.5-67.9), p < 0.001). SATI was higher in patients with a body mass index (BMI) > 25 kg/m 2 (87.3 cm 2/m 2 (29.8-286.6) vs. 38.3 cm 2/m 2 (6.1-157.5), p < 0.001) and in female patients (84.2 cm 2/m 2 (6.1-286.6) vs. 44.2 cm 2/m 2 (8.1-157.5), p < 0.001). VATI was higher in patient