Skeletal muscle radiodensity and insulin sensitivity in patients with rectal cancer

Introduction/Justification The assessment of skeletal muscle attenuation via computed tomography plays a crucial role in identifying myosteatosis among cancer patients. Myosteatosis, characterized by ectopic adipose tissue infiltration in skeletal muscles, has been linked to poor prognosis in various cancers. However, its implications specifically in rectal cancer remain uncertain. Studies have shown that myosteatosis correlates with increased insulin resistance, highlighting the need for further investigation in clinical settings. Objectives This study aimed to investigate the relationship between insulin sensitivity and skeletal muscle radiodensity in patients recently diagnosed with rectal cancer. Materials and Methods A cross-sectional study design was employed, inviting patients diagnosed with rectal cancer to participate. Insulin sensitivity was assessed using the M-value obtained from euglycemic hyperinsulinemic clamp tests. Skeletal muscle analysis was conducted using computed tomography (CT) images of the third lumbar vertebra processed with SliceOmatic software. Skeletal muscle was defined within the attenuation range of -29 to +150 Hounsfield Units (HU), while intermuscular adipose tissue was defined within -190 to -30 HU. The mean skeletal muscle radiodensity (SMR) was reported. Demographic and clinical data were collected from medical records. Statistical analyses were performed using Stata Corp LP® version 17.0 software. The study protocol received approval from the Institutional Review Board (CAAE: 91217418.2.0000.5404). Results The analysis included a total of 33 patients, predominantly male (67%) with ages ranging from 55 to 70 years (58%). Patients across stages I to IV were represented, with 48% in stage III, 11% in stage I, 11% in stage II, and 30% in stage IV. Overweight and obesity were diagnosed in 37.5% and 30% of the sample, respectively. Common comorbidities included diabetes (21%), hypertension (60%), and dyslipidemia (21%). The M-value adjusted for Total Body Weight (TBW) demonstrated a significant association with Skeletal Muscle Radiodensity (rho = 0.3926, p = 0.0269), whereas no statistical difference was observed when adjusting for Free Fat Mass (FFM) (p = 0.1769). Conclusion In conclusion, our findings suggest a moderate positive association between insulin sensitivity and skeletal muscle radiodensity in rectal cancer patients.