Association of Body Composition with Long-Term Survival in Non-metastatic Rectal Cancer Patients

PurposeWe evaluated the association of body composition with long-term oncologic outcomes in non-metastatic rectal cancer patients.MethodsWe included 1,384 patients with stage(y)0-III rectal cancer treated at Asan Medical Center between January 2005 and December 2012. Body composition at diagnosis was measured using abdomino-pelvic computed tomography (CT). Sarcopenia, visceral obesity (VO), and sarcopenic obesity (SO) were defined using CT measured parameters such as skeletal muscle index (total abdominal muscle area, TAMA), visceral fat area (VFA), and VFA/TAMA. Inflammatory status was defined as a neutrophil-lymphocyte ratio of ≥3. Obesity was categorized by body mass index (≥ 25 kg/m²).ResultsAmong the 1,384 patients, 944 (68.2%) had sarcopenia and 307 (22.2%) had SO. The 5-year overall survival (OS) rate was significantly lower in sarcopenic patients (no sarcopenia vs. sarcopenia; 84% vs. 78%, p=0.003) but the 5-year recurrence-free survival (RFS) rate was not different (77.3% vs. 77.9% p=0.957). Patients with SO showed lower 5-year OS (79.1% vs. 75.5% p=0.02) but no difference in 5-year RFS (p=0.957). Sarcopenia, SO, VO, and obesity were not associated with RFS. However, obesity, SO, age, sex, inflammatory status, and tumor stage were confirmed as independent factors associated with OS on multivariate analysis. In subgroup analysis, association of SO with OS was more prominent in patients with (y)p stage 0-2 and no inflammatory status.ConclusionThe presence of SO and a low body mass index at diagnosis are negatively associated with OS in non-metastatic rectal cancer patients.