Supplementary Material for: Patient’s Skeletal Muscle Radiation Attenuation and Sarcopenic Obesity are Associated with Postoperative Morbidity after Neoadjuvant Chemoradiation and Resection for Rectal Cancer

Background/Aims: To investigate the relation between skeletal muscle measurements (muscle mass, radiation attenuation, and sarcopenic obesity), postoperative morbidity, and survival after treatment of locally advanced rectal cancer. Methods: This explorative retrospective study identified 99 consecutive patients who underwent neoadjuvant chemoradiation and surgery between January 2007 and May 2012. Skeletal muscle mass was measured as total psoas area and total abdominal muscle area (TAMA) at 3 anatomical levels using the patient’s preoperative computed tomography scan. Radiation attenuation was measured using corresponding mean Hounsfield units for TAMA. Sarcopenic obesity was defined as body mass index above 25 kg·m–2 combined with skeletal muscle mass index below the sex-specific median. Postoperative complications were graded by using the Clavien-Dindo classification. Results: Twenty-five patients (25.3%) developed a grade 3–5 complication. Lower radiation attenuation was independently associated with overall (p = 0.003) and grade 3–5 complications (p = 0.002). Sarcopenic obesity was associated with overall complications (all p < 0.05). Skeletal muscle measurements and survival were not significantly related. Conclusion: Radiation attenuation was associated with overall and grade 3–5 postoperative morbidity after neoadjuvant chemoradiation and non-laparoscopic resection for rectal cancer. Sarcopenic obesity was associated with overall complications.

背景与研究目的：探讨局部进展期直肠癌患者接受治疗后，骨骼肌测量指标（包括肌肉质量、放射衰减值与肌少症性肥胖（sarcopenic obesity））、术后并发症发生率与患者生存率之间的关联。
方法：本项探索性回顾性研究纳入2007年1月至2012年5月期间连续入组的99例接受新辅助放化疗（neoadjuvant chemoradiation）联合手术治疗的局部进展期直肠癌患者。通过患者术前计算机断层扫描（CT，computed tomography）图像，在3个解剖层面测量腰大肌总面积与腹部总肌肉面积（total abdominal muscle area, TAMA）以评估骨骼肌质量；通过腹部总肌肉面积对应的平均亨氏单位（Hounsfield units）测量放射衰减值。肌少症性肥胖定义为体质量指数（BMI，body mass index）≥25 kg·m⁻²，同时骨骼肌质量指数低于性别特异性中位数。术后并发症采用Clavien-Dindo分级系统进行评级。
结果：共计25例患者（占比25.3%）发生3~5级术后并发症。较低的放射衰减值与总体并发症（p=0.003）及3~5级并发症（p=0.002）独立相关。肌少症性肥胖与总体并发症存在显著关联（所有p值均<0.05）。骨骼肌测量指标与患者生存率无显著关联。
结论：直肠癌患者接受新辅助放化疗联合非腹腔镜手术切除治疗后，放射衰减值与总体术后并发症及3~5级术后并发症相关；肌少症性肥胖与总体术后并发症相关。