Supplementary Material for: Pathologic Outcomes and Survival in Patients with Rectal Cancer and Increased Body Mass Index

Introduction: We assessed any association between increased body mass index (BMI) and rectal cancer outcomes.
Methods: We included patients who underwent surgery for stage I-III rectal adenocarcinoma who were divided according to BMI at diagnosis: ideal BMI (18.5-24.9 kg/m2) and increased BMI (≥25 kg/m2). Groups were compared using univariate association analyses relative to baseline characteristics, pathologic outcomes, overall survival (OS) and disease-free survival (DFS). Main outcome measures involved circumferential resection margin (CRM), pathologic TNM stage, total mesorectal incision (TME) grade, OS, and DFS.
Results: 243 patients (64.6% male; median age 59 years) with median BMI of 26.3 kg/m2 were included. 62.1% had BMI ≥25 kg/m2. Increased BMI patients had similar proportions of males (66.9% vs 60.9%;p=0.407) and comorbidities (ASA III: 47% vs 37.4%;p=0.24) to ideal BMI patients. There were no significant differences in cN1-2 stage (p=0.279) or positive CRM (p=0.062) rates. The groups had similar complete/near-complete TME, pathologic TN stage, and survival rates. Pathologic and survival outcomes were also similar with a BMI cutoff of 30.
Conclusions: There was a trend toward more nodal involvement in preoperative assessment and less CRM involvement in the final pathology of increased BMI patients. Complete/near-complete TME and survival rates were comparable between the groups.

引言：本研究旨在探讨体重指数（BMI）升高与直肠癌预后之间的潜在关联。
方法：本研究纳入了接受Ⅰ~Ⅲ期直肠腺癌手术治疗的患者，根据诊断时的体重指数分为两组：理想体重指数组（18.5~24.9 kg/m²）与体重指数升高组（≥25 kg/m²）。采用单变量关联分析，对比两组患者的基线特征、病理结局、总生存期（OS）及无病生存期（DFS）。主要结局指标包括环周切缘（CRM）、病理TNM分期、全直肠系膜切除（TME）分级、总生存期及无病生存期。
结果：本研究共纳入243例患者，其中男性占比64.6%，中位年龄59岁，中位BMI为26.3 kg/m²。62.1%的患者BMI≥25 kg/m²。与理想体重指数组患者相比，体重指数升高组的男性占比（66.9% vs 60.9%；p=0.407）及合并症情况（美国麻醉医师协会Ⅲ级：47% vs 37.4%；p=0.24）均无显著统计学差异。临床N1-2分期比例（p=0.279）及环周切缘阳性率（p=0.062）亦无显著差异。两组患者的全直肠系膜切除完整/近完整率、病理TN分期及生存率均无显著差异。当BMI截断值设为30时，病理结局与生存结局仍无显著差异。
结论：体重指数升高组患者在术前评估中存在淋巴结受累更多的趋势，而最终病理标本的环周切缘受累率则更低。两组患者的全直肠系膜切除完整/近完整率及生存率均无显著差异。