Patients with colorectal cancer (CRC) often exhibit changes in body composition (BC) which are associated with poorer clinical outcomes. Many studies group colon and rectal cancers together, irrespective of staging, potentially affecting assessment and treatment strategies. Our study aimed to compare BC in patients with CRC focusing on tumor location and metastasis presence. A total of 635 individuals were evaluated, with a mean age of 61.8 ± 12.4 years and 50.2% female. The majority had rectal cancer as the primary cancer site (51.0%), and 23.6% had metastatic disease. The first regression model showed tumor site and metastasis as independent factors influencing skeletal muscle (SM), skeletal muscle index (SMI), and visceral adipose tissue variability (all p values < 0.05). The second model, adjusted for BMI, indicated tumor site as the primary factor affecting SMI variations (adjusted R² = 0.50 p < 0.001), with colon tumors inversely associated with SM (standardized β − 2.15(− 3.3; − 0.9) p < 0.001). A third model, considering all the confounders from the directed acyclic graphs, was constructed and the found association remained independent. Our findings highlight significant BC variations in patients with CRC, influenced by tumor location and metastases presence, underscoring the need for location-specific assessment in CRC management.

结直肠癌 (CRC) 患者经常表现出身体成分 (BC) 的变化，这与较差的临床结果相关。许多研究将结肠癌和直肠癌归为一类，而不考虑分期，这可能会影响评估和治疗策略。我们的研究旨在比较 CRC 患者的 BC，重点关注肿瘤位置和转移情况。共有 635 人接受了评估，平均年龄为 61.8 ± 12.4 岁，其中 50.2% 为女性。大多数人以直肠癌为原发癌部位（51.0%），23.6%有转移性疾病。第一个回归模型显示肿瘤部位和转移是影响骨骼肌（SM）、骨骼肌指数（SMI）和内脏脂肪组织变异性的独立因素（所有p值<0.05）。第二个模型根据 BMI 进行调整，表明肿瘤部位是影响 SMI 变化的主要因素（调整后的 R ²  = 0.50 p  < 0.001），结肠肿瘤与 SM 呈负相关（标准化 β − 2.15(− 3.3; − 0.9) p  < 0.001）。构建了第三个模型，考虑了有向无环图中的所有混杂因素，并且发现的关联保持独立。我们的研究结果强调了 CRC 患者的 BC 差异，受肿瘤位置和转移存在的影响，强调了在 CRC 管理中进行特定部位评估的必要性。