Supplementary Material for: Left perforated colonic tumor with synchronous locally advanced right colonic tumor.

Colorectal cancer is one of the most common malignant neoplasms worldwide. Overall mortality is 33%. Synchronous colorectal cancer refers to more than one malignant tumor detected in different segments of the colon, simultaneously or within 6 months of initial diagnosis. The development of colorectal cancer is a multistep process that originates with a genetic mutation leading to a malignant phenotype and generating a growth advantage. Colorectal cancer presents up to 16% of hypermutations, of which 75% are characterized by microsatellite instability which in turn leads to poorer cell differentiation. Patients with synchronous tumors appear to have a higher proportion of microsatellite instability than patients with single tumors. It is presented the clinical case of a 35-year-old man with a perforated left colon tumor and a locally advanced synchronous tumor of the right colon and signs of acute abdomen. The treatment should be based on the location of the synchronous tumors, stage at the time of approach, and the patient's condition. However, when faced with a complication secondary to colonic cancer, adhering to the principles of oncological surgery can be overcome by the nature of the emergency.

结直肠癌（colorectal cancer）是全球范围内最常见的恶性肿瘤之一，总体死亡率达33%。同时性结直肠癌（synchronous colorectal cancer）指在结肠不同节段同时或初始诊断后6个月内检出的2处及以上恶性肿瘤。结直肠癌的发生为多步骤过程：始于基因突变，促使细胞获得恶性表型并获得生长优势。结直肠癌患者中高达16%存在高突变（hypermutations），其中75%以微卫星不稳定性（microsatellite instability）为特征，而微卫星不稳定性又会导致细胞分化程度降低。相较于单发肿瘤患者，同时性肿瘤患者的微卫星不稳定性检出比例更高。本文报告1例35岁男性患者的临床病例：该患者存在穿孔性左半结肠肿瘤、局部进展期右半结肠同时性肿瘤，并伴有急腹症征象。治疗方案应基于同时性肿瘤的位置、就诊时的分期以及患者整体状况制定。然而当面临结直肠癌继发的并发症急症时，急诊手术的特殊性可能会使得严格遵循肿瘤外科手术原则的要求难以落实。