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.