Background: There is a lack of appropriate information in regard to the optimal treatment for colon cancer infiltrating neighboring organs. Objectives: The objective of this study is to analyze treatment results and to identify the risk factors of death by cancer in these patients. Methods: A retrospective analysis of 40 patients with colon cancer infiltrating neighboring organs without distant metastases was carried out. Patterns of recurrence and 5-year survival were analyzed. Results: The study included 20 males and 20 females with a median age of 51.5 years. Primary tumor location was as follows: right colon (n = 15); transverse colon (n = 5); left colon (n = 7), and sigmoid (n = 13). In 17 patients, the colon tumor infiltrated the abdominal wall alone or together with neighboring organs and in 23 patients, one or more neighboring organs were infiltrated. Eleven patients (27.5%) developed postoperative complications. Two patients (5%) died during the postoperative period. Microscopic tumor infiltration was demonstrated in 29 patients (72.5%). Tumor stage was as follows: T3,NO (n = 8); T3,N+ (n = 3); T4,NO (n = 16), and T4,N+ (n = 13). Overall 5-year survival was 45%. Multivariate analysis shows that the unfavorable risk factors for 5-year survival were neoplastic cell infiltration to neighboring organs, age > 50 years, and lymph node metastases. Conclusions: The main risk factors for cancer-related failure are neoplastic infiltration to neighboring organs, age > 50 years, and lymph node metastases. In T4 colon cancer, the recurrence pattern was found at local, peritoneal, and distant sites. (C) 2002 Wiley-Liss, Inc.