Oncologic outcomes of pathologic T4 and T3 colon cancer patients diagnosed with clinical T4 stage disease using preoperative computed tomography scan.

BACKGROUND: The diagnostic accuracy of computed tomography (CT) for colon cancer is low, and the preoperative risk factors for locally advanced colon cancer are unknown. This study aimed to evaluate the correlation between preoperative CT scan findings and oncologic outcomes and to identify risk factors associated with locally advanced colon cancer. MATERIALS AND METHODS: Patients diagnosed with clinical stage (cT) 4 colon cancer based on preoperative CT scan findings who underwent curative surgery between January 2005 and December 2015 were retrospectively studied. Patients were divided according to pathologic stage (pT) into pT3 (n = 114) and pT4 (n = 102). RESULTS: The disease-free survival rate was significantly different between the pT3 and pT4 groups (88.6% vs. 68.6%, p < 0.001). The overall survival rate of the pT3 group was significantly higher than that of the pT4 group (91.2% vs. 76.5%, p = 0.002). Perineural invasion and tumor budding were identified as preoperative risk factors predisposing to pT4 staging (p = 0.044, p = 0.001). CONCLUSION: The survival rate of pT3 patients was significantly higher than that of pT4 patients with a preoperative cT4 diagnosis. This suggests that when planning for neoadjuvant chemotherapy in locally advanced colon cancer, preoperative CT scan findings may overestimate clinical staging and lead to inappropriate treatment. Thus, there is a need for a new modality to evaluate local advancement in colon cancer.