Clinical characteristics and oncologic outcomes in patients with preoperative clinical T3 and T4 colon cancer who were staged as pathologic T3

Purpose: Clinically suspected T4 stage colon cancer from a preoperative exam is often diagnosed as T3 stage colon cancer pathologically after surgery, raising concerns about understaging. The aims of this study were to compare the survival of clinical T3 and T4 colon cancer patients who had received a pathologic T3 stage diagnosis postoperatively. Methods: Patients who were diagnosed with pathologic T3 stage colon cancer postoperatively were reviewed. Patients with clinically suspected T3 or T4 stage cancer on preoperative exam were enrolled in the study. We compared patient demographics and survival of the cT3 and cT4 groups. Results: Out of the 536 patients with pT3 colon cancer, 503 patients were cT3 (93.8%) and 33 patients were cT4 (6.2%) preoperatively. The most common reason for suspected clinical T4 stage cancer was free perforation (78.8%). There were no statistically significant differences between the 5-year overall survival and the total 5-year disease-free survival (DFS) between the cT3 and cT4 groups; however, local recurrence was significantly higher in the cT4 group (local 5-year DFS: 98.6% vs. 84.0%, P < 0.001). Multivariate analysis showed cT stage was associated with local recurrence, but the association was not statistically significant (P = 0.056). Conclusion: Preoperative clinically suspected T4 stage colon cancer showed inferior local recurrence despite a postoperative pathologic diagnosis of T3 stage cancer, It is necessary to address the shortcomings of pathologic exams in the matter of the understaging of T4 colon cancer, and to reinforce the treatment for local control in patients with cT4 colon cancer.