Purpose: The aim of this study was to identify indicators that can predict patients at high risk of tumor recurrence in Stage II, T3 colon cancer.
Methods: A total of 138 patients classified as Stage II, T3 underwent curative resection of colon cancer between 1981 and 1993. Clinical variables included age, gender, bowel obstruction, tumor location, and emergency presentation. For each colon tumor specimen, the following histopathological variables were assessed: maximum tumor diameter (<5 vs. >or=5 cm), depth, tumor grade (well and moderate vs. other), lymphatic and venous invasion (absent vs. present), perineural invasion, tumor necrosis, and tumor margin (expanding vs. infiltrating). We also categorized tumor budding, defined as a single cancer cell or small clusters of undifferentiated cancer cells in the invasive frontal lesion, into two categories: none or minimal (BD-1), and moderate or severe (BD-2). Univariate analysis for factors regarding recurrence and disease-specific survival were performed with the logistic regression model and the log-rank test.
Results: Among the factors analyzed, tumor budding was the only factor that was significantly associated with recurrence and survival. The numbers of patients with BD-1 and BD-2 tumors were 111 and 27, respectively. Forty-eight percent of BD-2 tumor patients developed recurrence, compared with 4.5 percent of BD-1 tumor patients (P < 0.0001). The cumulative disease-specific survival rates at five years for patients with BD-1 and BD-2 tumors were 98 and 74 percent, respectively (P < 0.0001).
Conclusion: The presence of moderate or severe budding at the invasive margin in Stage II, T3 colon cancer indicated a high risk of tumor recurrence after curative surgery, providing useful information for the decision regarding postoperative adjuvant chemotherapy.