Indication for and effect of adjuvant chemotherapy for stage IIa (T3N0M0) colon cancer

Purpose: The efficacy of adjuvant chemotherapy (AC) in stage IIa colon cancer is controversial. This study aimed to investigate the factors influencing survival in patients with stage IIa colon cancer, the role of AC, and the indications for AC utilization by surgical oncologists. Methods: Between January 2004 and December 2010, 736 patients with stage IIa colon cancer underwent curative resection in 1 of 6 participating hospitals. Factors related to survival were identified and analyzed according to whether AC was administered or not. After high- A nd low-risk groups were identified, their respective results were analyzed. Results: The 5-year overall survival (OS) of stage IIa colon cancer was 90.3%. With the exception of poorly differentiated histology, indications for AC did not include typical high-risk factors. The indications for AC were significantly younger patients, higher body mass index (BMI), lower American Society of Anesthesiologists (ASA) physical status classification, and higher histologic grade. BMI, preoperative carcinoembryonic antigen, and harvested lymph node (LN) count were significant factors for disease-free survival, while BMI and ASA physical status classification were significant factors for OS in the chemotherapy group. In the high-risk group, AC was associated with increased OS in univariate analysis. BMI and harvested LN count were statistically significant in multivariate analysis. Conclusion: Surgical oncologists consider the patient's condition and postoperative course rather than high-risk factors to determine use of AC. Regardless of AC use, both the extent of surgery and the patient's subsequent status affected the survival rate in the high-risk group. None of the factors identified influenced survival rate in the low-risk group.