Recurrence risk factors and outcome stratification in stage II colon cancer patients: A subanalysis of the SACURA trial.

Abstract

3611 Background: Efficacy of adjuvant chemotherapy for stage II colon cancer is still controversial. We conducted the SACURA trial, a phase III study which evaluated the superiority of 1-year adjuvant treatment with oral tegafur-uracil (UFT) to surgery alone in stage II colon cancer. However, survival benefit of 1-year UFT to surgery alone was not demonstrated (ASCO2016 abst#3617). We herein aimed to identify risk factors for recurrence in the stage II patients “without adjuvant chemotherapy”, and to stratify the prognosis by using these factors. Methods: Among a total of 982 patients without adjuvant chemotherapy enrolled to the SACURA trial, we extracted the factors correlated to recurrence using a univariate and multivariate Cox proportional hazard model. 943 and 935 patients in the surgery alone group and UFT group were divided to subgroups according to the number of risk factors, and the recurrence rate in each subgroup was evaluated. Results: Among the conventional clinicopathological characteristics, the multivariate analysis identified pT4, elevated CEA, and examined lymph nodes less than 12 as significant risk factors for recurrence. The rate of patients with 0, 1, 2, and 3 risk factors were 45.0%, 42.4%, 11.5%, and 1.1%, respectively. The recurrence rate for each subgroup was shown in the table: the recurrence rate increased with number of risk factors, while 10.2% of patients without any risk factors developed recurrence. Difference in the recurrence rate between the treatment groups was significant in patients without risk factor, marginal in patients with 1 risk factor, and none in patients with >1 factors. Conclusions: pT4, elevated CEA, and examined lymph nodes less than 12 were identified as risk factors for recurrence in stage II colon cancer patients. The recurrence rate was divided by the number of these risk factors, but we could not extract the very-low risk group in whom adjuvant therapy is unnecessary. Induction of novel risk factors other than conventional clinicopathological characteristics is recommended. Clinical trial information: NCT00392899. [Table: see text]