Benefit of adjuvant chemotherapy in patients with high-risk UICC II colon cancer T4N0M0: A ten-year population-based analysis of 3544 cases.

Abstract

628 Background: The benefit of adjuvant chemotherapy in UICC stage III colon carcinoma has been demonstrated in numerous studies. For UICC stage II such an advantage was not shown. However, it remains controversial whether adjuvant chemotherapy might be considered in certain high-risk UICC stage II situations. High-risk factors include T4 tumors, associated with an increased risk of recurrence and poorer prognosis due to their more aggressive biological behavior. Methods: The present population-based, multicenter cohort study investigated the influence of adjuvant chemotherapy on survival and recurrence rates in UICC stage II in the high-risk situation T4N0M0. It is based on an anonymized nationwide ADT dataset and includes 208,030 patients diagnosed with colorectal cancer from 2002 to 2011. A total of 3544 patients with a T4 tumor were identified, of whom 34.3% (1215 patients) received adjuvant chemotherapy and 65.7% (2329 patients) none. Results: Median overall survival was markedly prolonged in subjects who received adjuvant chemotherapy from 4.5 years (SD 0.163, 95% CI 4.1-4.8) to 8.1 years (SD 0.474, 95% CI 7.2 -9.0; p < .001). After 5 years, 69.5% of chemotherapy patients were still alive compared to 45.1% of non-chemotherapy patients. After adjusting for factors in a multivariable Cox regression analysis, the significant benefit of adjuvant chemotherapy for overall survival was maintained (HR = 0.642, 95% CI 0.555-0.743, p < .001). The relative cumulative risk of recurrence in the multivariable analysis was HR = 0.696 (95% CI 0.580-0.843, p < .001) for chemotherapy patients. Furthermore, a highly significant improvement in relapse-free survival through chemotherapy was demonstrated (HR = 0.634, 95% CI 0.555-0.725, p < .001). Conclusions: In this representative study, a significant advantage of adjuvant chemotherapy for UICC stage II colon carcinoma patients with a T4 tumor was demonstrated in terms of overall survival, recurrence rate and relapse-free survival. On the basis of these results, adjuvant chemotherapy is recommended for the high-risk situation T4.