Benefit of adjuvant chemotherapy in patients with T4, UICC II colon cancer.

Abstract

700 Background: Colorectal cancer is the third most common cancer and a major cause of morbidity and mortality worldwide. Adjuvant chemotherapy is considered standard of care in patients with UICC stage III colon cancer after R0-resection. For patients with UICC stage II colon cancer, a benefit of adjuvant therapy was not demonstrated. However, there is an ongoing discussion whether adjuvant chemotherapy may be beneficial for a subgroup of UICC II patients with "high-risk situation" (e.g., T4 situation). Methods: We investigated our Bavarian, population based (2.1 million inhabitants) cohort of 1,937 patients with UICC II CRC for a benefit of adjuvant chemotherapy in patients with larger (T4) tumors. Patients over 80 years were excluded. Of these patients, 240 patients had a T4 tumor (12%). 77 of all T4 patients received postoperative chemotherapy (33%). Survival analyses were performed using Kaplan Meier analysis and Cox regression models. Results: Patients with a T4 tumor who received postoperative chemotherapy had a highly significant survival benefit with respect to overall survival (p<0.001) and recurrence free survival (p=0.008). However, no difference was seen between oxaliplatin containing or non-oxaliplatin containing treatment regimens. Finally, G2 and G3 tumors were demonstrated to particularly benefit from adjuvant treatment. Chemotherapy, age at diagnosis and tumor grading remained independent risk factors in multivariable cox regression analysis. Conclusions: Overall, our retrospective study demonstrated a significant benefit of an adjuvant chemotherapy in the T4 UICC II subgroup of patients with colon cancer. Based on our data adjuvant chemotherapy should strongly be considered in these patients.