Impact Of Adding Oxaliplatin To Fluoropyrimidines In The Adjuvant Colon Cancer: Experience In Ramon Y Cajal University Hospital

815 Background: The addition of oxaliplatin to fluorouracil and leucovorin as adjuvant therapy for patients with stage II and III colon cancer (CC) has been analyzed in two large, randomized trials, MOSAIC and C-07 trials. The updated results of these studies showed that the addition of oxaliplatin enhances overall survival by approximately 5% in patients with stage III disease but has no effect in patients with stage II disease. Methods: We retrospectively included patients with stage II and III CC that were operated between 2009 and 2014 in the Ramón y Cajal University Hospital from Madrid. We perform a multivariable Cox model analysis to estimate the benefit of the chemotherapy stratifying by oxaliplatin in each stage. The model was further adjusted by including the following confounders: ECOG-PS, number of removed nodes, perforation, obstruction, grade and age. Stata 13.1 was used to analyze the data. Results: 564 patients were identified (281 stage II and 283 stage III). 305 did not receive any chemotherapy, 61 received monotherapy with fluoropyrimidines (FP) and 198, FP and oxaliplatin. The median follow-up in the entire cohort was 49 months. Globally, adjuvant chemotherapy (either with FP alone or with the combination with oxaliplatin) showed no benefit in DFS (HR of 1.18 and 0.98, respectively). The benefit in OS was significant either for FP alone (HR: 0.46, p: 0.029) and for the combination treatment (HR: 0.41, p: 0.001). Patients with stage II treated with FP in monotherapy showed no benefit, neither in DFS nor OS (HR for DFS: 2.2, p: 0.1; HR for OS: 0.5, p: 0.22). The benefit was neither seen with the addition of oxaliplatin (HR for DFS: 2, p: 0.11; HR for OS: 0.85, p: 0.7). Stage III patients treated with FP presented a HR for DFS of 0.76 (p: 0.5) and a HR for OS of 0.42 (p: 0.087). The HR for DFS with oxaliplatin was 0.53 (p: 0.07). A significant improvement in OS was observed, with a HR of 0.22 (p < 0.001). Conclusions: The addition of oxaliplatin in the adjuvant treatment of stage III patients showed a trend towards improvement in DFS and a significant benefit in OS compared to not receiving chemotherapy. On the contrary, patients with stage II did not benefit from this treatment, neither in DFS nor OS.