Neoadjuvant Chemotherapy for Locally Advanced T4 Colon Cancer: A Nationwide Propensity-Score Matched Cohort Analysis.

Introduction:Neoadjuvant chemotherapy (CT) for locally advanced colon cancer (LACC) could potentially lead to tumor shrinkage, eradication of micrometastases, and prevention of tumor cell shedding during surgery. This retrospective study investigates the surgical and oncological outcomes of preoperative CT for LACC.Methods:Using the Netherlands Cancer Registry, data of patients with stage II or III colon cancer, diagnosed between 2008 and 2016 was collected. A propensity score matching (PSM; 1:2) was performed and compared patients with clinical tumor (cT) 4 colon cancer who were treated with neoadjuvant CT to patients with cT4 colon cancer treated with adjuvant CT (Fig. 1).Results:A total of 192 patients treated with neoadjuvant CT were compared to 1,954 patients that received adjuvant CT. After PSM, 149 patients in the neoadjuvant group were compared to 298 patients in the control group. No significant differences were found in baseline characteristics after PSM. After neoadjuvant CT, a significant response was observed in 13 (9%) patients with 5 (4%) patients showing a complete response. Complete resection margins (R0) were achieved in 77% in the neoadjuvant group versus 86% in the adjuvant treated group (p= 0.037). Significantly less tumor positive lymph nodes were found in the neoadjuvant group (median 0 vs. 2,p< 0.001). Major complication rates and 5-year overall survival did not differ between both groups (67-65%,p= 0.87).Conclusion:Neoadjuvant CT seems safe and feasible with similar long-term survival compared to patients who are treated with adjuvant CT.