Tumor extent impacts survival benefit in minimally invasive colectomy for T4 colon cancer: A propensity matched national cohort analysis.

BACKGROUND: T4 colon cancers have been underrepresented in randomized trials comparing minimally invasive colectomy (MC) versus open colectomy (OC). Retrospective studies suggest improved survival with MC versus OC, but have not addressed the impact of tumor extent. METHODS: Using the National Cancer Database (NCDB), we analyzed patients undergoing colectomy for T4 colon adenocarcinoma from 2010 to 2014. Propensity score matching was performed between MC and OC patients. Tumor extent was defined by zones based on adjacent organ involvement. RESULTS: Of the 19 178 eligible patients, 6564 (34%) underwent MC. After matching, MC was associated with improved overall survival (hazard ratios: 0.71, 95% confidence interval: 0.67-0.76; median OS 59 vs. 42 months, p < 0.001). Compared to MC patients, those undergoing OC had: a higher margin positive rate (p = 0.009); lower median nodes examined (p < 0.001); a lower rate of adjuvant chemotherapy (p < 0.001); and a longer median time to chemotherapy (p < 0.001). Stratified survival analyses demonstrated that MC was associated with improved overall survival compared to OC in all zones except zone 3 and 4. CONCLUSIONS: Compared to OC, MC for T4 colon cancer is associated with improved oncologic outcomes when performed for zone 0-2 tumors. For, zone 3 and 4 tumors MC and OC have similar oncologic outcomes and patients should be cautiously selected.