85P - Which is the best partner for capecitabine-based neoadjuvant chemoradiotherapy in locally advanced rectal cancer? A retrospective analysis of a comprehensive cancer center

Abstract

BackgroundThe purpose of this study was to compare the oncological outcomes of three preoperative chemotherapy regimens, capecitabine alone (Cap), capecitabine plus oxaliplatin (CapOx) and capecitabine plus irinotecan (CapIri), concurrent with long-course pelvic radiotherapy for patients with locally advanced rectal cancer (LARC) at a Chinese comprehensive cancer center. MethodsLARC (T3/4 and/or LN+) cases receiving neoadjuvant treatment between Mar 2006 and Feb 2018 were reviewed. Preoperative chemoradiotherapy consisted standard fractionated pelvic radiotherapy concurrently with chemotherapy of capecitabine alone, CapOx or CapIri. Total mesorectal excision was planned 6-10 weeks after the completion of chemoradiotherapy. Tumor response, neoadjuvant treatment toxicity and surgical complications of the three cohorts were compared analyzed. ResultsA total of 1165 patients were included in the study. 445 patients received concurrent capecitabine alone, 353 received CapOx and 367 received CapIri. An abdominoperineal resection or Hartmann’s procedure was performed in 46.4%, 59.8% and 47.2% of the patients who underwent surgery in the Cap, CapOx and CapIri cohorts, respectively (P = 0.001). The complete response (CR) rate (including pathological CR and clinical CR) was 20.7%, 18.7% and 28.6% in three cohorts (P = 0.003). Multivariate analysis showed that a lower tumor location, normal baseline CEA levels and the CapIri regimen were associated with a higher CR rate. Significantly more grade 3-4 toxicity was reported in the CapIri cohort than in the other two cohorts. Patients in the CapOx cohort were more likely to report surgical complications than the other patients (Cap vs CapOx vs CapIri: 13.4% vs 21.1% vs 13.3%, P = 0.005). ConclusionsConcurrent CapIri chemotherapy during preoperative pelvic radiotherapy significantly improved the CR rate but added toxicity compared with capecitabine alone or CapOx regimen. Long-term follow-up will determine if this short-term benefit translates into an improved survival. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.