A Comparison of Standard Neoadjuvant Long-Course Chemoradiotherapy and Near-Total Neoadjuvant Therapy in Rectal Cancer: A Matched Pair Analysis at Equal Time Interval

Abstract

<h3>Purpose/Objective(s)</h3> To investigate the efficacy of neoadjuvant chemotherapy administration following standard long-course chemoradiotherapy (LCCRT) before surgery (near-TNT), and to compare the outcomes with standard LCCRT in locally-advanced rectal cancer. <h3>Materials/Methods</h3> A total of 156 patients with cT3-4, cN0-2 rectal adenocarcinoma were included in this retrospective analysis, comprised of 79 patients treated with near-TNT, and 77 patients treated with LCCRT. Near-TNT defined as the incorporation of fluoropyrimidine plus oxaliplatin-based chemotherapy into the 12 weeks period between LCCRT and surgery. The patients treated with near-TNT and LCCRT were matched for cTNM stage at the same institution. The primary aim was to compare the pathologic complete response (pCR), and the secondary end-points were to compare the sphincter preservation and toxicity and safety of the treatments. <h3>Results</h3> A pCR was achieved in 40 of 156 patients (25.6 %) in the total population. The pCR were 24,1 % and 27,3 % with near-TNT and LCCRT, respectively (p=0,781). There was also no significant difference between near-TNT and LCCRT in term of sphincter preservation rate (65.8 % with near-TNT and 71.4 with LCCRT, p=0.561). The median tumor size was 2.5 cm (range: 0.2-10) after LCCRT, and 1.5 cm (range: 0.1-8) after near-TNT (p<0,001). Although near-TNT resulted in increased chemotherapy-related toxicity (p<0001), the treatment did not lead increased postoperative complications. When the groups compared with the Clavien-Dindo score, near-TNT group showed better postoperative complication rates (p=0,008). Additionally, near-TNT group exhibited better postoperative duration of hospitalization (p=0.002). <h3>Conclusion</h3> Though the addition of chemotherapy between the time interval of LCCRT and definitive surgery did not lead pCR rates, it might induce better tumor downsizing together with a cost of treatment-related toxicities. Besides downsizing effects, a positive postoperative complication rates make near-TNT as a potential treatment-approach in locally-advanced rectal cancer.