Oncologic oUTcomes of neoadjuvant chemotherapy for obSTructive colon cAncer after steNt decompression (OUTSTAND trial); A study protocol of multicenter non-inferiority randomized controlled trial

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Abstract Background For obstructive colon cancer, many studies have been conducted on the use of self-expandable metallic stents (SEMS) as a bridge to surgery (BTS). However, there are currently no available prospective data on the impact of bridging period and there is a lack of research on the effects of neoadjuvant chemotherapy during the bridging period. Objectives Patients who undergo successful SEMS placement for obstructive left-sided colon adenocarcinoma without metastases will be eligible for this study. Design This study is a multicenter, non-inferiority, randomized (1:1), open-label, controlled trial. Methods & analysis The patients assigned to the control group will undergo curative surgery within two weeks after successful SEMS placement. The patients assigned to the experimental group will undergo three cycles of neoadjuvant FOLFOX chemotherapy within two weeks after successful SEMS placement. Curative surgery will be performed within four weeks of the last administration of neoadjuvant FOLFOX. Circulating tumor DNA (ctDNA) will be collected at specific time points. Discussion The optimal time interval for SEMS placement as a BTS can significantly impact long-term oncologic outcomes. In this study, our goal is to identify the optimal time interval for SEMS placement as a BTS. Recently, there has been interest in applying neoadjuvant chemotherapy for locally advanced colon cancer. In the context of early treatment for tumor dissemination following SEMS placement, neoadjuvant chemotherapy may be beneficial for delayed surgery after SEMS placement as a BTS. The results of this trial will be an important reference for the application of neoadjuvant chemotherapy in locally advanced colon cancer. Additionally, researchers will investigate whether ctDNA can serve as a reliable indicator to guide decisions about the timing and type of subsequent treatment. Based on the results of this trial, a patient-tailored treatment strategy can be developed for obstructive colon cancer. Registration This study is registered on ClinicalTrials.gov Identifier: NCT04889820, registered on May 17, 2021 in clinicaltrials.gov; Protocol ID: XC21MIDI0004.