ACRNaCT trial protocol: efficacy of adjuvant chemotherapy in patients with clinical T3b/T4, N+ rectal Cancer undergoing Neoadjuvant Chemoradiotherapy: a pathology-oriented, prospective, multicenter, randomized, open-label, parallel group clinical trial

BACKGROUND: The CAO/ARO/AIO-94 demonstrated that neoadjuvant chemoradiotherapy (CRT) could decrease the rate of local recurrence rather than distal metastases in advanced rectal cancer. Adjuvant chemotherapy (ACT) can eliminate micrometastasis, and render a better prognosis to rectal cancer. However, adoption of ACT mainly depends on the evidence from colon cancer. Neoadjuvant CRT can lead to tumor shrinkage in a number of patients with advanced rectal cancer. The administration of adjuvant therapy depending on pretreatment clinical stage or postoperative yield pathological (yp) stage remains controversial. At present, the clinical guidelines recommend ACT for patients with stage II/III (ypT3–4 N0 or ypTanyN1–2) rectal cancer following neoadjuvant CRT and surgery. However, the yp stage may influence the guidance of ACT. METHODS: According to the postoperative pathological stage, the present study was divided into two parts with different study design procedures. Patients will undergo different therapeutic strategies after collecting data related to postoperative pathological stage. For patients with pathologic complete response or yp stage I, the study was designed as a non-inferiority trial to compare the patients’ long-term outcomes in observational group and those in treatment group with 5-fluorouracil. For patients at yp stage II or III, the study was designed as a superiority trial to compare the oncological effect of oxaliplatin combined with 5-fluorouracil, in addition to 5-fluorouracil alone in ACT. The primary endpoint is 3-year disease-free survival (DFS). Secondary endpoints are 3-year, 5-year overall survival, 5-year DFS, and the rate of local recurrence and adverse events resulted from chemotherapy and the patients’ quality of life postoperatively. DISCUSSION: The ACRNaCT trial aims to investigate whether observation is not inferior than 5-fluorouracil for pathologic complete response or yp stage I, and indicate whether combined chemotherapy contains superior outcomes than 5-fluorouracil alone for yp stage II or III in patients receiving neoadjuvant CRT and surgery for locally advanced rectal cancer (LARC). This trial is expected to provide individualized adjuvant treatment strategies for LARC patients following neoadjuvant CRT and surgery. TRIAL REGISTRATION: The trial has been registered in ClinicalTrials.gov on January 30, 2018 (Registration No. NCT03415763), and also, that was registered in Chinese Clinical Trial Registry on November 12, 2018 (Registration No. ChiCTR1800019445).