Chemoradiation and Consolidation Chemotherapy With or Without Oxaliplatin for Distal Rectal Cancer and Watch and Wait

Background: Neoadjuvant chemoradiation (nCRT) has been considered the preferred initial treatment strategy for distal rectal cancer. Advantages of this approach include improved local control after radical surgery but also the opportunity for organ preserving strategies (Watch and Wait - WW). Consolidation chemotherapy (cCT) regimens using fluoropyrimidine-based with or without oxaliplatin following nCRT have demonstrated to increase complete response and organ preservation rates among these patients. However, the benefit of adding oxaliplatin to cCt compared to fluoropyrimidine alone regimens in terms of primary tumor response remains unclear. Since oxaliplatin-treatment may be associated with considerable toxicity, it becomes imperative to understand the benefit of its incorporation into standard cCT regimens in terms of primary tumor response. The aim of the present trial is to compare the outcomes of 2 different cCT regimens following nCRT (fluoropyrimidine-alone versus fluoropyrimidine+oxaliplatin) for patients with distal rectal cancer. Methods: In this multi-centre study, patients with magnetic resonance-defined distal rectal tumors will be randomized on a 1:1 ratio to receive long-course chemoradiation (54Gy) followed by cCT with fluoropyrimidine alone versus fluoropyrimidine+oxaliplatin. Magnetic resonance (MR) will be analyzed centrally prior to patient inclusion and randomization. mrT2-3N0-1 tumor located no more than 1cm above the anorectal ring determined by sagittal views on MR will be eligible for the study. Tumor response will be assessed after 12 weeks from radiotherapy (RT) completion. Patients with clinical complete response (clinical, endoscopic and radiological) will be enrolled in an organ-preservation program (WW). The primary endpoint of this trial is decision to organ-preservation surveillance (WW) at 18 weeks from RT completion. Discussion: Long-course nCRT with cCT is associated with improved complete response rates and may be a very attractive alternative to increase the chances for organ-preservation strategies. Fluoropyrimidine-based cCT with or without oxaliplatin has never been investigated in the setting of a randomized trial to compare clinical response rates and the possibility of organ-preservation. The outcomes of this study may significantly impact clinical practice of patients with distal rectal cancer interested in organ-preservation.

Sex

All

Minimum age

18 Years

Inclusion Criteria:

1. Age ≥18 years;
2. ECOG 0-2 or KPS≥70;
3. Primary rectal adenocarcinoma (biopsy confirmed) within the reach of digital rectal examination (at least lower tip/border) by the attending colorectal surgeon;
4. Endoscopic documentation;
5. Abdominal and chest CT scans showing no evidence of metastatic disease;
6. High-resolution magnetic resonance images performed at either 1.5T or 3.0T system using a phased array surface coil with: sagittal T2 images including the anal verge and the sacrum; axial oblique T2 weighted images acquired in a plane perpendicular to the long axis of the rectal wall guided by the sagittal images; coronal images acquired in parallel to the anal canal plane. Small field of view (16-18cm), 3mm section thickness, increased matrix size and increased number of signal averages are required;
7. Radiological defining criteria (centralized):

   1. Lower edge of tumor at the level (max. 1cm distance) or below the anorectal ring defined at sagittal or coronal views;
   2. mrT2, mrT3 (any subclassification)
   3. mrN0-1 (≤3 radiologically positive lymph nodes)
   4. mrEMVI: any status
   5. mrMRF: any status

Exclusion Criteria:

1. Pregnancy
2. ECOG ≥3 or KPS\<70
3. Unwilling to consent
4. Metastatic disease (any kind; internal iliac and obturator nodes are considered local disease and not metastatic disease and therefore will not be considered as exclusion criteria)
5. mrT4 or mrN2
6. Previous pelvic irradiation
7. Baseline neuropathy
8. Receiving treatment of other anti-cancer drug or methods
9. Presence of uncontrolled life threatening diseases

• DERIVEDHabr-Gama A, Sao Juliao GP, Ortega CD, Vailati BB, Araujo S, Jorge T, Sabbaga J, Rossi GL, D'Alpino R, Kater FR, Aguilar PB, Mattacheo A, Perez RO; Latin American Rectal Cancer Consortium (LARCC). A multi-centre randomized controlled trial investigating Consolidation Chemotherapy with and without oxaliplatin in distal rectal cancer and Watch & Wait. BMC Cancer. 2023 Jun 14;23(1):546. doi: 10.1186/s12885-023-10984-2. PMID 37316784