Short RT Versus RCT,Followed by Chemo and Organ Preservation for Interm and High-risk Rectal Cancer Patients

The hereby proposed ACO/ARO/AIO-18.1 randomized trial aims to directly compare the newly established TNT concepts applying either short-course RT according to RAPIDO, or CRT according to CAO/ARO/AIO-04/-12, both followed by consolidation chemotherapy, and surgery or a watch\&wait (W\&W) approach for patients with clinical complete response (cCR). The ACO/ARO/AIO-18.1 study incorporates several novel and innovative aspects to further optimize multimodal rectal cancer treatment, partly established by our preceding CAO/ARO/AIO-04 and CAO/ARO/AIO-12 randomized trials: (1) patient selection is based on strict, quality controlled MRI features of intermediate and high-risk characteristics (and, thus, complementary to our ACO/ARO/AIO-18.2 trial in "low-risk" rectal cancer), (2) the CRT regimens incorporates 5-FU/oxaliplatin with doses and intensities shown to be effective and well-tolerated without compromising treatment compliance in CAO/ARO/AIO-04, (3) the sequence of CRT, CT, and surgery/W\&W adopts the TNT approach as established by our CAO/ARO/AIO-12 and OPRA trial, (4) surgical stratification allows for W\&W management for strictly selected patients with clinical complete response (cCR). Thus, we hypothesize that TNT with 5-FU/oxaliplatin-CRT followed by consolidation chemotherapy may increase organ preservation while maintaining DFS as compared to RAPIDO-like short-course RT followed by consolidation chemotherapy.