Eligibility and inclusion criteria
tumor, Tumor, colorectal surgeon;Endoscopic, statusTumor, MR, colorectal surgeon
RECTAL ADENOCARCINOMA, TUMOR, INVASION, TUMOR
Patients will be eligible in the presence of the following inclusion criteria:Age ≥18 years;ECOG 0-2 or KPS≥70;Primary rectal adenocarcinoma (biopsy confirmed) within the reach of digital rectal examination (at least lower tip/border) by the attending colorectal surgeon;Endoscopic documentation of the primary tumor;Abdominal and chest computed tomography (CT) scans showing no evidence of metastatic disease;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;Radiological defining criteria (centralized):Lower edge of tumor at the level (max. 1cm distance) or below the anorectal ring defined at sagittal or coronal views;mrT2, mrT3 (any subclassification)mrN0-1 (≤3 radiologically positive lymph nodes)mr Extramural Vascular Invasion (EMVI): any statusmr Mesorectal Fascia (MRF): any statusTumor location (both criteria need to be met in all patients)*:Lower edge of tumor at the level (max. 1cm distance) or below the anorectal ring defined at sagittal or coronal views using magnetic resonance;Primary rectal adenocarcinoma (biopsy confirmed) within the reach of digital rectal examination (at least lower tip/border) by the attending colorectal surgeon* Tumor height will be defined by an objective and reproducible criteria (distance of the lower edge of the tumor from the insertion of the levator ani muscles – anorectal ring – determined on sagittal and/or coronal views from MR T2-weighted sequences). As MR images will be centrally reviewed and stored, this will provide an objective, reproducible and allow auditing of the data. Accessibility to the finger of the examining physician will NOT be used as a measure of height—instead, only used to provide homogeneity in tumor response assessment criteria for all patients included in the study.