Translational Validation Study to Examine KFO179-1 Biomarker Scores for the Prediction and Prognosis of Advanced Primary Resectable Rectal Cancer Stages UICC-II-IV, With a 5-Fluorouracil-based Standard Radiochemotherapy Followed by Total Mesorectal Excision.

"Blood/biopsy samples (tumor \& mucosa) are taken pretherapeutically. Blood samples (serum \& plasma) are drawn at 11 time points during RCTx (e.g. for analysis of 5-FU metabolism, genomic DNA extraction). After pathohistological workup of the TME specimen, the formalin-fixed material will be transferred to the central biobank of KFO179. Blood samples (plasma \& serum) will be drawn during 5y-follow-up. Treatment (based on CAO/ARO/AIO-94- and CAO/ARO/AIO-04-phase-III trials of the GRCSG):~Preoperative RCT: 28x1.8 Gy (total: 50.4 Gy, 5 fractions per week on d1-d38) combined with 5-FU (1000 mg/m2/d) as 120 h civ during 1st and 5th week.~TME-surgery is performed 6 weeks after RCTx. 4 to 8 weeks after surgery, patients receive either 4 cycles 5-FU (500 mg 5-FU/m2 iv, d1-5, repeat d 29-33) or 3 cycles (6 single appl.) of FOLFOX regimen \[(400 mg FA/m2, 2-h civ, d 1; 100 mg oxaliplatin/m2, 2-h civ in 500 ml Glucose 5%, d 1; 2400 mg 5-FU/m2 as 46-h civ) on d1+d15, d30+d45 and d60+d75\]."