• Patient's signed informed consent.

• Patient's age ≥18 years at the time of signing the informed consent.

• Histologically confirmed adenocarcinoma of the colon or rectum.

• Resected (R0 or R1) and/or effectively treated metastases (all techniques allowed) of colorectal cancer within 3-10 weeks before randomization (earlier randomisation allowed if at least 3 weeks interval between intervention and treatment start is guaranteed) AND resected primary tumor (synchronous or metachronous). In cases of synchronous metastases the interval of 3-10 weeks might be calculated following the removal of the primary tumor if this intervention was the last to address all tumor lesions.

• Absence of significant active wound healing complications (if applicable) at randomization. Resolved wound healing complications after resection/ablation are acceptable for inclusion into the trial.

• No radiographic evidence of active metastatic disease at study entry in a CT and/or MRI scan not older than 10 weeks prior randomization. Pre-surgery/ablation images are eligible for the study if all lesions have been addressed in the interval.

• ECOG performance status 0-2.

• Adequate bone marrow, hepatic and renal organ function, defined by the following laboratory test results:

‣ Absolute neutrophil count \>= 1.5 x 109/L (1500/µL)

⁃ Hemoglobin ≥ 80 g/L (8 g/dL)

⁃ Platelet count ≥ 100 x109/L (100000/µL) without transfusion

⁃ Total serum bilirubin of ≤ 1.5 x upper limit of normal (ULN)

⁃ Aspartate aminotransferase (AST/GOT) ≤ 3.0 × ULN.

⁃ Calculated glomerular filtration rate (GFR) according to Cockcroft-Gault formula or according to MDRD ≥ 50 mL/min or serum creatinine ≤ 1.5 x ULN

• Patients without anticoagulation need to present with an INR \< 1.5 x ULN and PTT \< 1.5 x ULN. Patient with prophylactic or therapeutic anticoagulation are allowed into the trial.

⁃ Proficient fluorouracil metabolism as defined:

• Prior treatment with 5-FU or capecitabine without unusual toxicity or

∙ If tested, normal DPD deficiency test according to the standard of the study site or

∙ If tested, in patients with DPD deficiency test with a CPIC activity score of 1.0-1.5 fluoropyrimidine/capecitabine dosage should be reduced by 50%

⁃ For women of childbearing potential (WOCBP): negative pregnancy test within 14 days before randomization and agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods with a failure rate of \< 1% per year during the treatment period and for at least 9 months after the last dose of Oxaliplatin or for at least 6 months after the last dose of all other study treatment.

⁃ A woman is considered to be of childbearing potential if she is post-menarcheal, has not reached a postmenopausal state (≥ 12 continuous months of amenorrhea with no identified cause other than menopause), and has not undergone surgical sterilization (removal of ovaries and/or uterus). Examples of contraceptive methods with a failure rate of \< 1% per year include bilateral tubal ligation, male partner's sterilization, hormonal contraceptives that inhibit ovulation, hormone-releasing intrauterine devices, and copper intrauterine devices.

⁃ For men: With female partners of childbearing potential, men must remain abstinent or use a condom plus an additional contraceptive method that together result in a failure rate of \< 1% per year during the treatment period and for 6 months after the last dose of study treatment. Men must refrain from donating sperm during this same period.