CIRCULATE

Prior treatment

• Organ, stem cell or bone marrow transplantation
• Medication with brivudine, sorivudine or analogues in the last four weeks before planned treatment start.
• Known clinical high risk situation if it is regarded as certain in- dication for an adjuvant chemotherapy
• Participation at another interventional study for medical treat- ment during the last four weeks before randomisation
• Neoadjuvant therapy before resection
• Patients, in whom the randomisation or chemotherapy is un- feasible due to logistic reasons (travel distance, compliance)
• Women of childbearing potential and men with partner with childbearing potential who are not willing to take appropriate precautions to avoid pregnancy with a highly effective method in case they are randomised to “chemotherapy”
• Patients, in whom the randomisation or chemotherapy is un- feasible due to logistic reasons (travel distance, compliance)

Other illness

• Colon or rectal cancer with UICC stage III or IV
• Second cancer, except: simultaneous or metachronous colon or rectal cancer with UICC stage ≤ I, OR curatively treated basal cell carcinoma or squamous cell carcinoma of the skin and in-situ cervical carcinoma OR tumours with a disease free survival of more than five years
• Comorbidities relevantly interfering with the prognosis of the patients, i.e.: a) heart insufficiency NYHA III/IV b) relevant coronary heart disease, c) Diabetes mellitus with late sequelae
• Known hypersensitivity to capecitabine. In case of known hypersensitivity to oxaliplatin, the patients can participate, but not receive oxaliplatin.
• Acute infections
• Known HIV- infections, known active hepatitis B or C- infection

Lab values

• Contra indications for chemotherapy, especially: a) Leukocytes < 3,0 Gpt/l b) Neutrophil granulocytes < 1,5 Gpt/l c) Thrombocytes < 100 Gpt/l d) ALAT or ASAT > 3 x ULN e) Creatinine clearance (calculated according Cockcroft- Gault) < 30 ml/min

Age

• Patients, who have an obvious contra-indication for adjuvant chemotherapy (i.e. due to the performance status, comorbid- ity, active second cancer or age) It should be considered that patients with an age of more than 75 years frequently not fulfil criteria for adjuvant chemotherapy
• Age < 18 years

Other

• Patients with known microsatellite instability (MSI-H) or mis- match repair deficiency (dMMR)
• Known biallelic or homozygous dihydropyrimidine dehydro- genase (DPD)-deficiency
• R1- or R2- status. (Patients with [still] unknown R-status can be screened)
• Pregnant or breast feeding patients
• R1- or R2- status, or unknown R- status (Rx)
• Number of investigated lymph nodes < 10 5) WHO performance status ≥ 2

• Resected colon cancer stage II, OR Resected rectal cancer stage II, if there was no indication for radiotherapy (i.e. due to the localisation in the upper third of the rectum), so that the treatment follows the recommendations for colon cancer. Patients, in whom the tumour stage is not yet know, can be enrolled into the screening.
• Signed informed consent for the screening and the randomised phase
• Known microsatellite or mismatch repair status
• Confirmation, that the ctDNA result is available