Inclusion Criteria:  Age <80 years Cytological or histological diagnosis of colorectal adenocarcinoma Two or three asymptomatic lung nodules smaller than 25 mm Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1 Available Formalin Fixed Paraffin Embedded (FFPE) of resected primary tumor Negative pregnancy test for all potentially childbearing women Patient candidates to SBRT  Exclusion Criteria:  Previous systemic anti-tumor treatments (allowed treatment with capecitabine or fluorouracil and radiotherapy in the neoadjuvant setting of rectal tumors with therapy terminated at least 6 months before) Neutrophils <2000/mm³ or platelets <100.000/mm³ or hemoglobin <9 g/dl; serum creatinine level> 1.5 times the maximum normal value; GOT and/or GPT >5 times the maximum normal value and/or bilirubin level >3 times the maximum normal value Previous or concomitant malignant neoplasms (excluding basal or spinocellular cutaneous carcinoma or in situ carcinoma of the uterine cervix) Active or uncontrolled infections Other concomitant uncontrolled diseases or conditions contraindicating the study drugs at clinician evaluation Presence of brain metastases Refusal or inability to provide informed consent Impossibility to guarantee follow-up