PRELUDE-1 (Prospective Evaluation of Radiotherapy-induced Biologic Effects in Colorectal Cancer Oligometastatic Patients with LUng-limited Disease: Evolution of Cancer Genetics and Regulatory Immune Cells)

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