Low and Intermediate Risk OliGometastatic ColoREctal CancEr PatieNts Treated with Stereotactic ABlative Radiotherapy

This is an experimental study without drug or device, randomized, open-label, non-profit, sponsored by the IRCCS Sacro Cuore Don Calabria Hospital in Negrar, which will take place at the Department of Advanced Oncological Radiotherapy and 18 other Italian centers. The reason for this research study is to evaluate whether stereotactic radiotherapy treatment (SABR), in addition to the systemic chemotherapy treatment foreseen by clinical practice for low-intermediate risk oligometastatic colorectal cancer, is able to: * delay possible local recurrence and/or distant polymetastatic progression * improve disease-free survival * reduce side effects in the short and long term thus inducing an improvement in the quality of life of patients suffering from this type of pathology. Therefore, as part of this randomized study, before starting first or second line systemic therapy for his tumor, the patient will be randomized to one of the following treatment arms: * Experimental arm: ablative stereotactic radiotherapy on all sites of oligometastatic disease (from 1 to 3 sites, performed at most within the second cycle of systemic therapy) * Control arm: no ablative stereotactic radiotherapy to sites of oligometastatic disease The procedure that is intended to be tested in the experimental arm is a stereotactic radiotherapy treatment on oligometastases (up to a maximum of 3 sites), with ablative dosage (effective biological dose \>100 Gy), performed before the start of systemic therapy of I or II line (at most within the second cycle of the same). It is hoped that the addition of this type of radiotherapy will increase the potential clinical benefit of the treatment in the context of colorectal cancer.