In locally advanced rectal cancer the pathological complete response (pCR) to neoadjuvant chemoradiation therapy (nCRT) is associated with a favourable long-term prognosis. The identification of markers predictive of response to therapy would therefore optimise treatment by allowing personalised therapy. It has been shown that the genetic profile of the patient could influence the activation of the immune system in combination with chemoradiation therapy in targeting tumour cells. In addition, genetic features of molecular pathways correlated with response to chemoradiotherapy, may in turn affect the probability of a good response to treatment in these patients, but also the occurrence of adverse events. The main objective of the study is to define the role of genetic markers related to immune system activation and other molecular pathways in predicting the complete pathological response to preoperative chemoradiation therapy in patients with locally advanced rectal cancer.