MEDAPO trial is a monocentric clinical trials with the use of human tissue in vitro. Because the lack of knowledge in literature about the increased degree of DNA methylation following acute administration of opioids in surgical patients, this study will be explorative. Moreover, not being able to avoid exposure to opiates in the intraoperative phase, but being possible to guarantee postoperative analgesia without opioid treatments, it will be interesting to see if any increase in methylation occurs already during the intraoperative phase or whether it can be related to the time of exposure to treatment with opiates.