The investigators plan to measure the changes of health-related quality of life (HRQoL) at 6 months and 12 months after the following high-risk oncological abdominal surgery: gastrectomy, esophagectomy, pancreatectomy and hepatectomy. The investigators will measure the HRQoL using the validated EORTC QLQ-C30 questionnaire before and at 6 months and 12 month after the surgery. The investigators will identify phenotypes of HRQoL changes (improvement, stability and deterioration) at 6 months and 12 months after surgery. The second aim is to assess the regret of the patient at 6 months and 12 months regarding his/her decision to undergo surgery. The investigators will also assess the regret of the next of kin at 6 months regarding the decision to undergo surgery. This descriptive, prospective, observational, single-centre cohort study aims to: identify phenotypes of HRQoL changes after abdominal surgical oncology (improvement, stability and deterioration); assess the regret of patients regarding their decision to undergo surgical oncology at 6 months and 12 months; assess the regret of the next of kin regarding the decision of the patient to undergo surgical oncology at 6 months and 12 months. The investigators will include patients scheduled for the following elective abdominal cancer surgery: gastrectomy; esophagectomy; pancreas resection and hepatectomy. The investigators will assess HRQoL using the validated EORTC QLQ-C30 Summary Score before and 6 months and 12 months after surgery. The cut-offs for the three phenotypes of HRQoL changes will be defined using the minimal clinically important difference (MCID) of 10 points. The investigators will assess regret using the Decision Regret Scale (DRS) at 6 months and 12 months after surgery. The expected results are: The investigators can identify phenotypes of HRQoL changes after surgical oncology using the EORTC QLQ-C30 Summary Score; the investigators will describe the distribution of these phenotypes and will find an association with the pre-existing frailty. The investigators can describe the extent of the regret of the patient and of the next of kin at 6 months using the DRS. The investigators will observe an association between the DRS score at 6 months and the HRQoL Summary Score change. The investigators will not observe a relationship between the DRS score of patients and next-of-kins.