Introduction: Postoperative health-related quality of life (HRQoL) is an essential outcome in oncological surgery, particularly for elderly patients undergoing high-risk surgery. Previous studies have suggested that, on average, HRQoL returns to premorbid normal levels in the months following major surgery. However, the averaging of effect over a studied cohort may hide the variation of individual HRQoL changes. The proportions of patients who have a varied HRQoL response (stable, improvement, or a deterioration) after major oncological surgery is poorly understood. The study aims to describe the patterns of these HRQoL changes at 6 months after surgery, and to assess the patients and next-of-kin regret regarding the decision to undergo surgery.

Methods and analysis: This prospective observational cohort study is carried out at the University Hospitals of Geneva, Switzerland. We include patients over 18 years old undergoing gastrectomy, esophagectomy, pancreas resection or hepatectomy. The primary outcome is the proportion of patients in each group with changes in HRQoL (improvement, stability or deterioration) 6 months after surgery, using a validated minimal clinically important difference of 10 points in HRQoL. The secondary outcome is to assess whether patients and their next-of-kin may regret their decision to undergo surgery at 6 months. We measure the HRQoL using the EORTC QLQ-C30 questionnaire before and 6 months after surgery. We assess regret with the Decision Regret Scale (DRS) at 6 months after surgery. Key other perioperative data include preoperative and postoperative place of residence, preoperative anxiety and depression (HADS scale), preoperative disability (WHODAS V.2.0), preoperative frailty (Clinical Frailty Scale), preoperative cognitive function (Mini-Mental State Examination) and preoperative comorbidities. A follow-up at 12 months is planned.

Ethics and dissemination: The study was first approved by the Geneva Ethical Committee for Research (ID 2020-00536) on 28 April 2020. The results of this study will be presented at national and international scientific meetings, and publications will be submitted to an open-access peer-reviewed journal.

Trial registration number: NCT04444544.