Surgeons do not know whether telling obese cancer patients to lose weight before an operation helps or harms them. This study will track 100 patients with oesophageal, stomach, or colorectal cancer who have a BMI over 30, measuring their weight, body composition, diet, and quality of life from diagnosis until surgery. The problem is a dangerous gap in clinical guidance. Obese patients face more complex surgeries and higher complication rates, so doctors often recommend pre-operative weight loss. Yet these same cancers raise the risk of malnutrition and muscle loss, which can worsen recovery. No robust evidence exists to say whether intentional weight loss is beneficial or dangerous in this group. If this research succeeds, it will provide the first clear evidence to support or reject pre-operative weight management for obese cancer patients. That could change standard surgical preparation, helping clinicians decide whether to prescribe weight loss or focus on preserving muscle mass. The result would be fewer surgical complications, shorter hospital stays, and better patient wellbeing—savings for the NHS as well as patients.
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Research question: How does weight loss and changes in body composition during the pre-operative phase of treatment affect surgical outcomes for patients living with cancer and obesity? Background: Cancer patients who are living with obesity are more likely to require technically challenging surgical procedures and therefore are more likely to experience complications post-surgery. Patients with a BMI > 30 kg/m2 are often encouraged to lose weight prior to surgery. An expert consensus by The American Society for Clinical Oncology found there is currently insufficient evidence to determine whether intentional pre-operative weight loss is beneficial to patients. Additionally, patients with oesophago-gastric or colorectal cancer, are at an increased risk of malnutrition and losses in lean muscle mass, which may negatively impact recovery from surgery. Aims and Objectives: The aim of this research is to determine the impact of weight loss on surgical outcomes for individuals with obesity who are undergoing curative surgery for oesophago-gastric and colorectal cancer. The objectives will be to 1) determine the association between pre-operative changes in body weight and composition, and surgical treatment outcomes for patients with a BMI > 30 kg/m2, 2) determine whether intentional weight loss prior to surgery provides benefits to patients in terms of their self-reported quality of life 3) establish preliminary evidence to support recommendations for or against intentional weight management interventions prior to cancer surgery. Methods: This prospective observational study will assess changes in patient s anthropometrics, body weight and composition prior to surgery, alongside measures of their nutrition using Patient-Generated Subjective Global Assessment (PG-SGA) and the Oxford Food and Activity Behaviours (OxFAB) , quality of life using the European Quality of Life Five Dimensions (EQ-5D-5L) and weight management strategies. Each participant will attend two data collection sessions, the first being directly after their cancer diagnosis and the second being before their surgery date. The main outcomes will be pre-operative weight loss and body composition changes, surgical complications, operating time and approach, and length of hospital stay. Timelines for delivery: The first stage of this project will be devoted to study set up, including the recruitment of the research assistant, the co-development of study documents with patient and public involvement and submission of the ethics application to obtain Health Research Authority (HRA) for this study. It is anticipated that data collection will run from September 2025 until August 2026, or until the target participant sample size (n=100) have successfully completed the study. Anticipated Impact and Dissemination: The provision of evidence-based weight management recommendations, will ensure patients are optimised nutritionally ahead of their surgery, increasing their tolerance to cancer treatment, improving patient wellbeing and reducing healthcare resource use. Findings from this research will be presented at national and international conferences and will be submitted for publication in high impact academic journals. Findings will also be communicated to key stakeholders, including clinicians, dietitians, cancer rehabilitation practitioners through presentations and education sessions to inform best practice for patient care and to patients through focus groups to gain their perspectives on the implications of the findings.
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