155 Long-Term Impact of Prophylactic Total Gastrectomy (PTG) in Patients with Hereditary Diffuse Gastric Cancer (HDGC) on Body Weight: Outcomes Within a Specialist Service

Abstract Introduction Definitive treatment for HDGC remains prophylactic total gastrectomy (PTG) but this carries significant nutritional consequences. Patients undergoing PTG do not have invasive cancer or undergo chemotherapy treatment which could confound weight changes. We aimed to study the long-term effect of PTG on weight. Method Weight changes were defined in patients undergoing PTG at a national referral centre between 2005 and 2025 and changes calculated relative to pre-operative baseline. Weight was measured pre-operatively and serially post-operatively using conventional and self-reported electronic methods. Follow-up included regular review by a multidisciplinary team including a specialist dietician and clinical interventions made as necessary. Results A total of 59 patients had pre-operative and serial post-operative weight measurements. Post-operative weight loss was universal at 3 months post-operatively but plateaued across all patients between 9 and 12 months at 20% absolute loss from baseline. A weight increase of 5% baseline weight was observed between 2 and 4 years post-op with a further weight plateau up to 10 post-operative years at 15% absolute weight loss across patients. In subgroups, the greatest magnitude of weight loss was seen in pre-operatively obese patients and maintained beyond 5 years. Conversely after initial weight loss, weight was regained in pre-operatively normal weight patients between 2 and 5 years post-operatively to reach pre-operative levels. Conclusions: Despite inevitable weight loss in the first 12 months post-PTG, weight regain is possible several years post-operatively within the context of a specialist multidisciplinary follow-up and nutritional support. Self-reporting using electronic tools provides promise for remote monitoring.