BACKGROUND: In advanced gastric adenocarcinoma (aGC), the TAGS study demonstrated a survival advantage of trifluridine/tipiracil (FTD/TPI) over placebo in ≥3rd line setting. This led to approval in the United Kingdom (UK). Clinical trial and real-world patients often differ in age, fitness and comorbidity, which has implications for safety and survival. Real-world data can inform clinical practice. This study sought to define the UK patient population who have received FTD/TPI and compare outcomes to TAGS. METHODS: This was a retrospective study. Patients with aGC commenced on FTD/TPI prior to 1st February 2024 were eligible. Patients were identified from electronic health records. Data on baseline demographics and cancer outcome, including survival and toxicity, were collected. RESULTS: Data was collected for 58 patients from 12 centres in England, Scotland and Northern Ireland. Median age was 68.5 (range, 40-85) years, 44 (75.9%) were male and 10 (17.2%), 35 (60.3%) and 13 (22.4%) were Eastern Cooperative Oncology Group performance status (ECOG PS) 0, 1, and ≥2, respectively. Most primary tumours were gastroesophageal junctional (70.7%) and 24.1% were human epidermal growth factor receptor 2 (HER2) positive. FTD/TPI was given in 3rd line for 44 (75.9%) patients, 48 (82.8%) were commenced on full dose and on progression 6 (10.3%) received subsequent therapy. Median number of cycles received was 3 (range, 1-11). Median overall survival (mOS) in the whole population was 4.0 months [95% confidence interval (CI): 3.5-5.4], with mOS 5.9 vs. 4.0 vs. 2.5 months for ECOG PS 0, 1, and ≥2 respectively. On cox-regression analysis, with age, sex, ECOG PS, HER2 status, primary site and albumin as variables, ECOG PS ≥2 [hazard ratio (HR) =3.00; 95% CI: 1.07-8.35; P=0.04] and albumin ≥35 g/L (HR =0.47; 95% CI: 0.25-0.89; P=0.02) were prognostic; 29 (50%) and 16 (27.6%) patients required dose delay and reduction respectively, most commonly due to neutropenia. Grade ≥3 toxicity, attributed to FTD/TPI, was observed in 17 (29.3%) patients; 14 (82.4%) due to neutropenia and 3 (17.6%) anaemia. One (1.7%) patient stopped due to toxicity. CONCLUSIONS: We present UK real-world data regarding use of FTD/TPI for aGC. Compared to TAGS, the patient population differed and mOS was lower than the reported 5.7 months, but long-term survivors are observed. Pre-treatment ECOG PS and albumin appear prognostic. Toxicity is in line with that reported previously. Our data support the use of FTD/TPI in selected populations with aGC.