Abstract 5951: Comparison of abdominal CT alone versus combined chest and abdominal CT on recurrence detection and mortality following gastrectomy for gastric cancer

Introduction: Recurrence patterns after gastrectomy for gastric cancer are diverse, with intraperitoneal recurrences being common and extraperitoneal also occurring. The optimal surveillance strategy remains unclear. This study examines the clinical significance of follow-up with abdominal CT (computed tomography) alone versus combined chest and abdominal CT. Methods: We analyzed data on surgery and follow-up CT scans for patients who underwent curative gastrectomy for gastric cancer between 2014 and 2018. The data were sourced from the Cancer Public Library Database, a nationwide public registry established under the Korean Clinical Data Utilization for Research Excellence Project (K-CURE). This newly launched registry is dedicated to research, providing comprehensive clinical data, including information on cancer diagnosis, surgery, summary staging, medications, diagnostic tests, comorbidities, and mortality. Patients were categorized into two groups based on surveillance CT patterns: those followed with abdominal CT alone (Group AA) and those with combined chest and abdominal CT (Group CA). Recurrence detection and all-cause mortality were compared between the groups. Considering variations in CT usage patterns over time, a time-varying Cox model was applied for group comparisons. The analysis was adjusted for key clinical factors, including age, sex, summary stage, co-morbidities, and hospital location. Results: Of the initial 69,090 patients, 50,813 were analyzed after excluding those with multiple primary cancers, missing, or unclear data. Among them, 44,488 were in Group AA and 6,325 in Group CA. Crude recurrence detection rate was higher in Group CA (13.17%, n=833) compared to Group AA (7.57%, n=3,368), and crude all-cause mortality was also higher in Group CA (21.47%, n=1,358) than Group AA (11.49%, n=5,110). Time-varying Cox regression analysis showed a significantly higher recurrence detection rate in Group CA (HR 1.21, 95% CI 1.12-1.30). Additionally, among patients with recurrence, Group CA was associated with a significantly lower mortality (HR 0.80, 95% CI 0.73-0.87) compared to Group AA. Subgroup analysis revealed higher recurrence detection rates in Group CA across all stages, with a significantly reduction in mortality among locally advanced-stage patients. Conclusions: This study demonstrated that combined chest and abdominal CT surveillance, compared to abdominal CT alone, improves recurrence detection regardless of stage and contributes to reduced mortality, particularly among patients with recurrent cancer at locally advanced stages. Prospective studies are warranted to establish an evidence-based surveillance strategy following gastrectomy. Citation Format: Chi Hoon Maeng, Yeonjin Kim, Hyun Ae Jung, Moon Ki Choi, Jung Yong Hong, Bo-Hyung Kim, Woojoo Lee. Comparison of abdominal CT alone versus combined chest and abdominal CT on recurrence detection and mortality following gastrectomy for gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5951.