Abstract 661: CT scan reveals that marked loss of muscle, visceral fat or subcutaneous fat after gastrectomy was a poor prognostic marker in advanced gastric cancer

Abstract

Abstract Background: There is increasing interest in the influence of body composition on oncologic outcomes. Using computed tomography (CT) scan, we evaluated the role of skeletal muscle and fat among patients with gastric cancer (GC) who underwent gastrectomy with or without adjuvant chemotherapy, as well as those changes' associations with survival outcomes. Methods: The present study evaluated 136 patients with GC who were enrolled in the CLASSIC trial at Yonsei Cancer Center. Baseline body compositions including skeletal muscle area, Hounsfield units (HU), visceral fat area, and subcutaneous fat area were measured by preoperative CT scan. The L3 region contains the psoas, paraspinal muscles, and abdominal muscles, which were quantified using the pre-established HU thresholds for skeletal muscle tissue (HU: -30~150). Visceral fat and subcutaneous fat areas (HU:-150~-30) were measured using axial slices at the level of the lumbar vertebra (L3). CT before and after the gastrectomy was used to determine the 6-month relative changes in body composition parameters. Continuous variables were dichotomized according to the best cut-off values by Contal and O'Quigley method. Results: Seventy-three patients (53.7%) underwent surgery alone, and 63 patients (46.3%) underwent surgery followed by adjuvant chemotherapy. The median baseline values were 46.8 cm2/m2 for SMI, 47.5 HU, 33.9 cm2/m2 for VFI, and 34.6 cm2/m2 for SFI. The baseline body composition parameters were not associated with disease-free survival (DFS) or overall survival (OS). However, patients with marked loss of skeletal muscle mass (<-11%), visceral fat area (<-48%), or subcutaneous fat (<-47%) after gastrectomy (the value was determined by best cut-off point) had poorer DFS and OS compared to patients with lesser changes. Patients with a marked loss in at least one significant body composition parameter had significantly shorter DFS (hazard ratio: 2.9, 95% confidence interval: 1.7-4.8, P<0.001) and OS (hazard ratio: 2.9, 95% confidence interval: 1.7-5.0, P<0.001). Conclusion: Marked loss in body composition parameters significantly predicted shorter DFS and OS among patients with GC who underwent gastrectomy. Postoperative nutrition and active health care interventions could improve the prognosis of these GC patients. CT data are readily obtainable during routine clinical practice, which makes this approach useful for identifying prognostic biomarkers. Citation Format: Si Won Lee, Hyung Soon Park, Seung Hoon Beom, Sun Young Rha, Woo Jin Hyung, Song-Ee Baek, Minkyu Jung. CT scan reveals that marked loss of muscle, visceral fat or subcutaneous fat after gastrectomy was a poor prognostic marker in advanced gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 661.