Abstract 2401: Changes in skeletal muscle mass after gastrointestinal cancer surgery by body composition

Abstract Background: Previous studies have extensively explored the correlation between preoperative skeletal muscle mass and long-term survival in gastrointestinal cancers. However, investigations into postoperative skeletal muscle mass alterations are limited. In gastrointestinal cancers, factors such as the tumor and surgical interventions can significantly impact dietary intake, nutritional status, and skeletal muscle mass, affecting postoperative body composition. This study aimed to examine these postoperative changes in skeletal muscle mass across different gastrointestinal cancers, including esophageal, gastric, and colorectum. Methods: This study encompassed 969 patients with Stage I-III esophageal (307 cases), gastric (278 cases), and colorectal (384 cases) cancers who underwent radical resection between 2005 and 2019. Skeletal muscle mass was quantified as the total psoas volume (TPV), measured using Ziostation2® imaging software from preoperative and postoperative CT scans at 1, 2, and 3 years. The study compared postoperative TPV trends across the different cancer types. Results: The study cohort comprised patients with esophageal (median age 66 years, 85% male), gastric (65 years, 60%), and colorectal cancers (67 years, 55%). Median BMIs were 21.5, 19.4, and 22.6 kg/m2, and median TPVs were 352.0, 305.8, and 309.5 cm3 for esophageal, gastric, and colorectal cancers, respectively. Esophageal cancer patients had significantly higher TPV and male predominance, while gastric cancer patients had notably lower BMI. Relative to preoperative TPV, the postoperative TPV at three years was 0.92, 0.91, and 0.96 for esophageal, gastric, and colorectal cancers, respectively. A year-by-year decrease in TPV was observed for each cancer type, with colorectal cancer demonstrating a less pronounced decrease compared to esophageal and gastric cancers (p<0.01). Stage-wise analysis revealed no significant differences among the cancer types. Regarding gender, no significant differences were noted between gastric and colorectal cancers, but esophageal cancer showed a more marked decrease in TPV in males compared to females. In recurrent cases, no significant TPV differences were observed in esophageal cancer, while recurrent gastric and colorectal cancers exhibited significant TPV decreases. Conclusions: The study indicates a general decline in TPV following gastrointestinal cancer surgery, with the extent of reduction varying according to the type of tumor and treatment. Citation Format: Yuto Maeda, Yuji Miyamoto, Mayuko Ohuchi, Yukiharu Hiyoshi, Naoya Yoshida, Hideo Baba. Changes in skeletal muscle mass after gastrointestinal cancer surgery by body composition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2401.