Abstract 3036: Associations of total body fat mass and skeletal muscle index with all-cause and cancer-specific mortality in cancer survivors
Authors: Aduse-Poku Livingstone , Karanth Shama D. , Wheeler Meghann , Yang Danting , Washington Caretia , Fabregas Jesus , Cheng Ting-Yuan David , Braithwaite Dejana 
Published: April 2023

Abstract
Purpose of the Study: The purpose of the study was to investigate whether the risks of all-cause and cancer-specific mortality differ by levels of total fat mass and sarcopenia status in cancer survivors. Additionally, we conducted subgroup analysis to assess potential effect modification by race/ethnicity. The role of body composition in cancer outcomes is of great clinical interest, and measures of body composition that differentiate fat mass from skeletal muscle mass can help redefine our understanding of body composition for cancer survival.
Methods: Participants included 1682 adult cancer survivors who had undergone dual-energy x-ray absorptiometry (DXA) examination to measure body composition, gathered from the 1999-2006 and 2011-2018 National Health and Nutrition Examination Survey (NHANES). Total fat mass (weight of fat in the body) was categorized into tertiles (we assessed high vs. low tertiles), and sarcopenia was defined by appendicular skeletal muscle mass index (females &lt; 5.45kg/m2 and males &lt; 7.26kg/m2). Multivariable Cox proportional hazards models were performed to estimate adjusted hazard ratio (aHR) and 95% confidence interval (CI); we also stratified by race. In addition, we performed a restricted cubic spline analysis to assess the potential non-linear association between fat mass and all-cause mortality.
Results: The mean age of study participants was 61.9 years, and they were followed up for an average of 9.67 years. Overall, sarcopenia was present in 304 (25.0%), and 561 (33.4%) of the participants had high total fat mass. Participants with higher fat mass had 30% increased risk of all-cause mortality (aHR=1.30, 95% CI=1.06-1.61) compared to participants with low-fat mass, while participants with sarcopenia had a 51% higher risk (aHR=1.51, 95% CI=1.22-1.88) than participants with no sarcopenia. A restricted cubic spline analysis revealed a J-shaped association between fat mass and all-cause mortality. Further, sarcopenia was also associated with a higher risk of cancer-specific mortality (aHR=1.74, 95% CI=1.23-2.29) compared to non-sarcopenia. The association between sarcopenia and all-cause mortality was twice as strong in Non-Hispanic Blacks (aHR=2.99, 95% CI=1.39-6.06) compared to Non-Hispanic Whites (aHR=1.53, 95% CI=1.19-1.95).
Conclusion: Our findings show opposing relations of fat mass and appendicular skeletal muscle mass index with mortality in a national sample of cancer survivors, and the relationships may differ by race. These results emphasize the importance of maintaining a healthy body composition among cancer survivors.
Citation Format: Livingstone Aduse-Poku, Shama D. Karanth, Meghann Wheeler, Danting Yang, Caretia Washington, Jesus Fabregas, Ting-Yuan David Cheng, Dejana Braithwaite. Associations of total body fat mass and skeletal muscle index with all-cause and cancer-specific mortality in cancer survivors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3036.