1. School of Nursing, Midwifery and Social Work Malnutrition or poor body composition, particularly sarcopenia, may have a negative impact on clinical outcome [1]. Currently, there are minimal data on the roles of computed tomography (CT) & bioelectrical impedance analysis (BIA) in determining body composition, particularly in those with colorectal cancer. AIM: To measure fat free mass using both CT & BIA to identify sarcopenia or cachexia. Measuring fat free mass in people with colorectal cancer & weight loss. 1 School of Nursing Midwifery and Social Work, University of Manchester, UK 2 Salford Royal Foundation Trust, Manchester, UK Debra J. Gibson * 1, Sorrel Burden 1, Chris Todd 1, Boyd J. Strauss 2, Simon Lal 2 Included 43 patients (62.8% male); mean weight loss 7.8%(SD 6.2). 19 patients had pre op C-reactive protein (CRPs) recorded and 10 of these had raised levels. BIA identified a higher incidence of sarcopenia but a lower incidence of cachexia in comparison to CT. (Tables 1 & 2) BIA appears to underestimate fat free mass, compared to CT, and demonstrates increased sarcopenia incidence. Muscle area from CT shows a lower incidence of sarcopenia, compared to BIA, but identifies more individuals as cachectic. CT scans may offer a more reliable means of assessing body composition in colorectal cancer patients compared to BIA. Conclusion Body composition data Introduction Results Table 2. Identification of sarcopenia & cachexia from BIA and CT BIACTICC Sarcopenia n(%) [male : female] 22 (51.2%) a 15 (34.9%) b r =0.490 (p=0.016) [13 : 9][15 : 0] Cachexia n(%) [male : female] 2 (10.53%) c 3 (15.79%) c r =0.877 (p<0.001) [2 : 0][3 : 0] a Sarcopenia definition for BIA: sex-specific cut-offs of ≤17 kg/m 2 for males & ≤15 kg/m 2 for females, determined by Vermeeren [2] & endorsed by ESPEN [3] b Sarcopenia definition for CT: sex-specific cut-offs of <55cm 2 /m 2 for males & <39cm 2 /m 2 for females, determined by Mourtzakis [4] & endorsed by ESPEN [3] C Cachexia definition: Identified as sarcopenic with a weight loss of >2% and systemic inflammation (raised CRPs) [5] Method Preoperative weight losing people with colorectal cancer were recruited. Ethical approval was attained. Body composition was measured using single frequency BIA (Bodystat 1500 and CT slices (L3) analysed with SliceOmatic software (v5 Tomovision). BIA and CT were assessed for level of agreement in determination of sarcopenia and cachexia incidence. [1] Prado et al. Lancet Oncology, 2008;9(7). [2] Vermeeren et al. Respiratory medicine, 2006;100. [3] Biolo et al. Clinical Nutrition, 2014;33. [4] Mourtzakis et al. Applied Physiology, Nutrition and Medicine, 2008;33(5). [5] Fearon et al. Lancet Oncology, 2011;12. No. LB031- SUN Body composition via CT scan Table 1. Body composition measurements from BIA and CT MeanStandard deviation BIA fat free mass (kg)46.4713.25 BIA fat free mass index (kg/ht 2 )16.373.51 CT scan muscle area (cm 2 )150.6536.16 CT scan muscle area index (cm 2 /ht 2 )53.8211.30