Background: Weight loss in cancer is increasingly recognised as part of syndrome associated with chronic activation of the systemic inflammatory response (McMillan DC, 2009). The aim of the present study was to examine the relationship between systemic inflammation based prognostic scores (SIBPS) and CT measured parameters of body composition in patients with primary operable colorectal cancer (CRC). Methods: 303 patients with primary operable CRC who underwent resection with curative intent (2003-2012) were studied. Image analysis of CT scans was used to measure total fat index (cm²/m²), subcutaneous fat index (cm²/m²), visceral fat index (cm²/m²) and skeletal muscle index (cm²/m²). SIBPS included the Glasgow Prognostic Score (mGPS), Neutrophil: Lymphocyte ratio (NLR), Platelet: Lymphocyte Ratio (PLR), Prognostic Index (PI), and Prognostic Nutritional Index (PNI). Results: In all patients there was a significant association between lower BMI and skeletal muscle index and an elevated systemic inflammatory response, as measured by the mGPS (p=0.028 and p<0.001), NLR (p=0.004 and p=0.002), and PNI (p=0.001 and p=0.022). In male patients there was a significant association between lower BMI, total fat mass and skeletal muscle index and an elevated systemic inflammatory response, as measured by the mGPS (p= 0.027, p=0.048 and p=0.001), NLR (p=0.002, p=0.034 and p=0.003), and PNI (p=0.003, p<0.001 and p0.048). In female patients total body fat was associated with the PLR (p=0.001) and PNI (p=0.009) but only the mGPS (p=0.007) and the PI (p=0.013) were associated with reduced skeletal muscle. Conclusions: The present study highlights a consistent association between lower BMI and skeletal muscle mass and the presence of a systemic inflammatory response. These results are consistent with the hypothesis that chronic activation of the systemic inflammatory response results in the loss of lean tissue and that ultimately compromises survival in patients with CRC. McMillan DC. Systemic inflammation, nutritional status and survival in patients with cancer. Curr Opin Clin Nutr Metab Care. 2009;12:223-6.