AB028. SOH24AB_086. Evaluating the impact of sarcopenia on oncological and survival outcomes in patients with locally advanced breast cancer

Background: Sarcopenia has been associated with negative clinical outcomes in several cancers, however its prevalence and impact on outcomes in patients being treated for locally advanced breast cancer (LABC) are yet to be determined. We assessed the impact of sarcopenia on outcomes in LABC. Methods: Consecutive female patients with LABC indicated to undergo neoadjuvant therapy (NAT) and surgery between 2010–2015 were included. Skeletal muscle index (SMI) and lean body mass (LBM) were determined. Sarcopenia was defined using computed tomography (CT) at L3 as SMI <38.5 cm2/m2. Thereafter, multivariable linear, logistic, and Cox regression analysis was undertaken to determine the independent impact of sarcopenia on outcomes. Results: Among 258 patients, the prevalence of sarcopenia was 23.0%, 7.8% and 0.0% of patients with normal weight, overweight and obesity, respectively (P=0.001). Sarcopenia was not associated with cT and cN stage, tumour grade, histologic type or receptor status. Moreover, sarcopenia was not associated with tumour sensitivity to NAT (i.e., ypT and ypN stage, pathologic complete response, and Sataloff grade). Postoperatively, sarcopenia did not independently predict with comprehensive complications index (P=0.242), length of stay (P=0.716) or overall morbidity (P=0.365). However, on multivariable analysis, lower LBM independently predicted reduced invasive disease-free survival (iDFS) [hazard ratio (HR): 0.93, 95% confidence interval (CI): 0.87–1.00, P=0.049] and overall survival (OS) (HR: 0.92, 95% CI: 0.85–0.99, P=0.028), but not disease-specific survival (DSS) (P=0.070). Conclusions: Sarcopenia was not associated with clinicopathological parameters or tumour response to NAT, however, reduced LBM independently predicted OS, but not DSS, in LABC. These data suggest that the prognostic impact of sarcopenia may be largely mediated by impaired performance status and increased non-cancer mortality.