Risk factors associated with ifosfamide (IFOS)-induced encephalopathy in patients (pts) with metastatic (Met) sarcoma (Sarc).
e22518 Background: IFOS is commonly used in the treatment of met sarc. IFOS has been reported to cause encephalopathy in 5 - 30% of pts. Potential risk factors for IFOS-induced encephalopathy (IIE) include female gender, older age, route of administration of IFOS, low serum albumin, existence of pelvic disease and renal failure. Unfortunately, the majority of the data surrounding potential risk factors is from heterogeneous cohorts. Methods: The purpose of this single-center retrospective analysis was to identify risk factors for developing IIE in a homogenous cohort of met sarc pts treated at MSKCC between 1/2010 and 5/2015. Logistic regression was used to examine the univariate effect of baseline and treatment variables. Variables significant at the 0.05 level were entered into a multivariate model. Results: A total of 328 met sarc pts with a median age of 51 years were analyzed. Thirty-four pts (10%) developed IIE. Of those 34 pts, 88% developed encephalopathy with the first or second cycle of IFOS. Age at the time of treatment (p = 0.0037), low serum albumin (p < 0.0001), increased serum alkaline phosphatase (p = 0.0022), liver met disease (p = 0.0011) and more than 3 met sites at time of IFOS dose (p = 0.0008) were all identified as risk factors by univariate analysis. Only low serum albumin (p < 0.0001, odds ratio = 0.33) and more than 3 met sites at time of IFOS dose (p = 0.0068, odds ratio = 2.47) maintained statistical significance after multivariate analysis. Conclusions: To our knowledge, this is the largest retrospective analysis of risk factors for IIE in the met sarc population. This analysis identified low serum albumin and more than 3 met sites at time of IFOS as predictors of IIE. Our data would suggest that clinicians considering the option of IFOS in met sarc pts should give particular attention to these predictive risk factors when making their treatment decisions.