by Least Absolute Shrinkage and Selection Operator (Lasso) regression for Overall Survival (OS), OS<6 months and OS<12 months. OS prediction was quantified using Somers D XY statistic, which varies from 0 to 1, with increasing concordance between observed and predicted outcomes. 6-and 12 month survival were described by area under the curve (AUC) scores. Results Median OS was 270 (IQR 140-450) days. The primary OS model assigned high weights to 4 predictors: age, performance status, white cell

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... ount and serum albumin, and after cross-validation performed significantly better than would be expected by chance (mean D XY 0.332 (+/-0.019) figure 1). However, validation set D XY was only 0.221 (0.0935-0.346), equating to a 22% improvement in survival prediction than would be expected by chance. 6-and 12 month OS signatures included the same 4 predictors, in addition to epithelioid histology plus platelets and epithelioid histology plus C-reactive protein (mean AUC 0.758 (+/-0.022) and 0.737 (+/-0.012), respectively). The <6 month OS model demonstrated 74% sensitivity and 68% specificity. The <12 month OS model demonstrated 63% sensitivity and 79% specificity. Model content and performance were generally comparable with previous studies. Discussion The prognostic value of the basic clinical information contained in these, and previously published models, is fundamentally of limited value in accurately predicting MPM prognosis. The methods described are suitable for expansion using emerging predictors, including tumour genomics and volumetric staging. Abstract P243 Figure 1 Model performance as a function of the number of features for actual (red line) and permuted (blue line) data. Performance for Overall Survival (OS) is measured by D XY for OS. Standard deviations from replicates of cross-validation are shown for each point as bars.