OBJECTIVES: Admitting cancer patients to the ICU is associated with clinical and economic impacts. Therefore, the predictability if a cancer patient will benefit from ICU admission is essential. In this study, we aimed to evaluate the ability of health-related quality of life (QoL) prior to ICU admission measured using the EQ-5D-3L, to predict mortality in critically ill cancer patients. METHODS: This was a prospective cohort study of critically ill adult cancer patients in which caregivers were asked a set of questions, utilizing the EQ-5D-3L, to determine patients' QoL prior to ICU admission. The qualitative responses to the EQ-5D-3L were used to calculate the health utility summary measures using the time-trade-off value set for the UK population. To evaluate the predictive value of QoL prior to ICU admission, a receiver operator characteristic (ROC) curve was constructed and the area under the ROC (AUROC) was determined. The cutoff value of the utility score and the predictive values, sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated. A significance criterion of p<¼0.05 was used. RESULTS: The study included 140 critically ill cancer patients. Baseline QoL was associated with increased mortality (Odds ratio: 3.69; CI: 1.66-8.19; p ¼0.0014). The AUROC for mortality and utility scores prior to ICU admission was 0.6726 (CI,. The utility score of 0.2 was identified as the cut-off point that best predicts overall mortality with a sensitivity of 0.72, specificity of 0.64, PPV of 0.76, and NPV of 0.58. CONCLUSIONS: The quality of life prior to ICU admission, assessed utilizing the EQ-5D-LR, was a identified as a predictor of mortality in cancer patients treated in the ICU.