BACKGROUND: The prognostic assessment of older cancer patients is complicated by their heterogeneity. We aimed to assess the prognostic value of routine inflammatory biomarkers. METHODS: A pooled analysis of prospective multicenter cohorts of cancer patients aged >/=70 was performed. We measured CRP and albumin, and calculated Glasgow Prognostic Score (GPS) and CRP/albumin ratio. The GPS has three levels (0 = CRP </= 10 mg/L, albumin >/= 35 g/L, i.e., normal values; 1 = one abnormal value; 2 = two abnormal values). One-year mortality was assessed using Cox models. Discriminative power was assessed using Harrell's C index (C) and net reclassification improvement (NRI). RESULTS: Overall, 1800 patients were analyzed (mean age: 79 +/- 6; males: 62%; metastases: 38%). The GPS and CRP/albumin ratio were independently associated with mortality in patients not at risk of frailty (hazard ratio [95% confidence interval] = 4.48 [2.03-9.89] for GPS1, 11.64 [4.54-29.81] for GPS2, and 7.15 [3.22-15.90] for CRP/albumin ratio > 0.215) and in patients at risk of frailty (2.45 [1.79-3.34] for GPS1, 3.97 [2.93-5.37] for GPS2, and 2.81 [2.17-3.65] for CRP/albumin ratio > 0.215). The discriminative power of the baseline clinical model (C = 0.82 [0.80-0.83]) was increased by adding GPS (C = 0.84 [0.82-0.85]; NRI events (NRI+) = 10% [2-16]) and CRP/albumin ratio (C = 0.83 [0.82-0.85]; NRI+ = 14% [2-17]). CONCLUSIONS: Routine inflammatory biomarkers add prognostic value to clinical factors in older cancer patients.< Réduire