Summary Background & aims Estimation errors associated with bioelectric impedance evaluation may affect the accuracy of body composition and its prognostic value. We evaluated the prognostic value of a new body composition parameter (Nutrigram®) obtained from bioimpedance vectorial analysis-derived body cell mass and its association with nutritional and functional status. Design Data of Italian and German cancer patients observed prospectively until death were used. Multivariable models (adjusted for age, gender, hydration status, performance status, and disease's stage) were built in both cohorts to assess the association between body composition outcome parameters (low fat-free mass [FFM], Results Low Nutrigram® was independently associated with mortality in both Italian (HR = 1.84 [95%CI, 1.18–2.86]; P = 0.007) and German cohorts (HR = 1.52 [95%CI, 1.17–2.07]; P = 0.008). Low FFMI and low SPA did not predict survival in the German cohort. In patients with low Nutrigram®, worse nutritional and functional status were observed in both study populations. Performance of models addressing the study endpoints showed substantial consistency with both cohorts, particularly of those including low Nutrigram®. Conclusions We validated a new prognostic body composition parameter, which is easier to interpret than standard nutritional parameters and may be useful for identifying cancer patients at nutritional risk, requiring early nutritional support.