The use of comprehensive geriatric assessment (CGA) in cancer patients older than 70 is recommended. Three pre-screening instruments have been proposed: the abbreviated comprehensive geriatric assessment (aCGA), the Vulnerable Elders Survey (VES-13), and the Groningen frailty index (GFI). The objective of the study was to identify the most efficient pre-screening tool that accurately determines individuals who may benefit from the entire CGA. A total of 113 elderly cancer patients were assessed by means of the aCGA, VES-13, GFI and the full CGA. The sensitivity, specificity of the three instruments was calculated, using the results from the entire CGA as the gold standard for the GFI and the VES-13. The aCGA was assessed whether each sub-component reliably predicts impairment on each sub-component of the full CGA. The majority of the participants were defined as being at risk of vulnerability: 68.14% had two or more impairments of the CGA or were cognitively impaired. The physical and disability questions are useful, but all other screening instruments miss too many cases. (C) 2009 Elsevier Ireland Ltd. All rights reserved.