The recent distinction between co-morbidity and multi-morbidity well stresses the difficulty of managing old patients with cancer whose complexity is not captured by a list of diagnoses or biological burden alone. The most adequate answer found by oncologists and geriatricians was to work together for better evaluating the physiological age and body reserve of the patient. The gold standard tool to assess old patient with cancer is named Comprehensive Geriatric Assessment. Its systematic application needs geriatric competences and time. In this context, a great number of cancer patients are considered as "frail" because they have reduced available physiological reserves. They might not withstand stress when challenged. Oncologists and geriatricians have imagined an innovative process to change the screening procedure of these patients, determine the prognosis, adapt the treatment strategy, to increase the patient's survival and his/her quality of life. The internet website "www.clinicaltrials.com" only lists 8 studies focused on frail elders with cancer. Six of them are focused on specific cancers or specific treatments, one was applied to all kind of cancers and the last was an opinion overview from oncologists and geriatricians. The selection criteria of frail patients are very diverse and probably include cancer patients who are not comparable. It is now time to try to identify new practical, reliable and accurate tools to facilitate the inclusion of the same kind of patients suffering from the same kind of cancer to be able to give more appropriate care and at the same time to constitute a valuable data base. Existing tools are reviewed and analyzed.