Oncogeriatric frailty assessment is a multifactorial approach to determine the most appropriate treatment for the health status of elderly cancer patients and this assessment is recommended for patients over 75 years of age.

Oncogeriatric frailty is based on the SIOG-2 (International Society of Geriatric Oncology-2) clinical scale (assessing comorbidities, autonomy, nutrition, cognitive and thymic domains) defining 3 levels of frailty: (1) harmonious aging, (2) vulnerability (reversible stage), (3) fragility (irreversible stage).

So,the management of very old or very frailty patients with poor tolerance or compliance to treatment, often requires to defer standard treatment and monitoring procedures. That is detrimental to these patients prognosis. By contrast with elderly or very old patients without frailty criteria, could benefit from more efficient procedures.

More generally, frailty is associated directly with a cerebral impact on a cognitive or thymic status or indirectly with the cognitive or thymic impacts related with other components (nutritional or autonomy or walking poor status, comorbidities) 18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET), is routinely performed in follow-up cancer patients in most cases, including older patients, to detect neoplastic localizations on the whole body. It also accurately quantifies cerebral glycolytic metabolism when early brain recording is performed. Brain metabolism reflects the neuronal synaptic activity. It is generally decreased in particular brain areas due of neurodegenerative damage with a little or no symptom, of thymic involvement particular in depression or during accelerated cerebral aging of vascular origin. The impairment of the brain function of the elderly, as evidenced by 18F-FDG PET, is most often multifactorial, as frailty. Above all, brain changes are visualized with 18F-FDG PET much earlier than using neuropsychological tests, especially for cognitive impairment.

Our hypothesis is that with 18F-FDG PET, performed routinely in the initial assessment in elderly patients with cancer, it is also possible to obtain reliable and objective parameters of brain function and frailty. 18F-FDG PET is already used to identify cognitive and thymic impairment. This exam would help to assess the frailty and to adapt as best oncologic treatments some of which can also be neurotoxic. 18F-FDG PET is therefore related to brain function in frail patients

Inclusion Criteria:

• patients who are more than 75 years old with written informed consent
• patients referred for 18F-FDG PET in an oncological disease newly diagnosed
• patients insured under social security

Exclusion Criteria:

• patients with disease in final stage and life expectancy less than 6 months
• patients under guardianship or curators
• patients with abnormal neurological tests: MMS< 27, with neoplastic or other brain lesions or showing ischemic or cerebral stroke damage
• confused or agitated patient unable to realize a PET
• radiotherapy ou chemiotherapy one year at least of the patient enrollment