AIM The aim of this systematic review is to summarise all available data on the effect of a geriatric evaluation on the multidisciplinary treatment of older cancer patients, focussing on oncologic treatment decisions and the implementation of non-oncologic interventions. METHODS A systematic search in MEDLINE and EMBASE for studies on the effect of a geriatric evaluation on oncologic and non-oncologic treatment for older cancer patients. RESULTS Literature search identified 1654 reports (624 from Medline and 1030 from Embase), of which 10 studies were included in the review. Three studies used a geriatric consultation while seven used a geriatric assessment performed by a cancer specialist, healthcare worker or (research) nurse. Six studies addressed a change in oncologic treatment, the initial treatment plan was modified in a median of 39% of patients after geriatric evaluation, of which two thirds resulted in less intensive treatment. Seven studies focused on the implementation of non-oncologic interventions based on the results of the geriatric evaluation; all but one reported that interventions were suggested for over 70% of patients, even in studies that did not focus specifically on frail older patients. In the other study, implementation of non-oncologic interventions was left to the cancer specialist's discretion. CONCLUSION A geriatric evaluation has significant impact on oncologic and non-oncologic treatment decisions in older cancer patients and deserves consideration in the oncologic work-up for these patients.