Comprehensive geriatric assessment (CGA) is used to assess older patients’ comorbidities, physical and mental health. CGA can be used to determine eligibility for clinical trials or as an outcome measure.Systematic reviews were conducted to consider the effectiveness and tolerability of systemic anti-cancer therapy for older people with cancer (breast, colorectal, lung, renal cell, chronic myeloid leukaemia and non-Hodgkin lymphoma).Across the six reviews 490 studies were included. CGA use was reported in<10% (n=28) of studies and was used as a baseline assessment measure (n=8), as a patient subgroup category (n=4), as an outcome measure (n=9), and as an inclusion criterion for trial entry (n=7).Review findings demonstrate that CGA is not routinely conducted in clinical cancer studies. The results of the reviews highlight the importance of incorporating standardised CGA tools into the design of future clinical trials that focus on treating older people with cancer. By assessing older people as individuals using CGA tools, the participation of older patients in trials is likely to increase.