Older cancer patients in cancer clinical trials are underrepresented. Systematic literature review of almost 5000 meta- and pooled analyses of phase III randomized trials of survival from breast, prostate and lung cancer. BACKGROUND: Older people represent increasing proportions of the population with cancer. To understand the representivity of cancer treatments in older people, we performed a systematic literature review using PRISMA guidelines of the age distribution of clinical trial participants for three leading cancer types, namely breast, prostate, and lung. METHODS: We used PubMed to identify articles detailing meta or pooled-analyses of phase III, randomised controlled trials (RCTs) of survival for breast, prostate and lung cancer, published ≤5 years from 2016. We compared the age distribution of participants to that of these cancers for "More developed regions". RESULTS: 4993 potential papers were identified, but only three papers on breast cancer, three on lung cancer, and none on prostate cancer presented the age distribution of their participants. Except for one paper of breast cancer, participants ≥70 years in all other papers were underrepresented. CONCLUSIONS: We recommend the age distribution of patients be clearly reported in all clinical trials, as per guidelines. Clinical trials ought to be more representative of the populations most affected by the disease for which treatments are being tested. This should lead to better knowledge of effectiveness of treatments and better translation of trial results to optimal care of older cancer patients.