Project Description (abstract) Despite intensive efforts to increase participation, fewer than two percent of US adults are enrolled in clinical trials. More than 40% of National Cancer Institute (NCI)-sponsored trials fail to complete accrual. Clinical trial eligibility criteria present one of the most significant barriers to study accrual and one of the few accrual factors directly controlled by investigators and sponsors. Prior cancer is a widespread exclusion criterion in cancer trials. Our study will provide novel evidence required to objectively reconsider the exclusion of cancer survivors with newly diagnosed (incident) cancer from cancer clinical trials. Specifically, in two aims, we will 1) systematically review how this criterion is incorporated in NCI-sponsored trial protocols and 2) evaluate the impact of prior cancer on cause-specific and all-cause mortality for older patients with six common and deadly cancers: breast, colorectal, kidney, liver, Non-Hodgkin’s lymphoma, and pancreas. We will conduct these analyses using sophisticated epidemiologic and statistical methods applied to high-quality, population-based SEER-Medicare data. We will quickly disseminate findings via our External Advisory Board comprised of national leaders in clinical trials and patient advocates. The potential impact of this work to change research and practice is enormous. More than one third of all people diagnosed with cancer in the US are diagnosed with one of the six cancer types in this proposal; and of these, an estimated 13.5% of those over age 65 years have a prior cancer history and thus are at risk of systematic exclusion from cancer trials.