Access to clinical trials varied by cancer type and racial and ethnic group. The percentage of the US population living within 30 miles of a clinical trial site varied based on cancer diagnosis (breast, 81.8%; colon, 62.9%; lung, 82.0%; pancreatic, 65.7%; and prostate, 81.5%). Racial disparities were also identified, with American Indian and Alaska Native patients consistently having reduced access to clinical trials (eg, 42.1%-60.8% <30 miles from a site) compared with patients from other racial and ethnic groups (eg, 84.7%-95.1% of Asian patients <30 miles from a site) (Table ).Discussion | This quality improvement analysis of clinical trials for metastatic breast, lung, colon, pancreatic, and prostate cancers found that a large proportion of the US population lived within 30 miles of a clinical trial site. This finding suggests that while many clinical trials are available, they are not evenly distributed across the country and may not be accessible to all individuals, particularly racial and ethnic minority individuals. This disparity in access to clinical trials raises important questions about equity and fairness in the distribution of health care resources and opportunities for treatment.Limitations of this study include addressing other barriers to clinical trial access, including a lack of awareness about available trials, concerns about the cost and adverse effects of experimental treatments, and eligibility criteria. Other cancer types and clinical trial phases may have different geographic distributions and accessibility patterns. To address these disparities and ensure equitable access to clinical trials, it will be important to continue to develop innovative solutions that make clinical trials more accessible to all patients, regardless of their location or racial and ethnic group.