Understanding Barriers to Clinical Trial Participation Among Cancer Patients: Insights from a Brazilian Oncology Center

Abstract Clinical trials are essential for advancing cancer care, yet patient participation remains low, particularly in regions with limited awareness such as Brazil. This cross-sectional survey was conducted between 2020 and 2022 at a single cancer center in São Paulo, Brazil. Adult cancer patients completed a structured questionnaire assessing awareness and barriers to clinical trial participation, categorized as patient-, protocol-, or physician-related. Among the 206 oncologic patients enrolled in the study, 83.5% were female and 43.7% were treated in the public health system. The percentages of patients who self-identified as White and Brown/Black were 59.7 and 35.9%, respectively. Patient-related barriers included unfamiliarity with trial participants (84.6%), concerns about daily life disruptions (75.4%), and transportation difficulties (66.2%). Protocol-related barriers included fear of unknown side effects (62.3%), inability to choose treatment (47.6%), and potential assignment to the placebo group (46.8%). Physician-related barriers included communication issues, weak doctor-patient relationships (94.7%), and patient deference to doctors' decisions (55.4%). Patients with higher income (OR: 3.60; 95% CI: 1.18–10.9) and those treated in the public system (OR: 3.69; 95% CI: 1.58–8.63) were more likely to be aware of clinical research. This study highlights the multifactorial nature of barriers to clinical trial participation in Brazil, where access disparities persist. Increasing patients' educational level, enhancing doctor–patient communication, and addressing structural disparities are essential steps towards improving trial enrollment and promoting fair access to innovation in cancer care.