Introduction: Lung cancer remains the leading cause of cancer-related mortality worldwide, frequently due to late-stage diagnosis. While low-dose computed tomography (LDCT) is a well-established screening modality for reducing mortality, its large-scale implementation faces substantial logistical hurdles, especially in regions characterized by geographic dispersion and limited access to specialized care. To address these barriers, Barretos Cancer Hospital developed a pioneering screening program centered on active outreach as its primary recruitment and management strategy. Objectives: To describe the active outreach recruitment and tailored adherence and retention strategies, alongside participants' sociodemographic, smoking, and ancestry profiles, while evaluating patient engagement within a mobile lung cancer screening program. Methods: This observational study included individuals aged 55 to 74 years, current and former smokers, recruited through active outreach in multiple municipalities in the Barretos region, São Paulo State, Brazil. Recruitment was conducted using pre-screened and active outreach strategies, varying according to local contexts (urban areas, rural settings, and high-traffic locations frequented by populations at risk). Sociodemographic characteristics, smoking history, genetic ancestry compared with self-reported race, geographic distribution of the sample, and screening outcomes were analyzed. Adherence was assessed by attendance at the initial LDCT examination, and retention by return for follow-up screening examinations. Results: Of the 2,985 individuals initially assessed through active outreach, 1,592 were enrolled in the program, and 1,514 (95%) completed the baseline LDCT examinations. The majority of participants were classified as Lung-RADS® 1 or 2 (87.3%), whereas 8.0% presented findings categorized as Lung-RADS® 3 or higher (4a, 4b, or 4x). Ancestry analysis revealed significant genetic heterogeneity within self-reported racial groups, underscoring the limitations of self-reported race as a proxy for genetic background. The study achieved broad geographic reach, with high-risk population coverage varying significantly across municipalities (ranging from 0.4% to 70%). Among participants eligible for follow-up by March 2024 (n = 996), the overall return rate was 62%, with 43% returning within a 15-month window. Conclusions: The Barretos Cancer Hospital lung cancer screening program successfully engaged diverse populations and achieved substantial baseline adherence. While active outreach proved to be a pivotal strategy for initial recruitment, long-term participant retention remains a significant challenge, highlighting the need for enhanced engagement protocols.