School-Based Cancer Education and Health Literacy: A Pre–Post Study on Cancer Prevention and System Navigation Among Brazilian Adolescents

BACKGROUND: Cancer incidence in Brazil is projected to reach approximately 781,000 new cases annually in 2026-2028, with persistent regional and social inequalities. School-based interventions may represent an upstream strategy to improve cancer literacy and promote equity-oriented prevention. OBJECTIVE: To evaluate the immediate impact of a structured cancer education intervention on knowledge, beliefs, emotional responses, and health system navigation among Brazilian public school adolescents. Methods A repeated cross-sectional pre-post study was conducted among 8th-grade students from public schools (pre-test n = 910; post-test n = 888). The educational intervention addressed cancer epidemiology, modifiable risk factors, warning signs, stigma, and navigation within the Brazilian Unified Health System (SUS). Differences between assessments were analyzed using Pearson's chi-square test. Effect sizes were estimated using Cramér's V. RESULTS: Significant improvements were observed in knowledge of cancer incidence (39.9% vs. 67.8%, p < 0.001, V = 0.59) and modifiable risk factors, particularly overweight (43.9% vs. 82.9%, V = 0.39), physical inactivity (48.9% vs. 86.6%, V = 0.39), and alcohol consumption (65.1% vs. 91.7%, V = 0.32). Recognition of cancer warning signs increased from 40.5% to 73.6% (p < 0.001, V = 0.33). Correct identification of the Basic Health Unit as the appropriate SUS entry point rose from 10.8% to 37.2% (p < 0.001, V = 0.33). When reflecting on cancer, participants reported a modest increase in negative emotional responses, including anxiety, sadness, and feelings of insecurity, whereas levels of fear remained relatively stable over time. Notably, motivation to engage in discussions about cancer with family members and to adopt healthier lifestyle behaviors increased significantly, suggesting a shift toward greater proactive engagement despite heightened emotional awareness. CONCLUSIONS: This school-based intervention produced meaningful short-term improvements in cancer literacy and system-oriented health knowledge. Integrating structured cancer education into public school curricula may contribute to long-term reductions in socially patterned disparities in cancer prevention and access to care.