Abstract
BACKGROUND: Colorectal cancer (CRC) is the most commonly diagnosed cancer in Bulgaria and the second leading cause of cancer-related death. Bulgaria has increased CRC mortality, highlighting the urgent need for effective screening interventions. This study evaluated the operational outcomes and cost-utility of Bulgaria's first national CRC screening program. METHODS: The screening program targeted individuals aged 50-74 years via the fecal immunochemical test (FIT). Free FIT kits were distributed primarily through laboratories and pharmacies, with placement guided by merchandising best practices to maximize visibility and uptake. A multichannel communication strategy, led by television, encouraged participation. Anonymous demographic, testing, and communication data were analysed to evaluate campaign performance. A centrally coordinated model, organized by the Lachezar Tsotsorkov Foundation, ensured consistency, efficiency, and national reach. Cost-utility analysis (CUA) based on a Markov model with a lifetime horizon was conducted from the payer's perspective, comparing screening versus no screening. Transition probabilities were sourced from published analyses in the Netherlands, the SEER database, and a Danish study. Probabilistic sensitivity analysis was used to assess the impact of parameter uncertainty. RESULTS: A total of 93,381 individuals were screened, exceeding the original target by 86%. Of these, 14.2% tested positive. While women represented 63.3% of the participants, men had a higher positivity rate (18.2% vs. 11.9%). In the target population (individuals aged 50-74 years), 9,380 (14.4%) tests were positive. The most influential communication channel was television (45.1%), followed by personal networks (24.6%). The cost per participant was calculated at €7.84 (BGN 15.34), which includes the cost of the tests, management expenses and promotion of the screening program. The results of the CUA estimates €67.07 (BGN 131.18) savings and +1.58 QALY gained per patient detected, projecting an incremental national gross domestic product contribution of up to €15.9 million (assuming full return to work capacity per quality-adjusted life year and actual productivity gains). CONCLUSION: A centrally coordinated, data-responsive, and well-communicated screening program can achieve high participation and early detection. The presented model offers a scalable cost-effective (feasible and economically justified) framework for national CRC prevention efforts in Bulgaria and other settings facing rising CRC burdens. TRIAL REGISTRATION: Not applicable.