BACKGROUND:Breast cancer is the leading cancer in terms of incidence and mortality among women in France. Effective organized screening does exist, however, the participation rate is low, and negatively associated with a low socioeconomic status and remoteness.OBJECTIVES:To determine the cost-effectiveness of a mobile mammography (MM) program to increase participation in breast cancer screening and reduce geographic and social inequalities.METHODS:A cost-effectiveness analysis from retrospective data was conducted from the payer perspective, comparing an invitation to a mobile mammography unit (MMU) or to a radiologist's office (MM or RO group) with an invitation to a radiologist's office only (RO group) (n = 37 461). Medical and nonmedical direct costs were estimated. Outcome was screening participation. The mean incremental cost and effect, the incremental cost-effectiveness ratio, and the cost-effectiveness acceptability curve were estimated.RESULTS:The mean incremental cost for invitation to MM or RO was estimated to be €23.21 (95% CI, 22.64-23.78) compared with RO only, and with a point of participation gain of 3.8% (95% CI, 2.8-4.8), resulting in an incremental cost per additional screen of €610.69 (95% CI, 492.11-821.01). The gain of participation was more important in women living in deprived areas and for distances exceeding 15 km from an RO.CONCLUSION:Screening involving a MMU can increase participation in breast cancer screening and reduce geographic and social inequalities while being more cost-effective in remote areas and in deprived areas. Because of the retrospective design, further research is needed to provide more evidence of the effectiveness and cost-effectiveness of using a MMU for organized breast cancer screening and to determine the optimal conditions for implementing it.