This is a multicenter, open-label, cluster randomized controlled trial in Jiangsu Province, China. Approximately 80,000 women aged 65 to 80 years will be enrolled. Participating community health service stations will be assigned to either active breast ultrasound screening or routine health management. Women in the screening group will receive a standardized breast ultrasound examination, while those in the control group will receive no additional study-specific breast screening. The primary outcome is the difference between groups in the proportion of diagnosed breast cancers that are stage I or II during 24 months of follow-up. The study will also assess other screening-related and implementation outcomes.
