Breast Density Impact on Mammographic Screening for Breast Cancer Diagnosis

This retrospective, monocentric, observational study investigates the impact of breast density on mammographic screening performance in the regional program "Prevenzione Serena," implemented at ASL CN2 (Piedmont, Italy). The primary objective is to evaluate the association between BI-RADS breast-density categories and the frequency of recalls for second-level diagnostic examinations among women aged 45-75 undergoing screening mammography between 25 September 2023 and 3 May 2024.

Breast density is a known factor that can reduce the sensitivity of mammography. Dense fibroglandular tissue appears radiopaque and may mask suspicious lesions, leading to false-negative or false-positive examinations. Women with dense breasts (BI-RADS categories C-D) also have an independently increased risk of breast cancer. For these reasons, the study aims to characterize how breast density influences recall rates, diagnostic appropriateness, and overall screening performance in a real-world population.

A secondary goal is the internal validation of Insight BD, an automated breast-density assessment software integrated into the Siemens Mammomat Revelation mammography system used at ASL CN2. The validation includes:

• Technical validation using a dedicated mammographic phantom with known density values to determine measurement accuracy and repeatability;
• Diagnostic validation through comparison between the BI-RADS density category assigned by the software and those assigned by two radiologists (one expert, one non-expert).

The study will also examine associations between breast density and key clinical factors, including menopausal status, family history of breast cancer, and systemic hormone therapy. Furthermore, the frequency of false-positive recalls (additional testing without a final diagnosis of cancer) will be assessed, given their clinical, psychological, and organizational implications.

The study aims to characterize density-related patterns in screening performance, quantify false-positive recalls, and contribute evidence to support future updates to breast-screening guidelines and potential personalized screening strategies, especially for women with dense breast tissue.

Inclusion criteria

• Women aged 45 to 75 years who participated in the "Prevenzione Serena" mammography screening program and underwent screening mammography at ASL CN2 between September 25, 2023, and May 3, 2024.
• Signed informed consent or equivalent substitute declaration, when applicable.

Exclusion criteria

• Women with a history of mastectomy.
• Women with breast implants.
• Women with cardiac implantable devices, such as pacemakers or loop recorders.
• Cases in which the Insight BD software cannot be applied due to compression thickness below 15 mm.