Clinical guidelines for the management of mammographic density: a systematic review of breast screening guidelines worldwide

Background: High breast density is an independent risk factor for breast cancer and decreases the sensitivity of mammography. This systematic review synthesizes the international clinical guidelines and the evidence base for screening and supplemental screening recommendations in women with dense breasts. Methods: A systematic search of CINHAL, Embase, and Medline databases was performed in August 2023 and grey literature searched in January 2024. Two authors independently assessed study eligibility and quality (Appraisal of Guidelines for Research and Evaluation II instrument). Results: Of 3809 articles, 23 guidelines published from 2014 to 2024 were included. The content and quality varied between the guidelines; the average AGREE II total score was 58% (range = 23%-87%). Most guidelines recommended annual or biennial screening mammography for women more than 40 years old with dense breasts (n = 16). Other guidelines recommended breast tomosynthesis (DBT, n = 6) or magnetic resonance imaging (MRI, n = 1) as the preferred screening modality. One third of the guidelines (n = 8) did not recommend supplemental screening for women with dense breasts. Of those that recommended supplemental screening (n = 14), ultrasound was the preferred modality (n = 7), with MRI (n = 3), DBT (n = 3), and contrast-enhanced mammography (n = 2) also recommended. Conclusions: Consensus on supplemental screening in women with dense breasts is lacking. The quality of the guidelines is variable, and recommendations are based largely on low-quality evidence. As evidence of the benefits versus harms of supplemental screening in women with dense breasts is evolving, it is imperative to improve the methodological quality of breast cancer screening and supplemental screening guidelines.