Heindl F, Fasching PA, Hein A, et al. - This study was undertaken to explore if percentage mammographic density (PMD) is associated with a difference in disease-free or overall survival in primary breast cancer (BC) patients. Researchers recruited a total of 2,525 patients with primary, metastasis-free BC for this analysis. PMD was assessed by two readers using a semi-automated method for all patients. They assessed the relationship between PMD and prognosis using Cox regression models with disease-free survival and overall survival as the outcome, and the following adjustments: age at diagnosis, year of diagnosis, body mass index, tumor stage, grading, lymph node status, hormone receptor and HER2 status. The collective PMD is not associated with disease-free and overall survival in patients with BC, although MD is one of the strongest independent risk factors for BC.