Analysis of the influence of the singular risk factors age and breast density on the 2-year incidence of breast cancer among participants in the German mammography screening program.
 The multicenter study includes 111 456 subsequent round digital mammographic screening examinations from four screening units with prospective visual categorization of breast density. Based on detection in screening and during the 2-year interval after negative screening participation (interval cancers), 2-year breast cancer incidences (2 YBCI) (‰) were calculated in the 5-year age groups (5 YAG) of the target group 50-69 years and in the BI-RADS density categories ACR 1-4. Multivariate statistical evaluations were carried out using logistic regression models.
 With an increase in the 5 YAG, the 2 YBCI increased by 5.0 ‰, 6.7 ‰, 8.5 ‰ to 9.7 ‰, and was significantly different among 55-59, 60-64 and 65-69-year-old women compared to the youngest reference group 50-54 years (odds ratio (OR): 1.34; 1.68; and 1.93; p-value < 0.0001). With an increase in density categories 1-4, the 2 YBCI increased from 2.6 ‰, to 5.8 ‰, 9.6 ‰, and 9.7 ‰. The 2 YBCI differed significantly in breast density categories 2, 3, 4 from reference group 1 (OR: 2.17; 3.65; and 3.76; p-value < 0.0001). Only within the two main breast density groups 2 (frequency 44.3 %) and 3 (44.7 %), a significant increase in the 2 YBCI was observed across the 5 YAG (category 2: 3.7-8.9 ‰; category 3: 5.8-11.7 ‰; p-value < 0.001 each). The 2 YBCI was above the median of 7.5 ‰ in women with breast density category 2 and aged 65-69 years, as well as in women with breast density categories 3 and 4 aged 55-69 years. A 2 YBCI below the median was seen in women between 50-54 years regardless of breast density, as well as women in category 1 in all age groups.
 Within the main breast density categories 2 and 3 (almost 90 % of participants), incidences increase with age to double. A consistently low incidence is found regardless of breast density at a young screening age and in women with the lowest breast density.
  · The risk of breast cancer is modified by age in density categories.. · Women aged 50-54 years have a low risk in all density categories.. · Women in category ACR 1 of any age group have a low risk..
· Weigel S, Heindel W, Dietz C et al. Stratifizierung des Brustkrebsrisikos hinsichtlich der Einflüsse von Alter und mammografischer Dichte. Fortschr Röntgenstr 2020; DOI: 10.1055/a-1100-0016.

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