A comparison of breast cancer incidence and cancer stages before and after the introduction of the Austrian national breast cancer screening program in the federal state of Salzburg : Real-world data from the Tumor Registry Salzburg.

Background: In January 2014 a national, quality-assured breast cancer screening program was introduced in Austria. To investigate if the program reduced the incidence of advanced breast cancer stages, we evaluated data from the Tumor Registry Salzburg, which records all cancer cases diagnosed in the federal state of Salzburg, Austria. Secondary objectives were changes in nodal status and the influence of age and urban or rural residence on stage distribution.

Methods: Female patients resident in the federal state of Salzburg with a first diagnosis of breast cancer in 2010-2022 were included. For the main objectives, patients aged 45-69 years with known tumor stages were evaluated. Age-standardized incidence rates were compared between 2010-2013 and 2016-2019 by normal approximation of Poisson rates and stage distributions by ordinal logistic regression.

Results: The distribution of stages 0-IV did not differ significantly between 2010-2013 and 2016-2019 (P = 0.380). The percentage of stage IV breast cancer decreased numerically from 9.4-4.5% (P = 0.141). No statistically significant differences between early stages (0-I), advanced stages (II-IV, P = 0. 524) and between lymph node negative and positive cases (P = 0.538) were detected. Neither age nor urban/rural residence had a substantial influence on tumor stage. Interestingly, the breast cancer incidence rates in Salzburg decreased nonsignificantly after the introduction of screening: annual 245.7 vs. 229.8 cases per 100,000 standard population (P = 0.483).

Conclusion: Our findings do not support the assumption that the introduction of the Austrian breast cancer screening program significantly reduced advanced stage breast cancer in the federal state of Salzburg compared to the opportunistic screening established before.