Jacky Luiten

40 | Chapter 3 The rate of primary excision biopsies per 1000 screens decreased over the years from 3.4 in 1997‐1998 to 0 per 1000 screens in 2015‐2016 ( p <0.001, Figure 3.3). The rate of secondary excision biopsies per 1000 screens decreased initially from 1.0 performed in 1997‐1998 to 0.3 per 1000 screens in 2005‐2006 ( p <0.001). After that period a significant increase to 0.6 per 1000 screens was observed in 2015‐2016 ( p =0.003, Figure 3.3). Histological diagnosis of excision biopsies The final histopathological diagnosis was benign in 442 (48.7%) of the 908 women who underwent an excision biopsy. The percentage of benign excision biopsy results increased from 32.2% (69/214 patients), in 1997‐1998, to 70.2% (59/84 patients) in 2015‐2016 ( p <0.001). Figure 3.2 shows the benign versus (pre‐) malignant ratio in excision biopsies per 1000 screens. The benign versus (pre‐) malignant biopsy ratio increased from 0.5 (1997‐1998) to 2.4 in (2015‐2016; p <0.001, Table 3.1). Figure 3.2 Benign versus (pre‐)malignant excisional biopsies per 1000 screens. Of all 411 primary excision biopsies, 134 (32.6%) were benign. Of all 497 secondary biopsies, 303 (61.0%) showed a benign histopathological diagnosis. This percentage increased from 40.4% (19 out of 47) in 1997‐1998 to 70.2% (59 out of 84) in 2015‐2016 (Table 3.1). The (pre‐)malignant histopathological results of secondary excision biopsies in the three most recent cohorts (2011‐2012, 2013‐2014 and 2015‐2016) were further analyzed. Of all 211 biopsies, only 56 showed a (pre‐)malignant histopathological result, resulting in an overall upgrade rate of 26.5%. Of all secondary biopsies 18.5% showed DCIS (27 low grade,