Jacky Luiten

Trends in incidence and tumor grade in screen‐detected DCIS and invasive breast cancer | 25 2 The first FFDM‐only period (2011‐2013) yielded a higher proportion of high grade invasive carcinoma in contrast to the transition cohort (12.0% vs. 7.5%, p =0.014), as was the rate of high grade carcinomas per 1000 women screened (0.6 vs. 0.4 per 1000 screens; p =0.014) However, the overall CDR per 1000 screens was comparable (5.1 vs. 4.6 per 1000 screens; p =0.126). Overall, the SFM‐only periods (2005‐2009) and the FFDM‐only periods (2011‐2015) showed a comparable proportional distribution of B&R grade for invasive carcinoma ( p =0.128). However, the detection rate per 1000 women screened increased for low grade (1.8 vs. 2.4 per 1000 screens) and intermediate grade (1.5 vs. 2.4 per 1000 screens) invasive carcinomas (both p ≤0.001) and remained stable for high grade invasive carcinomas (0.5 vs. 0.7 per 1000 screens; p =0.167). Invasive carcinoma: initial versus subsequent screens Table 2.4 shows the invasive carcinoma proportions, according to B&R grade, at initial and subsequent screening mammography. A total of 2436 invasive carcinomas were diagnosed; 284 (11.7%) at initial screening and 2152 (88.3%) at subsequent screening. The distribution by grade showed no statistically significant difference between initial and subsequent screens ( p =0.063). Table 2.4 DCIS and invasive carcinoma proportions, according to histological grade, at initial and subsequent screening mammography. Initial screens N (%) Subsequent screens N (%) pvalue DCIS 113 (18.1) 510 (81.9) 0.023* Low grade 33 (29.2) 91 (17.8) Intermediate grade 31 (27.4) 168 (32.9) High grade 49 (43.3) 251 (49.2) Invasive carcinoma 284 (11.7) 2152 (88.3) 0.063* Low grade 149 (52.5) 957 (44.5) Intermediate grade 103 (36.2) 910 (42.3) High grade 26 (9.2) 249 (11.6) Unknown 6 (2.1) 36 (1.6) * χ 2 test; in comparison to previous screening cohort; DCIS ductal carcinoma in situ , B&R Bloom & Richardson.