Jacky Luiten

48 | Chapter 4 Abstract Between January 1, 2011, and December 31, 2016, we studied the incidence, management and outcome of high‐risk breast lesions in a consecutive series of 376,519 screens of women who received biennial screening mammography. During the 6‐year period covered by the study, the proportion of women who underwent core needle biopsy (CNB) after recall remained fairly stable, ranging from 39.2% to 48.1% (mean: 44.2%, 5,212/11,783), whereas the proportion of high‐risk lesions at CNB (i.e., flat epithelial atypia, atypical ductal hyperplasia, lobular carcinoma in situ and papillary lesions) gradually increased from 3.2% (25/775) in 2011 to 9.5% (86/901) in 2016 ( p <0.001). The mean proportion of high‐risk lesions at CNB that were subsequently treated with diagnostic surgical excision was 51.4% (169/329) and varied between 41.0% and 64.3% through the years, but the excision rate for high‐risk lesions per 1,000 screens and per 100 recalls increased from 0.25 (2011) to 0.70 (2016; p <0.001) and from 0.81 (2011) to 2.50 (2016; p <0.001), respectively. The proportion of all diagnostic surgical excisions showing in situ or invasive breast cancer was 29.0% (49/169) and varied from 22.2% (8/36) in 2014 to 38.5% (5/13) in 2011. In conclusion, the proportion of high‐risk lesions at CNB tripled in a 6‐year period, with a concomitant increased excision rate for these lesions. As the proportion of surgical excisions showing in situ or invasive breast cancer did not increase, a rising number of screened women underwent invasive surgical excision with benign outcome. What ’ s new? Screening mammography aims to catch breast cancer early to reduce associated morbidity and mortality. Women with suspect findings at mammography frequently are recalled for further testing with core needle biopsy (CNB). In this investigation, the proportion of high‐risk lesions detected at CNB was found to have tripled among women in the Netherlands who underwent mammographic screening between 2011 and 2016. This increase was accompanied by an increase in lesion excision rates. Of excised lesions, little more than 14% proved to be malignant at two‐year follow‐up. The remainder of lesions exhibited benign pathology, suggesting that many women underwent potentially unnecessary surgery.