Abstract P5-17-02: Treatment and prognosis of DCIS during twenty years. A population-based register study from a Swedish cohort

Abstract

Abstract The increasing incidence of ductal carcinoma in situ (DCIS) of the breast has been attributed to the wide adoption of mammography screening programmes. The aim of the present study was to analyse trends in incidence, treatment and outcome of DCIS over a 20-year time period in a Swedish health care region, with a source population of two million, based on systemically collected data in a regional Breast Cancer Quality Registry started in 1992. All patients registered with a diagnosis of primary DCIS in the Breast Cancer Quality Registry in the Uppsala-Örebro healthcare region between 1992 and 2012 were included. The study period was divided into four time periods. The registry contains information on tumour characteristics, treatment and follow-up data and is linked to the Swedish cancer registry, to which reporting of all newly diagnosed malignant tumours in Sweden is mandated. To verify the validity of the Breast Cancer Quality Registry, 300 women recorded with a diagnosis of DCIS were randomly selected and their medical records were collected to compare clinical data, treatment data and subsequent breast cancer events compared to registry data. The completeness and reliability of the registration of most key variables were overall good, 91-99%. A total of 2,952 patients with DCIS were registered, of which eight were men. The proportion of DCIS to all diagnosed breast cancers was 9.5%, with no clear increase over time. The majority of the DCIS cases were detected by screening (68%). Tumour size increased over time; in 1992-1997 36.4% were larger than 15mm compared to 64.8% in 2008-2012. The frequency of mastectomy increased from 23.0% to 39.0% and the proportion of patients receiving adjuvant radiotherapy after breast-conserving surgery increased from 30.1% to 67.6%. Axillary lymph node clearance declined over time while the proportion of patients who underwent sentinel node biopsy increased from 1.4% in 1998-2002 to 33.9% in 2003-2007 and 54.9% in 2008-2012. 1992-19971998-20022003-20072008-2012P valueCases693628835796 DCIS size > 15mm252(36.4%)257(40.9%)339(53.8%)511(64.2%)<0.0001Mastectomy161(23.2%)150(23.9%)323(38.7%)313(39.3%)<0.0001BCS519(74.9%)468(74.5%)506(60.6%)476(59.8%)<0.0001BCS+RT156/519(30.0%)178/468(38.0%)347/506(68.6%)322/476(67.6%)<0.0001BCS= Breast conserving surgery, RT= radiotherapy There was no statistical difference in the cumulative incidence of recurrent breast events over time or between different treatment modalities. The relative 5- and 10- year survival rates were 99.0% and 97.0% respectively with no clear trend over time. In conclusion, while the proportion of DCIS did not increase over time between 1992 and 2012, there was a trend towards more intensified management to achieve local control. The increased tumor size over time could be secondary to a higher diagnostic activity, which clearly is manifested by the increased use of sentinel node biopsy. Citation Format: Wadsten C, Heyman H, Holmqvist M, Ahlgren J, Lambe M, Sund M, Wärnberg F. Treatment and prognosis of DCIS during twenty years. A population-based register study from a Swedish cohort. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-17-02.