Abstract PD5-02: Dcis as a risk lesion for invasive breast cancer and death from other cancers

Abstract

Abstract Introduction: Ductal carcinoma in situ (DCIS) is considered a non-obligatory precursor of invasive breast cancer. Using a prospective cohort study of screen detected non-invasive neoplasia from a national breast screening program, this analysis examined subsequent DCIS or invasive cancers and death due to other cancers or other causes. Methods: Prospective data on 9191 screen detected non-invasive breast neoplasia with a median 9.2 years follow up was matched to a subsequent diagnosis of invasive breast cancer or death from another primary, non-breast cancer at any site or other cause of death, cross validating data from the National Cancer Registry, Hospital Episode Statistics and mortality data. Results: Following a diagnosis of screen detected DCIS, in 9191 women, for those undergoing breast conservation surgery (BCS), 413 women developed ipsilateral invasive breast cancer, at a proportion of 5/1000 per annum consistent over a decade and more. By contrast DCIS re-occurances in the same, conserved, breast (in 222 women) occurred at a similar rate for the first 5 years then the rate halved beyond 5 years. Contralateral breast cancer (DCIS or invasive) occurred in 431 women over the same time period. Mortality occurred in 1062/9191 (11.6%) women, attributed to breast cancer in 130/1062 (12.2%) and due to cancer at other sites in 397/1062 (37.4%). Death from other, non-breast, cancers was predominantly from primaries of the lung (98 women), ovary (43), pancreas (37) and colon (23) and rarely associated with a confounding diagnosis of invasive breast cancer (present in only 8% of those patients). Non-cancer mortality was identified in 496/1062 (46.7%) women, most commonly attributed to cardiovascular disease (in 188 women) or disease of the respiratory system (in 93). Conclusion: Screen detected DCIS is a marker for subsequent invasive breast cancer, but mortality from other, non-breast, cancers following treatment for DCIS is three times more likely than death due to breast cancer, suggesting DCIS is a more general marker for subsequent cancers than hitherto recognized. Awareness of, and potentially screening for, other cancers should be considered in women treated for DCIS. Citation Format: Alastair Thompson, Bridget Hilton, Joanna Dulson-Cox, Karen Clements, Sloane Project NHS Breast Screening Group. Dcis as a risk lesion for invasive breast cancer and death from other cancers [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD5-02.