Abstract 4348: In depth molecular analysis of 183 primary DCIS lesions and 78 subsequent invasive breast cancers
Authors: Visser Lindy , Hoogstraat Marlous , Kucukosmanogl Asli , Nieboer Frank , Maaker Michiel de , Kristel Petra , Mulder Lennart , Elshof Lotte , Leeuwen Flora van , Rutgers Emiel , Schmidt Marjanka K. , Lips Esther , Wesseling Jelle 
Published: August 2018

Abstract
Background. Ductal carcinoma in situ (DCIS) is a potential precursor of invasive breast cancer (IBC). As we are currently unable to predict which DCIS lesions will progress to IBC, almost all women with DCIS are treated with surgical treatment, adjuvant therapy, or both. Yet, most DCIS lesions will never progress, implying overtreatment in many women. To increase our knowledge of DCIS and improve DCIS risk stratification, we performed a molecular characterization of a large series of DCIS lesions with long-term follow-up.
Patients and methods. We made use of a DCIS case-control series, nested in a nation-wide population-based cohort of Dutch women diagnosed with primary DCIS and treated with breast conserving surgery alone between 1989-2005. Mean follow-up time was 12.0 years. DNA and RNA were simultaneously extracted from FFPE laser-microdissected tissue fragments of 183 primary DCIS lesions (100 associated with subsequent invasive recurrences; and 83 which remained free of invasive recurrence during the same follow-up duration) and 78 matched subsequent ipsilateral IBCs. RNA sequencing (RNAseq) and low coverage DNA sequencing (CNVseq) were performed to identify differentially expressed and aberrated genes between DCIS with and without an invasive recurrence and to compare primary DCIS and its subsequent IBC.
Results. After exclusion of samples with poor data quality, 158 DCIS lesions and 72 IBCs (88%) were included for CNVseq analysis and 155 DCIS lesions and 68 IBCs (85%) were included in the RNAseq analysis. CNVseq analysis identified copy number aberrations of known breast cancer-related genes. Amplification of FGFR1, CCND1, ZNF217, and ERBB2 was found in 16, 19, 22, and 44 DCIS samples, respectively. Furthermore, loss of CBFB, CDKN2A, CDKN2B, TP53, and MAP2K4 was found in 10, 11, 11, 11, and 14 DCIS samples, respectively. Deletion of CBFB, TP53, and CDH1 was more often detected in DCIS with subsequent IBC as compared of DCIS without invasive recurrence. When comparing DCIS and subsequent IBC, aberrations of breast cancer-related genes were mostly comparable. RNAseq analysis revealed genes, differentially expressed between DCIS with and without subsequent IBC, which were enriched in immune-related pathways.
Conclusion. We performed the first large-scale analysis of primary DCIS lesions with and without subsequent invasive recurrences, with long-term follow-up. Our data show differences in aberrated genes between DCIS with and without subsequent IBC, whereas DCIS and subsequent IBC were more alike. Furthermore, our transcriptomic data suggest that immune-related pathways are involved in DCIS progression. More extensive data analysis will be presented at AACR 2018. The results of our unique study add to the current understanding of DCIS and allow optimized risk stratification of DCIS in the near future.
Citation Format: Lindy Visser, Marlous Hoogstraat, Asli Kucukosmanogl, Frank Nieboer, Michiel de Maaker, Petra Kristel, Lennart Mulder, Lotte Elshof, Flora van Leeuwen, Emiel Rutgers, Marjanka K. Schmidt, Esther Lips, Jelle Wesseling. In depth molecular analysis of 183 primary DCIS lesions and 78 subsequent invasive breast cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4348.