Abstract IA030: Molecular subtypes and spatial heterogeneity in DCIS

Abstract

Abstract The large heterogeneity of DCIS complicates the identification of markers for risk of progression to invasive breast cancer. Molecular and cellular heterogeneity is observed across DCIS, between multiple foci of DCIS within a lesion and within mixed lesions of invasive tumors with DCIS foci. The intrinsic breast cancer subtypes represent fundamental biological properties of the disease and are also found at the DCIS stage. However, their frequency and relevance as prognostic markers in pre-invasive stage is still not clear. Novel technologies for spatial characterization of tumors allow detailed mapping of DCIS and the microenvironment and may give us clues to which DCIS have the propensity to invade surrounding stroma. In the presentation, we will discuss results from our ongoing genomic characterization of DCIS and invasive breast carcinomas that illustrate the need for stratification when searching for prognostic markers. We have found disproportionate distribution and characteristics of the intrinsic subtypes in DCIS compared with invasive breast cancer and the dominance of Luminal A and HER2 subtypes. Bona-fide basal-like tumors may rarely be found at the DCIS stage and HER2-enriched DCIS are associated with specific immune cell profiles. Citation Format: Therese Sørlie. Molecular subtypes and spatial heterogeneity in DCIS [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr IA030.