PURPOSE: Lobular carcinoma in situ (LCIS) is a preinvasive lesion of the breast. We sought to define its genomic landscape, whether intralesion genetic heterogeneity is present in LCIS, and the clonal relatedness between LCIS and invasive breast cancers. Experimental Design: We reanalyzed whole-exome sequencing (WES) data and performed a targeted amplicon sequencing validation of mutations identified in 43 LCIS and 27 synchronous more clinically advanced lesions from 24 patients [9 ductal carcinomas in situ (DCIS), 13 invasive lobular carcinomas (ILC), and 5 invasive ductal carcinomas (IDC)]. Somatic genetic alterations, mutational signatures, clonal composition, and phylogenetic trees were defined using validated computational methods.
RESULTS: WES of 43 LCIS lesions revealed a genomic profile similar to that previously reported for ILCs, with CDH1 mutations present in 81% of the lesions. Forty-two percent (18/43) of LCIS were found to be clonally related to synchronous DCIS and/or ILCs, with clonal evolutionary patterns indicative of clonal selection and/or parallel/branched progression. Intralesion genetic heterogeneity was higher among LCIS clonally related to DCIS/ILC than in those nonclonally related to DCIS/ILC. A shift from aging to APOBEC-related mutational processes was observed in the progression from LCIS to DCIS and/or ILC in a subset of cases.
CONCLUSIONS: Our findings support the contention that LCIS has a repertoire of somatic genetic alterations similar to that of ILCs, and likely constitutes a nonobligate precursor of breast cancer. Intralesion genetic heterogeneity is observed in LCIS and should be considered in studies aiming to develop biomarkers of progression from LCIS to more advanced lesions.
Bibliographical noteFunding Information:
J.S. Reis-Filho is funded in part by the Breast Cancer Research Foundation. S. Piscuoglio is funded by the Swiss National Science Foundation (Ambizione grant number PZ00P3_168165). R.S. Harris is the Margaret Harvey Schering Land Grant Chair for Cancer Research, a Distinguished McKnight University Professor, and an Investigator of the Howard Hughes Medical Institute. Research reported in this publication was supported in part by 2009 Komen Career Catalyst Award (T.A. King), 2012 Komen Investigator Initiated Research Award (T.A. King), Susan G. Komen for the Cure, and by a Cancer Center Support Grant of the NIH/NCI (grant no. P30CA008748).
© 2018 American Association for Cancer Research.
PubMed: MeSH publication types
- Research Support, Non-U.S. Gov't
- Journal Article
- Research Support, N.I.H., Extramural