Genomic differences between pure ductal carcinoma in situ and synchronous ductal carcinoma in situ with invasive breast cancer.
ABSTRACT: Although ductal carcinoma in situ (DCIS) precedes invasive ductal carcinoma (IDC), the related genomic alterations remain unknown. To identify the genomic landscape of DCIS and better understand the mechanisms behind progression to IDC, we performed whole-exome sequencing and copy number profiling for six cases of pure DCIS and five pairs of synchronous DCIS and IDC. Pure DCIS harbored well-known mutations (e.g., TP53, PIK3CA and AKT1), copy number alterations (CNAs) and chromothripses, but had significantly fewer driver genes and co-occurrence of mutation/CNAs than synchronous DCIS-IDC. We found neither recurrent nor significantly mutated genes with synchronous DCIS-IDC compared to pure DCIS, indicating that there may not be a single determinant for pure DCIS progression to IDC. Of note, synchronous DCIS genomes were closer to IDC than pure DCIS. Among the clinicopathologic parameters, progesterone receptor (PR)-negative status was associated with increased mutations, CNAs, co-occurrence of mutations/CNAs and driver mutations. Our results indicate that although pure DCIS has already acquired some drivers, more changes are needed to progress to IDC. In addition, IDC-associated DCIS is more aggressive than pure DCIS at genomic level and should really be considered IDC. Finally, the data suggest that PR-negativity could be used to predict aggressive breast cancer genotypes.
Project description:Intraductal papillomas (IDP) are challenging breast findings because of their variable risk of progression to malignancy. The molecular events driving IDP development and genomic features of malignant progression are poorly understood. In this study, genome-wide CNA and/or targeted mutation analysis was performed on 44 cases of IDP, of which 20 cases had coexisting ductal carcinoma in situ (DCIS), papillary DCIS or invasive ductal carcinoma (IDC). CNA were rare in pure IDP, but 69% carried an activating PIK3CA mutation. Among the synchronous IDP cases, 55% (11/20) were clonally related to the synchronous DCIS and/or IDC, only one of which had papillary histology. In contrast to pure IDP, PIK3CA mutations were absent from clonal cases. CNAs in any of chromosomes 1, 16 or 11 were significantly enriched in clonal IDP lesions compared to pure and non-clonal IDP. The observation that 55% of IDP are clonal to DCIS/IDC indicates that IDP can be a direct precursor for breast carcinoma, not limited to the papillary type. The absence of PIK3CA mutations and presence of CNAs in IDP could be used clinically to identify patients at high risk of progression to carcinoma.
Project description:<h4>Purpose</h4>Ductal carcinoma <i>in situ</i> (DCIS) is a nonobligate precursor of invasive breast cancer. Here, we sought to investigate the level of intralesion genetic heterogeneity in DCIS and the patterns of clonal architecture changes in the progression from DCIS to invasive disease.<h4>Experimental design</h4>Synchronous DCIS (<i>n</i> = 27) and invasive ductal carcinomas of no special type (IDC-NSTs; <i>n</i> = 26) from 25 patients, and pure DCIS (<i>n</i> = 7) from 7 patients were microdissected separately and subjected to high-depth whole-exome (<i>n</i> = 56) or massively parallel sequencing targeting ?410 key cancer-related genes (<i>n</i> = 4). Somatic genetic alterations, mutational signatures, clonal composition, and phylogenetic analyses were defined using validated computational methods.<h4>Results</h4>DCIS revealed genetic alterations similar to those of synchronously diagnosed IDC-NSTs and of non-related IDC-NSTs from The Cancer Genome Atlas (TCGA), whereas pure DCIS lacked <i>PIK3CA</i> mutations. Clonal decomposition and phylogenetic analyses based on somatic mutations and copy number alterations revealed that the mechanisms of progression of DCIS to invasive carcinoma are diverse, and that clonal selection might have constituted the mechanism of progression from DCIS to invasive disease in 28% (7/25) of patients. DCIS displaying a pattern of clonal selection in the progression to invasive cancer harbored higher levels of intralesion genetic heterogeneity than DCIS where no clonal selection was observed.<h4>Conclusions</h4>Intralesion genetic heterogeneity is a common feature in DCIS synchronously diagnosed with IDC-NST. DCIS is a nonobligate precursor of IDC-NST, whose mechanisms of progression to invasive breast cancer are diverse and vary from case to case.
Project description:A substantial number of ductal carcinoma in situ (DCIS) detected by mammography never progress to invasive ductal carcinoma (IDC) and current approaches fail to identify low-risk patients not at need of adjuvant therapies. We aimed to identify the key miRNAs protecting DCIS from malignant evolution, that may constitute markers for non-invasive lesions. We studied 100 archived DCIS samples, including pure DCIS, DCIS with adjacent IDC and pure DCIS from patients with subsequent IDC in contralateral breast or no recurrence. A DCIS derived cell line was used for molecular and cellular studies. A genome wide study revealed that pure DCIS has higher miR-126 and miR-218 expression than DCIS with adjacent IDC lesions or than IDC. The down-regulation of miR-126 and miR-218 promoted invasiveness in vitro and, in patients with pure DCIS, was associated with later onset of IDC. Survival studies of independent cohorts indicated that both miRNAs play a protective role in IDC. The clinical findings are in agreement with the miRNAs' roles in cell adhesion, differentiation and proliferation. We propose that miR-126 and miR-218 have a protective role in DCIS and represent novel biomarkers for the risk assessment in women with early detection of breast cancer.
Project description:Ductal carcinoma in situ with microinvasion (DCIS-Mi) is an early-stage breast cancer with long-term behavior, prognosis and treatment not fully understood. The aim of our study was to explore the clinicopathological and prognostic features of DCIS-Mi with pure DCIS and IDC-T1 (invasive ductal carcinoma with a tumor size ?2 cm) as control. We retrospectively reviewed 242 cases of DCIS-Mi, 280 cases of pure DCIS, and 347 cases of IDC-T1. The clinicopathological features, therapeutic schemes and survival status were compared among the three groups. After a median follow-up of 109 months, the 5-year disease-free survival (DFS) was lower for the DCIS-Mi patients than for the DCIS patients but higher than the IDC-T1 patients (100%, 96.89% and 87.86% respectively, P<0.001). The 5-year breast cancer specific survival for DCIS-Mi patients was also between that of DCIS and IDC-T1 patients (100%, 99.32%, and 95.42% respectively, P=0.001). Tumor size (P<0.001, HR=18.31, 95% confidence interval (CI) 5.53-60.65) was identified as an independent prognostic factor for recurrence or metastasis. Furthermore, our study indicated that DCIS-Mi patients derived minimal, if any, benefit from chemotherapy treatment after mastectomy (P=0.63, HR=1.50, 95% CI 0.29-7.87). To our knowledge, this is the largest follow-up cohort study on Chinese DCIS-Mi patients. Our data suggested that DCIS-Mi exhibited worse clinical outcome than pure DCIS but better than that of IDC-T1. Tumor size was an independent prognostic factor. Post-mastectomy chemotherapy did not help for increasing DFS for DCIS-Mi patients.
Project description:The mechanisms underlying the progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) of the breast are yet to be fully elucidated. Several hypotheses have been put forward to explain the progression from DCIS to IDC, including the selection of a subpopulation of cancer cells with specific genetic aberrations, and the acquisition of new genetic aberrations or non-genetic mechanisms mediated by the tumour microenvironment. To determine whether synchronously diagnosed ipsilateral DCI and IDCs have modal populations with distinct repertoires of gene copy number aberrations and mutations in common oncogenes, matched frozen samples of DCIS and IDC were retrieved from 13 patients and subjected to microarray-based comparative genomic hybridization (aCGH) and Sequenom MassARRAY (Oncocarta v 1.0 panel). Fluorescence in situ hybridization and Sanger sequencing were employed to validate the aCGH and Sequenom findings, respectively. Although the genomic profiles of matched DCI and IDCs were similar, in three of 13 matched pairs amplification of distinct loci (ie 1q41, 2q24.2, 6q22.31, 7q11.21, 8q21.2 and 9p13.3) was either restricted to, or more prevalent in, the modal population of cancer cells of one of the components. Sequenom MassARRAY identified PIK3CA mutations restricted to the DCIS component in two cases, and in a third case the frequency of the PIK3CA mutant allele reduced from 49% in the DCIS to 25% in the IDC component. Despite the genomic similarities between synchronous DCIS and IDC, our data provide strong circumstantial evidence to suggest that in some cases the progression from DCIS to IDC is driven by the selection of non-modal clones that harbour a specific repertoire of genetic aberrations.
Project description:In the breast, the reduction of invasive ductal carcinoma (IDC) seems to be smaller than expected from an increasing number of ductal carcinoma in situ (DCIS) detection in screening programs, suggesting that some DCIS lesions remain dormant and take a very long time for progression to IDC. However, the progression risk of individual DCIS and papilloma to IDC largely remain unassessable. To tackle this problem, we applied array-based comparative genomic hybridization to DCIS, IDC and papilloma lesions. We confirmed the presence of chromosomal copy-number alterations (CNAs) reported previously in breast cancers and the absence of chromosomal CNAs in the papillomas examined. These findings suggest that gene CNA profile is a good lineage marker for prediction of progression risk of individual tumors and that tumor progression within each lineage is driven by epigenetic rather than genetic alterations. Overall design: Array-based Comparative Genomic Hybridization. Cases include 33 invasive ductal carcinomas, 24 ductal carcinomas in situ and 12 papillomas. IDC samples include 26 ductal components, 30 invasive components and 7 metastatic axillary lymph nodes. There are 26 DCIS samples because two DCIS cases were sampled from two different ductal areas.
Project description:Ductal carcinoma in situ (DCIS) is a precursor lesion of invasive ductal carcinoma (IDC) of the breast. To understand the dynamics of genomic alterations in this progression, we used four multicolor fluorescence in situ hybridization probe panels consisting of the oncogenes COX2, MYC, HER2, CCND1, and ZNF217 and the tumor suppressor genes DBC2, CDH1, and TP53 to visualize copy number changes in 13 cases of synchronous DCIS and IDC based on single-cell analyses. The DCIS had a lower degree of chromosomal instability than the IDC. Despite enormous intercellular heterogeneity in DCIS and IDC, we observed signal patterns consistent with a nonrandom distribution of genomic imbalances. CDH1 was most commonly lost, and gain of MYC emerged during progression from DCIS to IDC. Four of 13 DCISs showed identical clonal imbalances in the IDCs. Six cases revealed a switch, and in four of those, the IDC had acquired a gain of MYC. In one case, the major clone in the IDC was one of several clones in the DCIS, and in another case, the major clone in the DCIS became one of the two major clones in the IDC. Despite considerable chromosomal instability, in most cases the evolution from DCIS to IDC is determined by recurrent patterns of genomic imbalances, consistent with a biological continuum.
Project description:BACKGROUND: The role of mitochondrial DNA (mtDNA) mutations in the development of breast cancer is largely unknown. In this study, we investigated the frequency and pattern of mutations in the D310 region, the most commonly mutated region in mtDNA, in a series of breast lesions. METHODS: Using capillary electrophoresis, we genotyped the D310 sequence of neoplastic epithelial cells from 23 patients with synchronous ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC), 26 patients with IDC only and 29 patients with DCIS only. RESULTS: A majority of DCIS (68.4%) and IDC (71.4%) lesions harbour different D310 sequences compared with their matched normal control. Specific D310 sequences were more frequently identified in tumour samples (77.1% of DCIS and 75.5% of IDC) compared with normal tissues (35.3% of normal; P<0.0001). No difference was identified between DCIS lesions with synchronous IDC and those from pure DCIS cases. In five cases, histologically normal tissue adjacent to tumour was found to share D310 sequences with the tumour, while normal tissue taken further away did not. CONCLUSION: Although D310 alterations do not seem to be related to DCIS progression, they were found in histologically normal cells adjacent to tumour. This suggests a field of genetically altered cells, thus D310 mutations could represent a potential marker for the clonal expansion of premalignant breast cancer cells.
Project description:BACKGROUND: The metastatic propensity of invasive ductal carcinoma (IDC) of the breast correlates with axillary node involvement and with expression of the proliferation antigen Ki-67, whereas ductal carcinoma in situ (DCIS) is non-metastasising. To clarify whether concomitant DCIS affects IDC prognosis, we compared Ki-67 expression and node status of size-matched IDC subgroups either with DCIS (IDC-DCIS) or without DCIS (pure IDC). METHODS: We analysed data from 1355 breast cancer patients. End points were defined by the association of IDC (with or without DCIS) with grade, nodal status, Ki-67, and ER/HER2. RESULTS: Size-matched IDC-DCIS was more likely than pure IDC to be screen detected (P=0.03), to occur in pre-menopausal women (P=0.002), and to be either ER-positive (P=0.002) or HER2-positive (P<0.0005), but less likely to be treated with breast-conserving surgery (P=0.004). Grade and Ki-67 were lower in IDC-DCIS than in pure IDC (P=0.02), and declined as the DCIS enlarged (P<0.01). Node involvement and lymphovascular invasion in IDC-DCIS increased with the size ratio of IDC to DCIS (P<0.01). A 60-month cancer-specific survival favoured IDC-DCIS over size-matched pure IDC (97.4 vs 96.0%). CONCLUSION: IDC co-existing with DCIS is characterised by lower proliferation and metastatic potential than size-matched pure IDC, especially if the ratio of DCIS to IDC size is high. We submit that IDC-DCIS is biologically distinct from pure IDC, and propose an incremental molecular pathogenesis of IDC-DCIS evolution involving an intermediate DCIS precursor that remains dependent for replication on upstream mitogens.
Project description:BACKGROUND:The upgrade rate of biopsy-confirmed ductal carcinoma in situ (DCIS) to invasive carcinoma is up to 50% on final pathology. We investigated MRI and clinicopathologic predictors of the invasive components of DCIS diagnosed by preoperative biopsy and then compared MRI features between patients with DCIS, microinvasive ductal carcinoma (mIDC), and invasive ductal carcinoma (IDC) diagnosed on final pathology. METHODS:Two hundred and one patients with 206 biopsy-confirmed DCIS lesions were enrolled. MRI and clinicopathologic features were used to predict either mIDC or IDC via a cumulative logistic regression analysis. For the lesions detected on MRI, morphologic and kinetic analyses were performed using the Chi-square, Fisher's exact, and Kruskal-Wallis tests. RESULTS:Of all the lesions, 112 (54.4%) were diagnosed as DCIS, 50 (24.3%) were upgraded to mIDC, and 44 (21.4%) to IDC. The detection on MRI as mass (Odds ratio (OR)?=?8.84, 95% confidence interval (CI)?=?1.05-74.04, P?=?0.045) or non-mass enhancement (NME; OR?=?11.17, 95% CI?=?1.35-92.36, P?=?0.025), negative progesterone receptor (PR; OR?=?2.40, 95% CI?=?1.29-4.44, P?=?0.006), and high Ki-67 level (OR?=?2.42, 95% CI?=?1.30-4.50, P?=?0.005) were significant independent predictors of histologic upgrade. On MRI, 87 (42.2%) lesions appeared as mass and 107 (51.9%) as NME. Irregularly shaped, not-circumscribed, heterogeneous, or rim-enhancing masses with intratumoral high signal intensity or peritumoral edema, clumped or clustered ring-enhancing NMEs, and high peak enhancement were significantly associated with histologic upgrade (P?<?0.001). CONCLUSION:MRI detection, negative PR, and high Ki-67 levels are associated with a histologic upgrade in patients with biopsy-confirmed DCIS. Suspicious MRI features are more frequent in such patients.