Genetic predisposition to ductal carcinoma in situ of the breast

Ductal carcinoma in situ of the breast: finding the balance between overtreatment and undertreatment

Ductal carcinoma in situ (DCIS) accounts for 15-25% of all breast cancer diagnoses. Its prognosis is excellent overall, the main risk being the occurrence of local breast events, as most cases of DCIS do not progress to invasive cancer. Systematic screening has greatly increased the incidence of this non-obligate precursor of invasion, lending urgency to the need to identify DCIS that is prone to invasive progression and distinguish it from non-invasion-prone DCIS, as the latter can be overdiagnosed and therefore overtreated. Treatment strategies, including surgery, radiotherapy, and optional endocrine therapy, decrease the risk of local events, but have no effect on survival outcomes. Active surveillance is being evaluated as a possible new option for low-risk DCIS. Considerable efforts to decipher the biology of DCIS have led to a better understanding of the factors that determine its variable natural history. Given this variability, shared decision making regarding optimal, personalised treatment strategies is the most appropriate course of action. Well designed, risk-based de-escalation studies remain a major need in this field.

SGLT1 as an adverse prognostic factor in invasive ductal carcinoma of the breast

PURPOSE

Sodium/glucose cotransporter (SGLT) 1 and 2 expression in carcinoma cells was recently examined, but their association with the clinicopathological factors of the patients and their biological effects on breast carcinoma cells have remained remain virtually unknown. Therefore, in this study, we explored the expression status of SGLT1 and SGLT2 in breast cancer patients and examined the effects of SGLT1 inhibitors on breast carcinoma cells in vitro.

METHODS

SGLT1 and SGLT2 were immunolocalized and we first correlated the findings with clinicopathological factors of the patients. We then administered mizagliflozin and KGA-2727, SGLT1 specific inhibitors to MCF-7 and MDA-MB-468 breast carcinoma cell lines, and their growth-inhibitory effects were examined. Protein arrays were then used to further explore their effects on the growth factors.

RESULTS

The SGLT1 high group had significantly worse clinical outcome including both overall survival and disease-free survival than low group. SGLT2 status was not significantly correlated with clinical outcome of the patients. Both mizagliflozin and KGA-2727 inhibited the growth of breast cancer cell lines. Of particular interest, mizagliflozin inhibited the proliferation of MCF-7 cells, even under very low glucose conditions. Mizagliflozin downregulated vascular endothelial growth factor receptor 2 phosphorylation.

CONCLUSION

High SGLT1 expression turned out as an adverse clinical prognostic factor in breast cancer patient. This is the first study demonstrating that SGLT1 inhibitors suppressed breast carcinoma cell proliferation. These results indicated that SGLT1 inhibitors could be used as therapeutic agents for breast cancer patients with aggressive biological behaviors.

DCIS and LCIS: Are the Risk Factors for Developing In Situ Breast Cancer Different?

Ductal carcinoma in situ (DCIS) is widely accepted as a precursor of invasive ductal carcinoma (IDC). Lobular carcinoma in situ (LCIS) is considered a risk factor for invasive lobular carcinoma (ILC), and it is unclear whether LCIS is also a precursor. Therefore, it would be expected that similar risk factors predispose to both DCIS and IDC, but not necessarily LCIS and ILC. This study examined associations with risk factors using data from 3075 DCIS cases, 338 LCIS cases, and 1584 controls aged 35-60, recruited from the UK-based GLACIER and ICICLE case-control studies between 2007 and 2012. Analysis showed that breastfeeding in parous women was protective against DCIS and LCIS, which is consistent with research on invasive breast cancer (IBC). Additionally, long-term use of HRT in post-menopausal women increased the risk of DCIS and LCIS, with a stronger association in LCIS, similar to the association with ILC. Contrary to findings with IBC, parity and the number of births were not protective against DCIS or LCIS, while oral contraceptives showed an unexpected protective effect. These findings suggest both similarities and differences in risk factors for DCIS and LCIS compared to IBC and that there may be justification for increased breast surveillance in post-menopausal women taking long-term HRT.

Identifying recurrences and metastasis after ductal carcinoma in situ (DCIS) of the breast

Ductal carcinoma in situ (DCIS) of the breast is a non-invasive tumour that has the potential to progress to invasive ductal carcinoma (IDC). Thus, it represents a treatment dilemma: alone it does not present a risk to life, however, left untreated it may progress to a life-threatening condition. Current clinico-pathological features cannot accurately predict which patients with DCIS have invasive potential, and therefore clinicians are unable to quantify the risk of progression for an individual patient. This leads to many women being over-treated, while others may not receive sufficient treatment to prevent invasive recurrence. A better understanding of the molecular features of DCIS, both tumour-intrinsic and the microenvironment, could offer the ability to better predict which women need aggressive treatment, and which can avoid therapies carrying significant side-effects and such as radiotherapy. In this review, we summarise the current knowledge of DCIS, and consider future research directions.

Accurate genome-wide genotyping from archival tissue to explore the contribution of common genetic variants to pre-cancer outcomes

PURPOSE

The contribution of common genetic variants to pre-cancer progression is understudied due to long follow-up time, rarity of poor outcomes and lack of available germline DNA collection. Alternatively, DNA from diagnostic archival tissue is available, but its somatic nature, limited quantity and suboptimal quality would require an accurate cost-effective genome-wide germline genotyping methodology.

EXPERIMENTAL DESIGN

Blood and tissue DNA from 10 individuals were used to benchmark the accuracy of Single Nucleotide Polymorphisms (SNP) genotypes, Polygenic Risk Scores (PRS) or HLA haplotypes using low-coverage whole-genome sequencing (lc-WGS) and genotype imputation. Tissue-derived PRS were further evaluated for 36 breast cancer patients (11.7 years median follow-up time) diagnosed with DCIS and used to model the risk of Breast Cancer Subsequent Events (BCSE).

RESULTS

Tissue-derived germline DNA profiling resulted in accurate genotypes at common SNPs (blood correlation r2 > 0.94) and across 22 disease-related polygenic risk scores (PRS, mean correlation r = 0.93). Imputed Class I and II HLA haplotypes were 96.7% and 82.5% concordant with clinical-grade blood HLA haplotypes, respectively. In DCIS patients, tissue-derived PRS was significantly associated with BCSE (HR = 2, 95% CI 1.2-3.8). The top and bottom decile patients had an estimated 28% and 5% chance of BCSE at 10 years, respectively.

CONCLUSIONS

Archival tissue DNA germline profiling using lc-WGS and imputation, represents a cost and resource-effective alternative in the retrospective design of long-term disease genetic studies. Initial results in breast cancer suggest that common risk variants contribute to pre-cancer progression.

Establishment of a 3D co‐culture model to investigate the role of primary fibroblasts in ductal carcinoma in situ of the breast

BACKGROUND

Ductal carcinoma in situ (DCIS) is a precursor form of breast cancer. 13%-50% of these lesions will progress to invasive breast cancer, but the individual progression risk cannot be estimated. Therefore, all patients receive the same therapy, resulting in potential overtreatment of a large proportion of patients.

AIMS

The role of the tumor microenvironment (TME) and especially of fibroblasts appears to be critical in DCIS development and a better understanding of their role may aid individualized treatment.

METHODS AND RESULTS

Primary fibroblasts isolated from benign or malignant punch biopsies of the breast and MCF10DCIS.com cells were seeded in a 3D cell culture system. The fibroblasts were cultured in a type I collagen layer beneath a Matrigel layer with MCF10DCIS.com cells. Dye-quenched (DQ) fluorescent collagen I and IV were used in collagen and Matrigel layer respectively to demonstrate proteolysis. Confocal microscopy was performed on day 2, 7, and 14 to reveal morphological changes, which could indicate the transition to an invasive phenotype. MCF10DCIS.com cells form smooth, round spheroids in co-culture with non-cancer associated fibroblasts (NAFs). Spheroids in co-culture with tumor-associated fibroblasts (TAFs) appear irregularly shaped and with an uneven surface; similar to spheroids formed from invasive cells. Therefore, these morphological changes represent the progression of an in situ to an invasive phenotype. In addition, TAFs show a higher proteolytic activity compared to NAFs. The distance between DCIS cells and fibroblasts decreases over time.

CONCLUSION

The TAFs seem to play an important role in the progression of DCIS to invasive breast cancer. The better characterization of the TME could lead to the identification of DCIS lesions with high or low risk of progression. This could enable personalized oncological therapy, prevention of overtreatment and individualized hormone replacement therapy after DCIS.

Learning to distinguish progressive and non-progressive ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) is a non-invasive breast neoplasia that accounts for 25% of all screen-detected breast cancers diagnosed annually. Neoplastic cells in DCIS are confined to the ductal system of the breast, although they can escape and progress to invasive breast cancer in a subset of patients. A key concern of DCIS is overtreatment, as most patients screened for DCIS and in whom DCIS is diagnosed will not go on to exhibit symptoms or die of breast cancer, even if left untreated. However, differentiating low-risk, indolent DCIS from potentially progressive DCIS remains challenging. In this Review, we summarize our current knowledge of DCIS and explore open questions about the basic biology of DCIS, including those regarding how genomic events in neoplastic cells and the surrounding microenvironment contribute to the progression of DCIS to invasive breast cancer. Further, we discuss what information will be needed to prevent overtreatment of indolent DCIS lesions without compromising adequate treatment for high-risk patients.

Genomic analysis defines clonal relationships of ductal carcinoma in situ and recurrent invasive breast cancer

Ductal carcinoma in situ (DCIS) is the most common form of preinvasive breast cancer and, despite treatment, a small fraction (5-10%) of DCIS patients develop subsequent invasive disease. A fundamental biologic question is whether the invasive disease arises from tumor cells in the initial DCIS or represents new unrelated disease. To address this question, we performed genomic analyses on the initial DCIS lesion and paired invasive recurrent tumors in 95 patients together with single-cell DNA sequencing in a subset of cases. Our data show that in 75% of cases the invasive recurrence was clonally related to the initial DCIS, suggesting that tumor cells were not eliminated during the initial treatment. Surprisingly, however, 18% were clonally unrelated to the DCIS, representing new independent lineages and 7% of cases were ambiguous. This knowledge is essential for accurate risk evaluation of DCIS, treatment de-escalation strategies and the identification of predictive biomarkers.

The pathologic diagnosis of carcinoma in various tissues

Carcinoma is defined as cancer arising from the epithelial cells that line an organ or tissue. The most common carcinoma in males arises in the prostate and breast in females; while the most significant cause of cancer related mortality in the United States is carcinoma of the lung. Cancers typically begin as a clonal proliferation of cells that have acquired distinct mutations, which then progress to invasive carcinoma as the cells breach the underlying basement membrane associated with the tissue of origin. This transition to invasive carcinoma carries with it the potential to invade blood vessels or lymphatic channels and metastasize to lymph nodes or distant tissues resulting in increased morbidity and mortality. The histologic diagnosis of carcinoma is rendered based on both the cytologic and architectural features of the tumor, as well as the location of the proliferating cells and the interaction with the surrounding stromal elements.

A Swedish Genome-Wide Haplotype Association Analysis Identifies a Novel Breast Cancer Susceptibility Locus in 8p21.2 and Characterizes Three Loci on Chromosomes 10, 11 and 16

(1) Background: The heritability of breast cancer is partly explained but much of the genetic contribution remains to be identified. Haplotypes are often used as markers of ethnicity as they are preserved through generations. We have previously demonstrated that haplotype analysis, in addition to standard SNP association studies, could give novel and more detailed information on genetic cancer susceptibility. (2) Methods: In order to examine the association of a SNP or a haplotype to breast cancer risk, we performed a genome wide haplotype association study, using sliding window analysis of window sizes 1−25 and 50 SNPs, in 3200 Swedish breast cancer cases and 5021 controls. (3) Results: We identified a novel breast cancer susceptibility locus in 8p21.1 (OR 2.08; p 3.92 × 10−8), confirmed three known loci in 10q26.13, 11q13.3, 16q12.1-2 and further identified novel subloci within these three loci. Altogether 76 risk SNPs, 3302 risk haplotypes of window size 2−25 and 113 risk haplotypes of window size 50 at p < 5 × 10−8 on chromosomes 8, 10, 11 and 16 were identified. In the known loci haplotype analysis reached an OR of 1.48 in overall breast cancer and in familial cases OR 1.68. (4) Conclusions: Analyzing haplotypes, rather than single variants, could detect novel susceptibility loci even in small study populations but the method requires a fairly homogenous study population.

Generation of ductal organoids from normal mammary luminal cells reveals invasive potential

Here we present an experimental model for human luminal progenitor cells that enables single, primary cells isolated from normal tissue to generate complex branched structures resembling the ductal morphology of low-grade carcinoma of no special type. Thereby, we find that ductal structures are generated through invasive branching morphogenesis via matrix remodeling and identify reduced actomyosin contractility as a prerequisite for invasion. In addition, we show that knockout of E-cadherin causes a dissolution of duct formation as observed in invasive lobular carcinoma, a subtype of invasive carcinomas where E-cadherin function is frequently lost. Thus, our model shows that invasive capacity can be elicited from normal luminal cells in specific environments, which results in low-grade no special type morphology. This assay offers a platform to investigate the dynamics of luminal cell invasion and unravel the impact of genetic and non-genetic aberrations on invasive morphology. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Polygenic Breast Cancer Risk for Women Veterans in the Million Veteran Program

Accurate breast cancer (BC) risk assessment allows personalized screening and prevention. Prospective validation of prediction models is required before clinical application. Here, we evaluate clinical- and genetic-based BC prediction models in a prospective cohort of women from the Million Veteran Program.

MATERIALS AND METHODS

Clinical BC risk prediction models were validated in combination with a genetic polygenic risk score of 313 (PRS313) single-nucleotide polymorphisms in genetic females without prior BC diagnosis (n = 35,130, mean age 49 years) with 30% non-Hispanic African ancestry (AA). Clinical risk models tested were Breast and Prostate Cancer Cohort Consortium, literature review, and Breast Cancer Risk Assessment Tool, and implemented with or without PRS313. Prediction accuracy and association with incident breast cancer was evaluated with area under the receiver operating characteristic curve (AUC), hazard ratios, and proportion with high absolute lifetime risk.

RESULTS

Three hundred thirty-eight participants developed incident breast cancers with a median follow-up of 3.9 years (2.5 cases/1,000 person-years), with 196 incident cases in women of European ancestry and 112 incident cases in AA women. Individualized Coherent Absolute Risk Estimator-literature review in combination with PRS313 had an AUC of 0.708 (95% CI, 0.659 to 0.758) in women with European or non-African ancestries and 0.625 (0.539 to 0.711) in AA women. Breast Cancer Risk Assessment Tool with PRS313 had an AUC of 0.695 (0.62 to 0.729) in European or non-AA and 0.675 (0.626 to 0.723) in AA women. Incorporation of PRS313 with clinical models improved prediction in European but not in AA women. Models estimated up to 9% of European and 18% of AA women with absolute lifetime risk > 20%.

CONCLUSION

Clinical and genetic BC risk models predict incident BC in a large prospective multiracial cohort; however, more work is needed to improve genetic risk estimation in AA women.

Genome-wide Copy-number Alterations in Circulating Tumor DNA as a Novel Biomarker for Patients with High-grade Serous Ovarian Cancer

PURPOSE

High-grade serous epithelial ovarian cancer (HGS-EOC) is defined by high levels of somatic copy-number alterations (SCNA) with marked spatial and temporal tumor heterogeneity. Biomarkers serving to monitor drug response and detect disease recurrence are lacking, a fact which reflects an unmet clinical need.

EXPERIMENTAL DESIGN

A total of 185 plasma samples and 109 matched tumor biopsies were collected from 46 patients with HGS-EOC, and analyzed by shallow whole-genome sequencing (sWGS). The percentage of tumor fraction (TF) in the plasma was used to study the biological features of the disease at the time of diagnosis (T0) and correlated with patients' survival. Longitudinal analysis of TF was correlated with CA-125 levels and radiological images to monitor disease recurrence.

RESULTS

Gain in the clonal regions, 3q26.2 and 8q24.3, was observed in the 87.8% and 78.05% of plasma samples, suggesting that plasma sWGS mirrors solid biopsies. At T0, multivariate analysis revealed that plasma TF levels were an independent prognostic marker of relapse (P < 0.022). After platinum (Pt)-based treatment, circulating tumor DNA (ctDNA) analysis showed a change in the heterogeneous pattern of genomic amplification, including an increased frequency of amplification, compared with before Pt-based treatment in the 19p31.11 and 19q13.42 regions. TF in serially collected ctDNA samples outperformed CA-125 in anticipating clinical and radiological progression by 240 days (range, 37-491).

CONCLUSIONS

Our results support the notion that sWGS is an inexpensive and useful tool for the genomic analysis of ctDNA in patients with HGS-EOC to monitor disease evolution and to anticipate relapse better than serum CA-125, the routinely used clinical biomarker.See related commentary by Dhani, p. 2372.

High EZH2 expression in ductal carcinoma in situ diagnosed on breast core needle biopsy is an independent predictive factor for upgrade on surgical excision

PURPOSE

Approximately 25 % of DCIS diagnosed on breast core needle biopsy (CNB) is upgraded to invasive carcinoma on surgical excision. Risk factors to predict the upgrade on excision are not well established, leading many patients to be over or under-treated. EZH2 was shown to be associated with aggressive behavior of cancer from many sites, including breast cancer. We aimed to analyze EZH2 expression and tumor infiltrating lymphocytes (TILs) in DCIS as predictive factors for an upgrade on excision.

METHODS

We assessed EZH2 expression in 34 DCIS cases diagnosed on CNB and upgraded to invasive carcinoma on excision. Then, we compared these cases with 60 control cases that were not upgraded on excision. A staining score for DCIS (0-12) was obtained by multiplying the staining intensity (0-3) and the percentage of positive cells (1-4). The nuclear staining score ≥6 was considered as 'high' expression.

RESULTS

46 of 94 (49 %) DCIS on CNB showed high EZH2 expression. EZH2 expression was directly correlated with TILs density, nuclear grade, HER2 expression, Ki-67 index and negative ER status. On univariate analysis, upgrade on excision was associated with high EZH2 expression, high TILs density, negative ER status and high Ki-67 index. Multivariate analysis revealed the high EZH2 expression as the only independent predictive factor for upgrade on excision.

CONCLUSIONS

Our study revealed the high EZH2 expression as the only independent predictive factor for an upgrade on excision. Future studies should focus on the evaluation of EZH2 expression in tumor-microenvironment interaction in terms of diagnostic, treatment and prognostic purposes.

Risk of invasive breast cancer in relatives of patients with breast carcinoma in situ: a prospective cohort study

BACKGROUND

Wide implementation of mammography screening has resulted in increased numbers of women diagnosed with breast carcinoma in situ. We aimed to determine the risk of invasive breast cancer in relatives of patients with breast carcinoma in situ in comparison to the risk in relatives of patients with invasive breast cancer.

METHODS

We analyzed the occurrence of cancer in a nationwide cohort including all 5,099,172 Swedish women born after 1931 with at least one known first-degree relative. This was a record linkage study of Swedish family cancer datasets, including cancer registry data collected from January 1, 1958, to December 31, 2015. We calculated standardized incidence ratios (SIRs) and 10-year cumulative risk of breast cancer diagnosis for women with a family history of in situ and invasive breast cancer.

RESULTS

Having one first-degree relative with breast carcinoma in situ was associated with 50% increased risk of invasive breast cancer (SIR = 1.5, 95% CI 1.4-1.7) when compared to those who had no family history of invasive breast cancer or breast carcinoma in situ in either first- or second-degree relatives. Similarly, having one first-degree relative with invasive breast cancer was associated with 70% (1.7, 1.7-1.8) increased risk. The 10-year cumulative risk for women at age 50 with a relative with breast carcinoma in situ was 3.5% (2.9-3.9%) and was not significantly different from 3.7% (3.6-3.8%) risk for 50-year-old women with a relative with invasive breast cancer (95% confidence intervals overlapped).

CONCLUSIONS

The risk of invasive breast cancer for women with a family history of breast carcinoma in situ was comparable to that for women with a family history of invasive breast cancer. Therefore, family history of breast carcinoma in situ should not be overlooked in recommendations for breast cancer prevention for women with a family history of breast cancer.

Validation of the BOADICEA model and a 313-variant polygenic risk score for breast cancer risk prediction in a Dutch prospective cohort

PURPOSE

We evaluated the performance of the recently extended Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA version 5) in a Dutch prospective cohort, using a polygenic risk score (PRS) based on 313 breast cancer (BC)-associated variants (PRS313) and other, nongenetic risk factors.

METHODS

Since 1989, 6522 women without BC aged 45 or older of European descent have been included in the Rotterdam Study. The PRS313 was calculated per 1 SD in controls from the Breast Cancer Association Consortium (BCAC). Cox regression analysis was performed to estimate the association between the PRS313 and incident BC risk. Cumulative 10-year risks were calculated with BOADICEA including different sets of variables (age, risk factors and PRS313). C-statistics were used to evaluate discriminative ability.

RESULTS

In total, 320 women developed BC. The PRS313 was significantly associated with BC (hazard ratio [HR] per SD of 1.56, 95% confidence interval [CI] [1.40-1.73]). Using 10-year risk estimates including age and the PRS313, other risk factors improved the discriminatory ability of the BOADICEA model marginally, from a C-statistic of 0.636 to 0.653.

CONCLUSIONS

The effect size of the PRS313 is highly reproducible in the Dutch population. Our results validate the BOADICEA v5 model for BC risk assessment in the Dutch general population.

Characterization of organoid cultured human breast cancer

Organoid cultures are increasingly used to model human cancers experimentally with a view to tailoring personalized medicine and predicting drug responses. Breast cancer is no exception, but in particular, primary breast cancer poses some inherent difficulties due to the frequent presence of residual non-malignant cells in the biopsies. We originally developed an assay for the distinction between malignant and non-malignant structures in primary breast cancer organoid cultures (Petersen et al., Proc Natl Acad Sci (USA) 89(19):9064–8, 1992). Here, we apply this assay to assess the frequency of normal-like organoids in primary breast carcinoma cultures and the cellular composition as a consequence of passaging. We find that in consecutively collected samples of primary human breast cancers, residual non-malignant tissues were observed histologically in five out of ten biopsies. Based on relevant morphogenesis and correct polarization as recorded by expression in luminal epithelial cells of mucin 1 (Muc1), occludin, and keratin 19 (K19) and expression in basal cells of integrin β4, p63, and K14, non-malignant organoids were present in all primary human breast cancer-derived cultures. Furthermore, passaging in a contemporary culture medium was in favor of the selective expansion of basal-like cells. We conclude that organoid cultures of human breast cancers are most representative of the tissue origin in primary culture.

The Variant at TGFBRAP1 but Not TGFBR2 Is Associated with Antituberculosis Drug-Induced Liver Injury

Background

TGFBRAP1 and TGFBR2 play important roles in the TGF-β/smad signalling pathway and may disturb liver homeostasis by regulating liver injury and renewal. However, little is known about the association between their genetic polymorphisms and antituberculosis drug-induced liver injury (ATDILI), so we explored the association between their variants and the susceptibility to ATDILI.

Materials and Methods

A total of 746 tuberculosis patients were prospectively enrolled, and fifteen selected SNPs were genotyped. The allele, genotype, and genetic model frequencies of the variants were compared between patients with or without ATDILI, as well as the joint effect analysis of SNP-SNP interactions. The odds ratio (OR) with the corresponding 95% confidence interval (CI) was calculated.

Results

The A variant at rs17687727 was significantly associated with an increased risk for ATDILI (OR 1.55; 95% CI: 1.08–2.22; p = 0.016), which is consistent with the results in the additive and dominant models. Other allele, genotype, and genetic model frequencies were similar in the two groups for the other fourteen SNPs (all p > 0.05).

Conclusion

Our study first implied that the A variant of rs17687727 in TGFBRAP1 influenced the susceptibility to ATDILI in first-line antituberculosis combination treatment in the Han Chinese population in a dependent manner.

Frequency of pathogenic germline variants in BRCA1, BRCA2, PALB2, CHEK2 and TP53 in ductal carcinoma in situ diagnosed in women under the age of 50 years

INTRODUCTION

Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive ductal breast cancer, and approximately 20% of screen-detected tumours are pure DCIS. Most risk factors for breast cancer have similar associations with DCIS and IDC; however, there is limited data on the prevalence of the known high and moderate penetrance breast cancer predisposition genes in DCIS and which women with DCIS should be referred for genetic screening. The aim of this study was to assess the frequency of germline variants in BRCA2, BRCA1, CHEK2, PALB2 and TP53 in DCIS in women aged less than 50 years of age.

METHODS

After DNA extraction from the peripheral blood, Access Array technology (Fluidigm) was used to amplify all exons of these five known breast cancer predisposition genes using a custom made targeted sequencing panel in 655 cases of pure DCIS presenting in women under the age of 50 years together with 1611 controls.

RESULTS

Case-control analysis revealed an excess of pathogenic variants in BRCA2 (OR = 27.96, 95%CI 6.56-119.26, P = 2.0 × 10^-10) and CHEK2 (OR = 8.04, 95%CI 2.93-22.05, P = 9.0 × 10^-6), with weaker associations with PALB2 (P = 0.003), BRCA1 (P = 0.007) and TP53 (P = 0.02). For oestrogen receptor (ER)-positive DCIS the frequency of pathogenic variants was 9% under the age of 50 (14% with a family history of breast cancer) and 29% under the age of 40 (42% with a family history of breast cancer). For ER-negative DCIS, the frequency was 9% (16% with a family history of breast cancer) and 8% (11% with a family history of breast cancer) under the ages of 50 and 40, respectively.

CONCLUSIONS

This study has shown that breast tumourigenesis in women with pathogenic variants in BRCA2, CHEK2, PALB2, BRCA1 and TP53 can involve a DCIS precursor stage and that the focus of genetic testing in DCIS should be on women under the age of 40 with ER-positive DCIS.

In Vitro Models for Studying Invasive Transitions of Ductal Carcinoma In Situ

About one fourth of all newly identified cases of breast carcinoma are diagnoses of breast ductal carcinoma in situ (DCIS). Since we cannot yet distinguish DCIS cases that would remain indolent from those that may progress to life-threatening invasive ductal carcinoma (IDC), almost all women undergo aggressive treatment. In order to allow for more rational individualized treatment, we and others are developing in vitro models to identify and validate druggable pathways that mediate the transition of DCIS to IDC. These models range from conventional two-dimensional (2D) monolayer cultures on plastic to 3D cultures in natural or synthetic matrices. Some models consist solely of DCIS cells, either cell lines or primary cells. Others are co-cultures that include additional cell types present in the normal or cancerous human breast. The 3D co-culture models more accurately mimic structural and functional changes in breast architecture that accompany the transition of DCIS to IDC. Mechanistic studies of the dynamic and temporal changes associated with this transition are facilitated by adapting the in vitro models to engineered microfluidic platforms. Ultimately, the goal is to create in vitro models that can serve as a reproducible preclinical screen for testing therapeutic strategies that will reduce progression of DCIS to IDC. This review will discuss the in vitro models that are currently available, as well as the progress that has been made using them to understand DCIS pathobiology.

Ductal Carcinoma In Situ

Ductal carcinoma in situ has been stable in incidence for a decade and has an excellent prognosis. Breast conservation therapy is safe and effective for most patients. Adjuvant whole breast radiation therapy is recommended to reduce the risk of local recurrence. Accelerated partial breast irradiation is a promising alternative to decrease toxicity and improve cosmetic results. Adjuvant hormonal therapy can reduce local recurrence, but should be used cautiously. Future directions in management include developing predictive tools for guidance for use of adjuvant therapy and selecting low-risk patients with ductal carcinoma in situ in whom surgery may be safely omitted.

A comprehensive analysis of polymorphic variants in steroid hormone and insulin-like growth factor-1 metabolism and risk of in situ breast cancer: Results from the Breast and Prostate Cancer Cohort Consortium

We assessed the association between 1,414 single nucleotide polymorphisms (SNPs) in genes involved in synthesis and metabolism of steroid hormones and insulin-like growth factor 1, and risk of breast cancer in situ (BCIS), with the aim of determining whether any of these were disease specific. This was carried out using 1,062 BCIS cases and 10,126 controls as well as 6,113 invasive breast cancer cases from the Breast and Prostate Cancer Cohort Consortium (BPC3). Three SNPs showed at least one nominally significant association in homozygous minor versus homozygous major models. ACVR2A-rs2382112 (OR_hom  = 3.05, 95%CI = 1.72-5.44, P_hom  = 1.47 × 10^-4 ), MAST2-rs12124649 (OR_hom  = 1.73, 95% CI =1.18-2.54, P_hom  = 5.24 × 10^-3 ), and INSR-rs10500204 (OR_hom  = 1.96, 95% CI = 1.44-2.67, P_hom =1.68 × 10^-5 ) were associated with increased risk of BCIS; however, only the latter association was significant after correcting for multiple testing. Furthermore, INSR-rs10500204 was more strongly associated with the risk of BCIS than invasive disease in case-only analyses using the homozygous minor versus homozygous major model (OR_hom  = 1.78, 95% CI = 1.30-2.44, P_hom  = 3.23 × 10^-4 ). The SNP INSR-rs10500204 is located in an intron of the INSR gene and is likely to affect binding of the promyelocytic leukemia (PML) protein. The PML gene is known as a tumor suppressor and growth regulator in cancer. However, it is not clear on what pathway the A-allele of rs10500204 could operate to influence the binding of the protein. Hence, functional studies are warranted to investigate this further.

Evaluation of three polygenic risk score models for the prediction of breast cancer risk in Singapore Chinese

Genome-wide association studies (GWAS) have proven highly successful in identifying single nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk. The majority of these studies are on European populations, with limited SNP association data in other populations. We genotyped 51 GWAS-identified SNPs in two independent cohorts of Singaporean Chinese. Cohort 1 comprised 1294 BC cases and 885 controls and was used to determine odds ratios (ORs); Cohort 2 had 301 BC cases and 243 controls for deriving polygenic risk scores (PRS). After age-adjustment, 11 SNPs were found to be significantly associated with BC risk. Five SNPs were present in <1% of Cohort 1 and were excluded from further PRS analysis. To assess the cumulative effect of the remaining 46 SNPs on BC risk, we generated three PRS models: Model-1 included 46 SNPs; Model-2 included 11 statistically significant SNPs; and Model-3 included the SNPs in Model-2 but excluded SNPs that were in strong linkage disequilibrium with the others. Across Models-1, -2 and -3, women in the highest PRS quartile had the greatest ORs of 1.894 (95% CI = 1.157–3.100), 2.013 (95% CI = 1.227–3.302) and 1.751 (95% CI = 1.073–2.856) respectively, suggesting a direct correlation between PRS and BC risk. Given the potential of PRS in BC risk stratification, our findings suggest the need to tailor the selection of SNPs to be included in an ethnic-specific PRS model.

Family History and Risk of Second Primary Breast Cancer after In Situ Breast Carcinoma

Background: Incidence rates of in situ breast carcinomas have increased due to widespread adoption of mammography. Very little is known about why some women with in situ breast cancer later develop second primary breast cancers.Methods: In this population-based nested case-control study among in situ breast cancer survivors, including 539 cases with a second primary breast cancer and 994 matched controls, we evaluated the association between first-degree family history of breast cancer and risk of developing a second primary breast cancer.Results: First-degree family history of breast cancer was associated with an increased risk of developing a second primary breast cancer among women with a previous in situ breast cancer [odds ratio (OR) = 1.33, 95% confidence interval (CI), 1.05-1.69] and those with two or more affected first-degree relatives had an even higher risk (OR = 1.94; 95% CI, 1.15-3.28). Those whose relative was diagnosed at less than 50 years old were more likely to develop a second primary breast cancer (OR = 1.78; 95% CI, 1.24-2.57). No difference in risks associated with number or age of affected relatives was observed by menopausal status.Conclusions: Results from this study suggest that first-degree family history of breast cancer may be an important risk factor for development of a second primary breast cancer among women with a previous in situ breast cancer.Impact: Given the growing population of in situ breast cancer survivors, a better understanding of risk factors associated with development of a second primary breast cancer is needed to further understand risk. Cancer Epidemiol Biomarkers Prev; 27(3); 315-20. ©2018 AACR.

Discoidin domain receptor 1: New star in cancer-targeted therapy and its complex role in breast carcinoma

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase activated by various types of collagens that performs a critical role in cell attachment, migration, survival and proliferation. The functions of DDR1 in various types of tumor have been studied extensively. However, in breast carcinoma, the roles of collagen-evoked DDR1 remain ill defined. Although a number of studies have reported that DDR1 promotes apoptosis and inhibits migration in breast carcinoma, it has also been reported to be associated with tumor cell survival, chemoresistance to genotoxic drugs and the facilitation of invasion. The present review summarizes current progress and the complex effects of DDR1 in the field of breast carcinoma, and presents DDR1 as a promising therapeutic target.

Comparison of the association of mammographic density and clinical factors with ductal carcinoma in situ versus invasive ductal breast cancer in Korean women

BACKGROUND

In spite of the increasing incidence of in situ breast cancer, the information about the risk factors of in situ breast cancer (DCIS) is scarce as compared to the information available for invasive ductal breast cancer (IDC), with inconsistent findings regarding the difference in risk factors between DCIS and IDC.

METHODS

We enrolled 472 women with IDC and 90 women with DCIS and 1088 controls matching for age and menopausal status. Information on risk factors was collected through self-administered questionnaire. Percent mammographic dense area (PDA), absolute mammographic dense area (ADA), and nondense area were assessed using a computer-assisted thresholding technique. Odds ratio (OR) and 95% confidence intervals (CI) were estimated by conditional logistic regression model with adjustment for covariates.

RESULTS

Later age at menarche and regular physical exercise were associated with decreased risk of IDC, whereas alcohol consumption, previous benign breast disease, and family history of breast cancer were associated with increased risk of IDC. For DCIS, previous benign breast disease and alcohol consumption were associated with the increased risk, and regular physical exercise was associated with decreased risk. Increase of ADA by 1-quartile level and PDA increase by 10% were associated with 1.10 (95% CI: 1.01, 1.21) and 1.10 (95% CI: 1.01, 1.19) times greater risk of IDC, respectively. The increase of ADA by 1-quartile level and PDA increase by 10% were associated with 1.17 (95% CI: 0.91, 1.50) times and 1.11 (95% CI:0.90,1.37) times greater risk of DCIS, respectively, but the associations were not statistically significant. There was no significant difference in the association with risk factors and mammographic density measures between IDC and DCIS (P > 0.1).

CONCLUSIONS

Differential associations of DCIS with mammographic density and risk factors as compared with the associations of IDC were not evident. This finding suggests that IDC and DCIS develop through the shared causal pathways.

Evaluating the efficacy of post-surgery adjuvant therapies used for ductal carcinoma in situ patients: a network meta-analysis

OBJECTIVE

Post-surgery adjuvant therapies are very important for patients suffering from ductal carcinoma in situ (DCIS). In this study we conducted a network meta-analysis (NMA) to evaluate the efficacy of different post-surgery adjuvant therapies including tamoxifen, anastrozole and radiation therapy (RT) and their combinations (RT+ tamoxifen and RT+ anastrozole).

METHODS

We searched several databases, including Embase, MEDLINE / PUBMED, Cochrane Library, and Science Citation Index, for relevant studies. We then extracted the data from eligible studies in order to perform our NMA. We measured the comparative efficacy of each treatment option based on the calculated odds ratios (ORs) and the corresponding 95% credibility interval (95%CrI) for each treatment option. We calculated the surfaces under the cumulative ranking curves (SUCRA) in order to rank the therapies according to their different outcomes.

RESULTS

In this study, local recurrence (LC) was chosen as the primary outcome. Metastasis, contralateral-breast cancer (CBC), ipsilateral-breast cancer (IBC) and death were secondary outcomes. Patients treated with RT and RT + tamoxifen exhibited a lower risk of LC compared with control group (OR=0.54, 95%CrI: 0.40-0.73; OR=0.41, 95%CrI: 0.19-0.90). Patients treated by RT and RT + tamoxifen also exhibited a significantly lower risk of IBC compared with control group (OR=0.55, 95%CrI: 0.37-0.82; OR=0.42, 95%CrI: 0.18-0.99). Results from the SUCRA indicated that RT + anastrozole and RT + tamoxifen were potentially the best adjuvant treatments for patients with DCIS.

CONCLUSIONS

In conclusion, the RT + anastrozole and RT + tamoxifen are recommended for their performance and effectiveness.

Precancer Atlas to Drive Precision Prevention Trials

Cancer development is a complex process driven by inherited and acquired molecular and cellular alterations. Prevention is the holy grail of cancer elimination, but making this a reality will take a fundamental rethinking and deep understanding of premalignant biology. In this Perspective, we propose a national concerted effort to create a Precancer Atlas (PCA), integrating multi-omics and immunity - basic tenets of the neoplastic process. The biology of neoplasia caused by germline mutations has led to paradigm-changing precision prevention efforts, including: tumor testing for mismatch repair (MMR) deficiency in Lynch syndrome establishing a new paradigm, combinatorial chemoprevention efficacy in familial adenomatous polyposis (FAP), signal of benefit from imaging-based early detection research in high-germline risk for pancreatic neoplasia, elucidating early ontogeny in BRCA1-mutation carriers leading to an international breast cancer prevention trial, and insights into the intricate germline-somatic-immunity interaction landscape. Emerging genetic and pharmacologic (metformin) disruption of mitochondrial (mt) respiration increased autophagy to prevent cancer in a Li-Fraumeni mouse model (biology reproduced in clinical pilot) and revealed profound influences of subtle changes in mt DNA background variation on obesity, aging, and cancer risk. The elaborate communication between the immune system and neoplasia includes an increasingly complex cellular microenvironment and dynamic interactions between host genetics, environmental factors, and microbes in shaping the immune response. Cancer vaccines are in early murine and clinical precancer studies, building on the recent successes of immunotherapy and HPV vaccine immune prevention. Molecular monitoring in Barrett's esophagus to avoid overdiagnosis/treatment highlights an important PCA theme. Next generation sequencing (NGS) discovered age-related clonal hematopoiesis of indeterminate potential (CHIP). Ultra-deep NGS reports over the past year have redefined the premalignant landscape remarkably identifying tiny clones in the blood of up to 95% of women in their 50s, suggesting that potentially premalignant clones are ubiquitous. Similar data from eyelid skin and peritoneal and uterine lavage fluid provide unprecedented opportunities to dissect the earliest phases of stem/progenitor clonal (and microenvironment) evolution/diversity with new single-cell and liquid biopsy technologies. Cancer mutational signatures reflect exogenous or endogenous processes imprinted over time in precursors. Accelerating the prevention of cancer will require a large-scale, longitudinal effort, leveraging diverse disciplines (from genetics, biochemistry, and immunology to mathematics, computational biology, and engineering), initiatives, technologies, and models in developing an integrated multi-omics and immunity PCA - an immense national resource to interrogate, target, and intercept events that drive oncogenesis. Cancer Res; 77(7); 1510-41. ©2017 AACR.

Genomic approaches to accelerate cancer interception

Although major advances have been reported in the last decade in the treatment of late-stage cancer with targeted and immune-based therapies, there is a crucial unmet need to develop new approaches to improve the prevention and early detection of cancer. Advances in genomics and computational biology offer unprecedented opportunities to understand the earliest molecular events associated with carcinogenesis, enabling novel strategies to intercept the development of invasive cancers. This Series paper will highlight emerging big data genomic approaches with the potential to accelerate advances in cancer prevention, screening, and early detection across various tumour types, and the challenges inherent in the development of these tools for clinical use. Through coordinated multicentre consortia, these genomic approaches are likely to transform the landscape of cancer interception in the coming years.

Cis-eQTL-based trans-ethnic meta-analysis reveals novel genes associated with breast cancer risk

Breast cancer is the most common solid organ malignancy and the most frequent cause of cancer death among women worldwide. Previous research has yielded insights into its genetic etiology, but there remains a gap in the understanding of genetic factors that contribute to risk, and particularly in the biological mechanisms by which genetic variation modulates risk. The National Cancer Institute's "Up for a Challenge" (U4C) competition provided an opportunity to further elucidate the genetic basis of the disease. Our group leveraged the seven datasets made available by the U4C organizers and data from the publicly available UK Biobank cohort to examine associations between imputed gene expression and breast cancer risk. In particular, we used reference datasets describing the breast tissue and whole blood transcriptomes to impute expression levels in breast cancer cases and controls. In trans-ethnic meta-analyses of U4C and UK Biobank data, we found significant associations between breast cancer risk and the expression of RCCD1 (joint p-value: 3.6x10-06) and DHODH (p-value: 7.1x10-06) in breast tissue, as well as a suggestive association for ANKLE1 (p-value: 9.3x10-05). Expression of RCCD1 in whole blood was also suggestively associated with disease risk (p-value: 1.2x10-05), as were expression of ACAP1 (p-value: 1.9x10-05) and LRRC25 (p-value: 5.2x10-05). While genome-wide association studies (GWAS) have implicated RCCD1 and ANKLE1 in breast cancer risk, they have not identified the remaining three genes. Among the genetic variants that contributed to the predicted expression of the five genes, we found 23 nominally (p-value < 0.05) associated with breast cancer risk, among which 15 are not in high linkage disequilibrium with risk variants previously identified by GWAS. In summary, we used a transcriptome-based approach to investigate the genetic underpinnings of breast carcinogenesis. This approach provided an avenue for deciphering the functional relevance of genes and genetic variants involved in breast cancer.

Genome evolution in ductal carcinoma in situ: invasion of the clones

Ductal carcinoma in situ (DCIS) is the most frequently diagnosed early-stage breast cancer. Only a subset of patients progress to invasive ductal carcinoma (IDC), and this presents a formidable clinical challenge for determining which patients to treat aggressively and which patients to monitor without therapeutic intervention. Understanding the molecular and genomic basis of invasion has been difficult to study in DCIS cancers due to several technical obstacles, including low tumour cellularity, lack of fresh-frozen tissues, and intratumour heterogeneity. In this review, we discuss the role of intratumour heterogeneity in the progression of DCIS to IDC in the context of three evolutionary models: independent lineages, evolutionary bottlenecks, and multiclonal invasion. We examine the evidence in support of these models and their relevance to the diagnosis and treatment of patients with DCIS. We also discuss how emerging technologies, such as single-cell sequencing, STAR-FISH, and imaging mass spectrometry, are likely to provide new insights into the evolution of this enigmatic disease. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Identifying progression predictors of breast ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) refers to neoplastic epithelial cells proliferating within the mammary ducts of the breast, which have not breached the basement membrane nor invaded surrounding tissues. Traditional thinking holds that DCIS represents an early step in a linear progression towards invasive ductal carcinoma (IDC). However, as only approximately half of DCIS cases progress to IDC, important questions around the key determinants of malignant progression need to be answered. Recent studies have revealed that molecular differences between DCIS and IDC cells are not found at the genomic level; instead, altered patterns of gene expression and post-translational regulation lead to distinct transcriptomic and proteomic profiles. Therefore, understanding malignant progression will require a different approach that takes into account the diverse tumour cell extrinsic factors driving changes in tumour cell gene expression necessary for the invasive phenotype. Here, we review the roles of the tumour stroma (including mesenchymal cells, immune cells and the extracellular matrix) and myoepithelial cells in malignant progression and make a case for a more integrated approach to the study and assessment of DCIS and its progression, or lack thereof, to invasive disease.

Disease evolution and heterogeneity in bilateral breast cancer

Bilateral breast cancers (BBC) are currently treated as independent tumors arising in the same patient. Herein, we investigated whether BBC indeed evolve independently at the genomic level. We examined paired targeted next generation sequencing genotypes from 155 paraffin tumors corresponding to 76 BBC patients (75 women and one man; 52 concurrent and 24 metachronous), for coding mutations (amino acid changing, minor allele frequency <0.1%) and single nucleotide polymorphism (SNP) zygosity. Germline genotypes were available for 29 patients. Mutations were present in 80 tumors (54/76 patients; 71%), were mostly tumor-private (90%), more frequent in TP53 (19%), PIK3CA (14%), CDH1, GATA3, MLL3. TP53 mutations were more frequent in metachronous tumors (P<0.001); hormone receptor negative (P<0.001); with higher Ki-67 (P=0.002); and, in younger patients (P=0.01). Hypermutated tumors, all TP53 mutated, were diagnosed as the first incidence in 5 patients; their metachronous counterparts were mutation poor without TP53 involvement. Paired tumors shared common mutations at intratumoral frequency >20% in 10/54 comparable BBC (18.5%), 8/10 concurrent. SNP zygosity status was less preserved in metachronous, compared to concurrent disease. Pathogenic germline mutations were present in 10/29 patients, 9 in BRCA1 and one in TP53 (p.Phe341Val, first report in the germline). BBC demonstrated extensive inter- and intra-patient heterogeneity in the present thus far largest series of corresponding paired genotypes. The majority evolve independently and unpredictably, supporting current clinical practice. A considerable minority though, retains clonal origin and may be regarded as a distinct group for therapeutic interventions among concurrent BBC.

Leveraging premalignant biology for immune-based cancer prevention

Prevention is an essential component of cancer eradication. Next-generation sequencing of cancer genomes and epigenomes has defined large numbers of driver mutations and molecular subgroups, leading to therapeutic advances. By comparison, there is a relative paucity of such knowledge in premalignant neoplasia, which inherently limits the potential to develop precision prevention strategies. Studies on the interplay between germ-line and somatic events have elucidated genetic processes underlying premalignant progression and preventive targets. Emerging data hint at the immune system's ability to intercept premalignancy and prevent cancer. Genetically engineered mouse models have identified mechanisms by which genetic drivers and other somatic alterations recruit inflammatory cells and induce changes in normal cells to create and interact with the premalignant tumor microenvironment to promote oncogenesis and immune evasion. These studies are currently limited to only a few lesion types and patients. In this Perspective, we advocate a large-scale collaborative effort to systematically map the biology of premalignancy and the surrounding cellular response. By bringing together scientists from diverse disciplines (e.g., biochemistry, omics, and computational biology; microbiology, immunology, and medical genetics; engineering, imaging, and synthetic chemistry; and implementation science), we can drive a concerted effort focused on cancer vaccines to reprogram the immune response to prevent, detect, and reject premalignancy. Lynch syndrome, clonal hematopoiesis, and cervical intraepithelial neoplasia which also serve as models for inherited syndromes, blood, and viral premalignancies, are ideal scenarios in which to launch this initiative.