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Purpose: HER2 is overexpressed more frequently in ductal carcinoma in situ (DCIS) than in invasive breast cancer but its prognostic significance and predictive role for radiotherapy has not been clearly established. We investigated the prognostic and predictive value of HER2 overexpression in DCIS., Experimental Design: HER2 expression was evaluated by IHC using the HercepTest™ in samples from UK/ANZ DCIS trial participants (n = 755) with IHC 3+ expression categorized as HER2 positive for primary analyses. Sensitivity analyses included HER2 categorization as negative (IHC 0,1+), equivocal (IHC 2+), and positive (IHC 3+) and analyses restricted to a nested case-control component where 181 cases (with recurrence) were matched to 362 controls by treatment arm and age., Results: Two-hundred and forty-five (34.4%) of evaluable 713 samples [181 ipsilateral breast events (IBE)] were HER2 positive. HER2 overexpression was associated with significantly increased risk of IBE [HR = 2.29; 95% confidence interval (95% CI), 1.64-3.14; P < 0.0001] and in situ IBE (DCIS-IBE; HR = 2.90; 95% CI, 1.91-4.40; P < 0.0001), but not of invasive IBE (I-IBE; HR = 1.40; 95% CI, 0.81-2.42; P = 0.23; Pheterogeneity = 0.04). Inclusion of HER2 significantly improved [Δχ2 (1d.f.) 12.25; P = 0.0005] a prognostic model of clinicopathological and treatment variables, HER2 being an independent predictor of IBE (multivariate HR = 1.91; 95% CI, 1.33-2.76; P = 0.0004). Radiotherapy benefit in preventing DCIS-IBE was significantly greater (Pheterogeneity = 0.04) in HER2-positive DCIS (HR = 0.16; 95% CI, 0.07-0.41) compared with HER2-negative DCIS (HR = 0.58; 95% CI, 0.28-1.19)., Conclusions: HER2 overexpression is associated with significantly increased risk of in situ recurrence and is also predictive of radiotherapy benefit, with greater reductions in in situ but not invasive recurrences in HER2-positive DCIS., (©2021 The Authors; Published by the American Association for Cancer Research.)

Purpose: The prognostic value of estrogen receptor (ER)/progesterone receptor (PgR) expression in ductal carcinoma in situ (DCIS) is unclear. We observed multi-clonality when evaluating ER/PgR expression in the UK/ANZ DCIS trial, therefore, we investigated the prognostic role of both uni-clonal and multi-clonal ER/PgR expression in DCIS., Experimental Design: Formalin-fixed paraffin embedded tissues were collected from UK/ANZ DCIS trial participants ( n = 755), and ER/PgR expression was evaluated by IHC in 181 cases (with recurrence) matched to 362 controls by treatment arm and age. Assays were scored by the Allred method and by a newly devised clonal method-analyses categorizing multi-clonal DCIS as ER/PgR-positive as per current practice (Standard) and as ER/PgR-negative (clonal) were performed., Results: ER expression was multi-clonal in 11% (39/356) of ER-positive (70.6%, 356/504) patients. Ipsilateral breast event (IBE) risk was similarly higher in ER-multi-clonal and ER-negative DCIS as compared with DCIS with uni-clonal ER expression. ER-negative DCIS (clonal) had a higher risk of in situ IBE [OR 4.99; 95% confidence interval (CI), 2.66-9.36; P < 0.0001], but the risk of invasive IBE was not significantly higher (OR 1.72; 95% CI, 0.84-3.53; P = 0.14), P heterogeneity = 0.03. ER was an independent predictor in multivariate analyses (OR 2.66; 95% CI, 1.53-4.61). PgR status did not add to the prognostic information provided by ER., Conclusions: ER expression is a strong predictor of ipsilateral recurrence risk in DCIS. ER-positive DCIS with distinct ER-negative clones has a recurrence risk similar to ER-negative DCIS. ER should be routinely assessed in DCIS, and ER scoring should take clonality of expression into account., (©2021 American Association for Cancer Research.)

Background: Tumor stroma, of which fibroblasts are the most abundant cell, resembles a non-healing wound, where a procoagulant environment creates a permissive milieu for cancer growth. We aimed to determine if tumor expression of coagulation factors (procoagulant phenotype), and systemic hypercoagulability, occur at the preinvasive (ductal carcinoma in situ; DCIS) stage and correlate with breast cancer subtype, disease-free survival (DFS), and overall survival (OS)., Methods: In a prospective cohort of early breast cancer (DCIS, n = 76; invasive, n = 248) tumor, normal breast and plasma were examined. Fibroblast and epithelial expression of Tissue Factor (TF), thrombin, PAR1, PAR2, and plasma thrombin-antithrombin (TAT) and D-dimer were correlated with clinicopathological data, and 5-year survival., Results: Fibroblast expression of TF, thrombin, and PAR1 was increased in DCIS and invasive cancer compared to normal breast fibroblasts (P ≤ .003, all). Fibroblast TF, thrombin, PAR1, and PAR2 was increased in cancers with high Ki67, high grade, ER- (vs ER+), and HER2+ (vs HER2-) (all P < .05). On univariate analysis, fibroblast TF expression was inversely associated with DFS (P = .04) and OS (P = .02). D-dimer was higher in node positive (507 (CI: 411-625) ng/mL, n = 68) vs negative patients (428 (CI: 387-472) ng/mL, n = 171, P = .004) and inversely associated with OS (P = .047). On multivariate analysis, plasma TAT was associated with reduced OS (HR 3.26, CI 1.16-3.1, P = .02), with a high plasma TAT (≥3.2 ng/mL) associated with > 3-fold mortality risk compared to low TAT., Conclusion: This demonstrates procoagulant phenotypic changes occur in fibroblasts at the preinvasive stage. Fibroblast procoagulant phenotype is associated with aggressive breast cancer subtypes and reduced survival. Coagulation may be a therapeutic target in breast cancer., (© 2019 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Breast-conserving surgery for ductal carcinoma in situ (DCIS) is often combined with irradiation, reducing recurrence rates to 20% within 10 years; however, there is no change in overall survival. Evidence in the invasive breast indicates that breast cancer stem cells (CSCs) are radiotherapy-resistant and are capable of re-initiating a tumor recurrence; hence, targeting CSCs in high risk DCIS patient may improve survival. HER2 is overexpressed in 20% of DCIS and is known to be highly active in breast CSCs; we therefore investigated the effect of Lapatinib on DCIS CSC activity using 2 in vitro culture systems. Two DCIS cell lines DCIS.com (HER2 normal) and SUM225 (HER2 overexpressed) as well as DCIS cells from patient samples (n = 18) were cultured as mammospheres to assess CSC activity and in differentiated 3D-matrigel culture to determine effects within the non-CSCs. Mammosphere formation was reduced regardless of HER2 status, although this was more marked within the HER2-positive samples. When grown as differentiated DCIS acini in 3D-matrigel culture, Lapatinib only reduced acini size in the HER2-positive samples via decreased proliferation. Further investigation revealed lapatinib did not reduce self-renewal activity in the CSC population, but their proliferation was decreased regardless of HER2 status. In conclusion we show Lapatinib can reduce DCIS CSC activity, suggesting that the use of Lapatinib in high-risk DCIS patients has the potential to reduce recurrence and the progression of DCIS to invasive disease.

Pathways involved in DCIS stem and progenitor signalling are poorly understood yet are critical to understand DCIS biology and to develop new therapies. Notch and ErbB1/2 receptor signalling cross talk has been demonstrated in invasive breast cancer, but their role in DCIS stem and progenitor cells has not been investigated. We have utilised 2 DCIS cell lines, MCF10DCIS.com (ErbB2-normal) and SUM225 (ErbB2-overexpressing) and 7 human primary DCIS samples were cultured in 3D matrigel and as mammospheres in the presence, absence or combination of the Notch inhibitor, DAPT, and ErbB1/2 inhibitors, lapatinib or gefitinib. Western blotting was applied to assess downstream signalling. In this study we demonstrate that DAPT reduced acini size and mammosphere formation in MCF10DCIS.com whereas there was no effect in SUM225. Lapatinb reduced acini size and mammosphere formation in SUM225, whereas mammosphere formation and Notch1 activity were increased in MCF10DCIS.com. Combined DAPT/lapatinib treatment was more effective at reducing acini size in both DCIS cell lines. Mammosphere formation in cell lines and human primary DCIS was reduced further by DAPT/lapatinib or DAPT/gefitinib regardless of ErbB2 receptor status. Our pre-clinical human models of DCIS demonstrate that Notch and ErbB1/2 both play a role in DCIS acini growth and stem cell activity. We report for the first time that cross talk between the two pathways in DCIS occurs regardless of ErbB2 receptor status and inhibition of Notch and ErbB1/2 was more efficacious than either alone. These data provide further understanding of DCIS biology and suggest treatment strategies combining Notch and ErbB1/2 inhibitors should be investigated regardless of ErbB2 receptor status.

Background: Initial results of the UK/ANZ DCIS (UK, Australia, and New Zealand ductal carcinoma in situ) trial suggested that radiotherapy reduced new breast events of ipsilateral invasive and ductal carcinoma in situ (DCIS) compared with no radiotherapy, but no significant effects were noted with tamoxifen. Here, we report long-term results of this trial., Methods: Women with completely locally excised DCIS were recruited into a randomised 2×2 factorial trial of radiotherapy, tamoxifen, or both. Randomisation was independently done for each of the two treatments (radiotherapy and tamoxifen), stratified by screening assessment centre, and blocked in groups of four. The recommended dose for radiation was 50 Gy in 25 fractions over 5 weeks (2 Gy per day on weekdays), and tamoxifen was prescribed at a dose of 20 mg daily for 5 years. Elective decision to withhold or provide one of the treatments was permitted. The endpoints of primary interest were invasive ipsilateral new breast events for the radiotherapy comparison and any new breast event, including contralateral disease and DCIS, for tamoxifen. Analysis of each of the two treatment comparisons was restricted to patients who were randomly assigned to that treatment. Analyses were by intention to treat. All trial drugs have been completed and this study is in long-term follow-up. This study is registered, number ISRCTN99513870., Findings: Between May, 1990, and August, 1998, 1701 women were randomly assigned to radiotherapy and tamoxifen, radiotherapy alone, tamoxifen alone, or to no adjuvant treatment. Seven patients had protocol violations and thus 1694 patients were available for analysis. After a median follow-up of 12·7 years (IQR 10·9-14·7), 376 (163 invasive [122 ipsilateral vs 39 contralateral], 197 DCIS [174 ipsilateral vs 17 contralateral], and 16 of unknown invasiveness or laterality) breast cancers were diagnosed. Radiotherapy reduced the incidence of all new breast events (hazard ratio [HR] 0·41, 95% CI 0·30-0·56; p<0·0001), reducing the incidence of ipsilateral invasive disease (0·32, 0·19-0·56; p<0·0001) as well as ipsilateral DCIS (0·38, 0·22-0·63; p<0·0001), but having no effect on contralateral breast cancer (0·84, 0·45-1·58; p=0·6). Tamoxifen reduced the incidence of all new breast events (HR 0·71, 95% CI 0·58-0·88; p=0·002), reducing recurrent ipsilateral DCIS (0·70, 0·51-0·86; p=0·03) and contralateral tumours (0·44, 0·25-0·77; p=0·005), but having no effect on ipsilateral invasive disease (0·95, 0·66-1·38; p=0·8). No data on adverse events except cause of death were collected for this trial., Interpretation: This updated analysis confirms the long-term beneficial effect of radiotherapy and reports a benefit for tamoxifen in reducing local and contralateral new breast events for women with DCIS treated by complete local excision., Funding: Cancer Research UK and the Australian National Health and Medical Research Council., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: The epidermal growth factor receptor (EGFR) and Notch signaling pathways have been implicated in self-renewal of normal breast stem cells. We investigated the involvement of these signaling pathways in ductal carcinoma in situ (DCIS) of the breast., Methods: Samples of normal breast tissue (n = 15), pure DCIS tissue of varying grades (n = 35), and DCIS tissue surrounding an invasive cancer (n = 7) were used for nonadherent (i.e., mammosphere) culture. Mammosphere cultures were treated at day 0 with gefitinib (an EGFR inhibitor), DAPT (N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester) (a gamma-secretase inhibitor), or Notch 4-neutralizing antibody. Mammosphere-forming efficiency (MFE) was calculated by dividing the number of mammospheres of 60 microm or more formed by the number of single cells seeded and is expressed as a percentage. The Notch 1 intracellular domain (NICD) was detected immunohistochemically in paraffin-embedded DCIS tissue from 50 patients with at least 60 months of follow-up. All statistical tests were two-sided., Results: DCIS had a greater MFE than normal breast tissue (1.5% versus 0.5%, difference = 1%, 95% confidence interval [CI] = 0.62% to 1.25%, P<.001). High-grade DCIS had a greater MFE than low-grade DCIS (1.6% versus 1.09%, difference = 0.51%, 95% CI = 0.07% to 0.94%, P = .01). The MFE of high-grade DCIS treated with gefitinib in the absence of exogenous EGF was lower than that of high-grade DCIS treated with mammosphere medium lacking gefitinib and exogenous EGF (0.56% versus 1.36%, difference 0.8%, 95% CI = 0.33% to 1.4%, P = .004). Increased Notch signaling as detected by NICD staining was associated with recurrence at 5 years (P = .012). DCIS MFE was reduced when Notch signaling was inhibited using either DAPT (0.89% versus 0.51%, difference = 0.38%, 95% CI = 0.2% to 0.6%, P<.001) or a Notch 4-neutralizing antibody (0.97% versus 0.2%, difference = 0.77%, 95% CI = 0.52% to 1.0%, P<.001)., Conclusion: We describe a novel primary culture technique for DCIS. Inhibition of the EGFR or Notch signaling pathways reduced DCIS MFE.

Introduction: The ras pathway is essential for cell growth and proliferation. The effects of R115777, a farnesyl transferase inhibitor, were investigated in cancer cell lines expressing varying levels of growth factor receptors and with differing ras status. Effects on tumour xenografts and human ductal carcinoma in situ (DCIS) of the breast in a xenograft mouse model were also tested., Method: In vitro, the concentrations required to reduce cell numbers by 50% (50% inhibitory concentration) were established (MDA-MB231, MCF-7, MCF-7/HER2-18, BT-474, SK-BR3 and SKOV3). Human DCIS was implanted in nude mice or, in separate experiments, cultured cells were injected (MDA-MB231, MCF-7/HER2-18, SKOV3) and allowed to form tumours. Proliferation and apoptosis were determined by immunohistochemistry in xenografts and cell tumours., Results: The 50% inhibitory concentrations varied a hundred-fold, from 39 nmol/l (+/- 26 nmol/l) for SKBR3 to 5.9 micromol/l(+/- 0.8 micromol/l) for MDA-MB231. In MCF-7/HER2-18 and SKOV3 cells the levels of tumour growth inhibition were approximately 85% and 40%, respectively. There was a significant decrease in the cell turnover index (CTI; proliferation/apoptosis). In MDA-MB 231 with activated k-ras no inhibition was observed. In treated DCIS xenografts proliferation decreased and apoptosis increased. The CTI ratio between the start and 1 and 2 weeks of treatment were 1.99 and 1.50, respectively, for controls and 0.85 (P = 0.005) and 0.75 (P = 0.08) for treated xenografts., Conclusion: Treatment with the farnesyl transferase inhibitor reduced cell growth in vitro and cell tumour growth in vivo. In DCIS treatment resulted in a reduced CTI. R115777 is a promising treatment for breast cancer but the relation between effect and growth factor receptor and ras status has to be established.

The type 1 tyrosine kinase receptor HER2 (c-erbB2/neu) is associated with resistance to hormone therapy and poor survival in invasive breast cancer, whereas HER4 expression is associated with endocrine responsiveness. Patterns of tyrosine kinase receptor coexpression may aid prediction of recurrence risk after surgery for ductal carcinoma in situ (DCIS). Women who had undergone surgery for pure DCIS were studied. Out of 129 primary tumors, 39 had recurred and 90 had not recurred after 5 years of follow-up. Primary tumors were compared for HER2, HER3, and HER4, estrogen receptor, and Ki67 by immunohistochemistry. HER2 was expressed in 58%, HER3 in 49%, and HER4 in 63% of nonrecurrent DCIS, compared with HER2 expression in 82% (P = 0.008), HER3 expression in 71% (P = 0.04), and HER4 expression in 36% (P = 0.004) in DCIS that subsequently recurred. Dually expressing HER2/4 DCIS was more likely to be estrogen receptor positive than HER2-only-expressing DCIS (73% versus 53%; P = 0.05). HER2 expression was associated with a higher percentage and HER4 expression a significantly lower percentage of proliferating DCIS cells (median, 13.8% versus 8.4%; P = 0.001). Coexpression of HER2 with HER4 was associated with reduced recurrence compared with HER2-only positive DCIS (P = 0.003). This association remained significant when analyzing only high nuclear-grade DCIS (P = 0.015). Low nuclear grade, low proliferation rate and presence of HER4 expression were independent predictors of nonrecurrence. Potentially, HER4 expression may identify women who could avoid radiotherapy after breast-conserving surgery for DCIS.