Performance of HER2 DAKO HercepTest and Ventana 4B5 immunohistochemical assays on detecting HER2 gene-amplification in uterine serous carcinomas.

We compared the performance of two commonly-used HER2 immunohistochemistry (IHC) assays in uterine serous carcinomas (USC), correlating with HER2 gene amplification by fluorescence in-situ hybridization (FISH). Sixty-five USCs were stained by both HercepTest™ and PATHWAY 4B5 assays. FISH was performed by HER2 IQFISH pharmDx. Consensus HER2 IHC scoring was performed, and HER2 testing results were evaluated using USC-specific criteria. Complete concordance between HercepTest and 4B5 assays was achieved in 44/65 tumors (68%). The overall HER2 IHC/FISH concordance was 94% (45/48) by HercepTest and 91% (42/46) by 4B5. All HER2 IHC 3+ cases with HercepTest (n = 6) and 4B5 (n = 4) were gene-amplified, corresponding to specificities of 100%. For cases with IHC 2+, 41% (7/17) by HercepTest and 42% (8/19) by 4B5 had HER2 gene amplification. The sensitivity for HercepTest and 4B5 were 38% and 25%, respectively, at a cut-off of IHC 3+ (P = 0.50), and were 81% and 75%, respectively, at a cut-off of IHC 2+ (P > 0.99). Among HER2 IHC 0-1+ cases, 3/42 cases by HercepTest and 4/42 cases by 4B5 showed amplified FISH results, corresponding to overall false negative rates of 19% for HercepTest and 25% for 4B5. By using USC-specific IHC scoring criteria, both HercepTest and 4B5 assays showed high specificities (100%) for HER2 gene amplification in IHC 3+ cases, high IHC/FISH concordance, and comparable sensitivity for detecting HER2 gene amplification. The notable false negative rates using IHC 2+ as a cut-off for reflexing FISH analysis may warrant consideration for performing FISH in IHC 1+ cases until more data become available.

Interobserver and Interantibody Reproducibility of HER2 Immunohistochemical Scoring in an Enriched HER2-Low-Expressing Breast Cancer Cohort.

OBJECTIVES: We assessed the interobserver and interantibody reproducibility of HER2 immunohistochemical scoring in an enriched HER2-low-expressing breast cancer cohort. METHODS: A total of 114 breast cancer specimens were stained by HercepTest (Agilent Dako) and PATHWAY anti-HER2 (4B5) (Ventana) antibody assays and scored by 6 breast pathologists independently using current HER2 guidelines. Level of agreement was evaluated by Cohen κ analysis. RESULTS: Although the interobserver agreement rate for both antibodies achieved substantial agreement, the average rate of agreement for HercepTest was significantly higher than that for the 4B5 clone (74.3% vs 65.1%; P = .002). The overall interantibody agreement rate between the 2 antibodies was 57.8%. Complete interobserver concordance was achieved in 44.7% of cases by HercepTest and 45.6% of cases by 4B5. Absolute agreement rates increased from HER2 0-1+ cases (78.1% by HercepTest and 72.2% by 4B5; moderate agreement) to 2-3+ cases (91.9% by HercepTest and 86.3% by 4B5; almost perfect agreement). CONCLUSIONS: Our results demonstrated notable interobserver and interantibody variation on evaluating HER2 immunohistochemistry, especially in cases with scores of 0-1+, although the performance was much more improved among breast-specialized pathologists with the awareness of HER2-low concept. More accurate and reproducible methods are needed for selecting patients who may benefit from the newly approved HER2-targeting agent on HER2-low breast cancers.

The Rochester Modified Magee Algorithm (RoMMa): An Outcomes Based Strategy for Clinical Risk-Assessment and Risk-Stratification in ER Positive, HER2 Negative Breast Cancer Patients Being Considered for Oncotype DX® Testing.

INTRODUCTION: Multigene genomic profiling has become the standard of care in the clinical risk-assessment and risk-stratification of ER+, HER2- breast cancer (BC) patients, with Oncotype DX® (ODX) emerging as the genomic profile test with the most support from the international community. The current state of the health care economy demands that cost-efficiency and access to testing must be considered when evaluating the clinical utility of multigene profile tests such as ODX. Several studies have suggested that certain lower risk patients can be identified more cost-efficiently than simply reflexing all ER+, HER2- BC patients to ODX testing. The Magee equationsTM use standard histopathologic data in a set of multivariable models to estimate the ODX recurrence score. Our group published the first outcome data in 2019 on the Magee equationsTM, using a modification of the Magee equationsTM combined with an algorithmic approach-the Rochester Modified Magee algorithm (RoMMa). There has since been limited published outcome data on the Magee equationsTM. We present additional outcome data, with considerations of the TAILORx risk-stratification recommendations. METHODS: 355 patients with an ODX recurrence score, and at least five years of follow-up or a BC recurrence were included in the study. All patients received either Tamoxifen or an aromatase inhibitor. None of the patients received adjuvant systemic chemotherapy. RESULTS: There was no significant difference in the risk of recurrence in similar risk categories (very low risk, low risk, and high risk) between the average Modified Magee score and ODX recurrence score with the chi-square test of independence (p > 0.05) or log-rank test (p > 0.05). Using the RoMMa, we estimate that at least 17% of individuals can safely avoid ODX testing. CONCLUSION: Our study further reinforces that BC patients can be confidently stratified into lower and higher-risk recurrence groups using the Magee equationsTM. The RoMMa can be helpful in the initial clinical risk-assessment and risk-stratification of BC patients, providing increased opportunities for cost savings in the health care system, and for clinical risk-assessment and risk-stratification in less-developed geographies where multigene testing might not be available.

HER2-low breast cancers: Current insights and future directions.

In light of the significant clinical benefits of novel HER2-targeting antibody-drug conjugates in advanced HER2-low expressing breast cancers in recent phases I and III clinical trials, particularly trastuzumab-deruxtecan (T-Dxd), the new "HER2-low" category in breast cancers (breast cancer with a HER2 IHC score of 1+, or 2+ without gene amplification) has gained increasing attention. In the past year, "HER2-low" breast cancers have been under active investigation by both oncologists and pathologists. In this current review, we update the recent cutting-edge research on HER2-low breast cancers, with a focus on the biology of HER2-low breast cancers, the issues on the identification of HER2-low breast cancers by immunohistochemistry in current practice of pathology, and the future directions in this emerging category in breast cancers.

Significance of HER2 in Microinvasive Breast Carcinoma.

OBJECTIVES: We compared the clinicopathologic features, clinical management, and outcomes of human epidermal growth factor receptor 2 (HER2)-expressing and nonexpressing microinvasive breast carcinomas (MiBC) to explore the significance of HER2 in MiBC. METHODS: Clinicopathologic and follow-up information of cases with final diagnosis of MiBC with known HER2 status between 2007 and 2019 were analyzed. RESULTS: Nineteen (41.3%) HER2-positive (HER2+) and 27 (58.7%) HER2-negative (HER2-) MiBCs were identified. HER2 positivity was likely to be associated with high nuclear grade, presence of tumor-infiltrating lymphocytes, hormonal receptor negativity, and increased Ki-67 in both microinvasive and associated in situ carcinomas. Nodal metastases were found in 2 ER+/HER2- cases (5.3%). One HER2+ case was found to have isolated tumor cells in the axillary node. The majority of patients with HER2+ MiBCs (76.5%) did not receive HER2-targeted therapy. All patients with available follow-up were alive without recurrence or distant metastasis, with a median follow-up of 38 months. CONCLUSIONS: Similar to the larger size of invasive breast carcinomas, HER2 positivity is associated with high-grade morphologic features in MiBCs. However, HER2 overexpression in MiBCs does not appear to be associated with nodal metastasis or worse outcome in our study cohort. The role of HER2-targeted therapy in this clinical setting merits additional study.

Frequency, Clinicopathologic Characteristics, and Follow-up of HER2-Positive Nonpleomorphic Invasive Lobular Carcinoma of the Breast.

OBJECTIVES: To investigate human epidermal growth factor receptor 2 (HER2)-positive nonpleomorphic invasive lobular carcinoma (ILC), which has rarely been addressed. METHODS: Clinicopathologic characteristics and follow-up of HER2-positive nonpleomorphic ILCs were collected and compared to those of HER2-negative counterparts. RESULTS: Twenty-one cases of HER2-positive nonpleomorphic ILCs were identified, 6.3% of the study population. Compared to HER2-negative nonpleomorphic ILC, patients with HER2 positivity were older (P < .05), likely to be hormonal receptor negative (P < .01), and had higher histologic grade and angiolymphatic invasion (P < .01). HER2 positivity in nonpleomorphic ILCs was associated with higher recurrence/metastasis with hazard ratio of 2.03 (P < .05). No patient who received neoadjuvant therapy achieved pathologic complete response, and HER2-targeted therapy tended to reduce recurrence/metastasis in patients with HER2-positive nonpleomorphic ILC. CONCLUSIONS: Our results highlight the existence of HER2 positivity in nonpleomorphic ILCs and reinforce that HER2 is associated with worse prognosis in nonpleomorphic ILC.

Optical segmentation of unprocessed breast tissue for margin assessment.

Visual and tactual examination of unprocessed breast specimens is the standard for intraoperative surgical margin assessment in the United States. However, this procedure does not provide surgeons or pathologists with microscopic views of the tissue, which makes it difficult to accurately assess margin status or the extent of the disease, especially in non-palpable cases. We use a combination of spectral and polarization macroscopic imaging to optically segment the adipose and collagen tissues thus highlighting regions suspected of containing epithelium in order to facilitate optical microscopy techniques. A small study on five lumpectomy and mastectomy samples showed a sensitivity of 70% ± 20% and specificity of 50% ± 10% for adipose segmentation and a sensitivity of 50% ± 20% and specificity of 50% ± 20% for collagen segmentation. This sensitivity and specificity are sufficient for providing morphological information to the pathologist in order to guide microscopic examination of regions likely to be of clinical significance.

Design and validation of two optical beacons for guidewire localization in breast-conserving surgery.

Stereotactically placed guidewires are used for indicating the location of a nonpalpable carcinoma in breast-conserving surgery. Pathologists use the end of the embedded guidewire to guide sectioning during intraoperative margin assessment, but they do not currently have a tool to indicate the location of the guidewire end for informed sectioning. We present analysis and experimental testing of two optical methods for localizing the end of an embedded fiber-optic guidewire: the first uses irradiance emitted from the fiber to indicate the location of the guidewire end, while the second system uses the fiber optic to create a photoacoustic pulse for localization. Both systems locate the end of the guidewire within ±5 mm, which ensures that the lesion of interest is bisected during sectioning. The accuracy of the irradiance-based beacon is influenced by standard margin paints, so the photoacoustic beacon proved more useful under current tissue-handling protocols.

The ubiquitin E3 ligase WWP1 decreases CXCL12-mediated MDA231 breast cancer cell migration and bone metastasis.

Advanced breast cancers preferentially metastasize to bone where cells in the bone microenvironment produce factors that enhance breast cancer cell homing and growth. Expression of the ubiquitin E3 ligase WWP1 is increased in some breast cancers, but its role in bone metastasis has not been investigated. Here, we studied the effects of WWP1 and itch, its closest family member, on breast cancer bone metastasis. First, we immunostained a multi-tumor tissue microarray and a breast cancer tissue microarray and demonstrated that WWP1 and ITCH are expressed in some of breast cancer cases. We then knocked down WWP1 or itch in MDA-MB-231 breast cancer cells using shRNA and inoculated these cells and control cells into the left ventricle of athymic nude mice. Radiographs showed that mice given shWWP1 cells had more osteolytic lesions than mice given control MDA-MB-231 cells. Histologic analysis confirmed osteolysis and showed significantly increased tumor area in bone marrow of the mice. WWP1 knockdown did not affect cell growth, survival or osteoclastogenic potential, but markedly increased cell migration toward a CXCL12 gradient in vitro. Furthermore, WWP1 knockdown significantly reduced CXCL12-induced CXCR4 lysosomal trafficking and degradation. In contrast, itch knockdown had no effect on MDA-MB-231 cell bone metastasis. Taken together, these findings demonstrate that WWP1 negatively regulates cell migration to CXCL12 by limiting CXCR4 degradation to promote breast cancer metastasis to bone and highlight the potential utility of WWP1 as a prognostic indicator for breast cancer bone metastasis.

Giant pancreatic tumor with clinical characteristics of insulinoma but without common pathologic features.

OBJECTIVE: To report a case of a large pancreatic tumor that had clinical characteristics of an insulinoma without classic pathologic features. METHODS: We describe a 58-year-old woman who presented with a 3-month history of symptomatic hypoglycemic episodes, which were characterized by confusion. The laboratory, imaging, and pathologic findings are summarized, the current literature on giant insulinomas is reviewed, and the distinction between clinical and pathologic diagnosis of neuroendocrine tumors is discussed. RESULTS: The biochemical diagnosis of insulinoma was established with concomitant low fasting blood glucose concentrations and inappropriately high insulin levels. An abdominal computed tomographic scan revealed a mass (10 by 11.7 by 9.7 cm) in the head and body of the pancreas, which was resected. Pathologic examination revealed a massive neuroendocrine tumor (13.5 by 11 by 8 cm) without immunohistochemical evidence of insulin expression. Nevertheless, tumor resection resulted in decreased blood insulin levels and resolution of the patient's hypoglycemia. CONCLUSION: Although more than 95% of insulinomas are smaller than 3 cm, this case is unique in that the extremely large pancreatic tumor had clinical characteristics of an insulinoma but did not have the classic pathologic findings. Because of the extensive pancreatic resection, the patient is dependent on both insulin and orally administered pancreatic enzymes but remained free of symptoms and disease recurrence at 1-year follow-up.

Heat shock protein 27 differentiates tolerogenic macrophages that may support human breast cancer progression.

Tumor cells release several factors that can help the progression of the tumor by directly supporting tumor growth and/or suppressing host antitumor immunity. Here, we report that human primary breast tumor cells not only express elevated levels of heat shock protein 27 (Hsp27) at the intracellular level but also release extremely high levels of Hsp27 compared with the same patients' serum Hsp27 levels, predicting an acutely increased concentration of soluble Hsp27 in the human breast tumor microenvironment (HBTM). We demonstrate that Hsp27 levels in the HBTM can be extremely elevated as evidenced by high soluble Hsp27 levels in patients' tumor interstitial fluid. Because increasing numbers of tumor-associated macrophages (TAM) in the HBTM negatively correlate to patients' clinical outcomes and we have previously reported the immunoregulatory activity of soluble Hsp27, here, we tested for any specific effects of soluble Hsp27 on human monocyte to macrophage differentiation. We demonstrate that soluble Hsp27 causes the differentiation of monocytes to macrophages with immuno-tolerizing phenotypes (HLA-DRlow, CD86low, PD-L1high, ILT2high, and ILT4high). We detected the presence of TAMs with similar phenotypes in breast cancer patients. Hsp27-differentiated macrophages induce severe unresponsiveness/anergy in T cells. Moreover, these macrophages lose tumoricidal activity but become extremely proangiogenic, inducing significant neovascularization, a process that is critically important for tumor growth. Thus, our data demonstrate a novel immune escape and tumor growth-supporting mechanism mediated by soluble Hsp27 that may be operative in human breast cancer.

Comparative effectiveness of ductal carcinoma in situ management and the roles of margins and surgeons.

BACKGROUND: The high incidence of ductal carcinoma in situ (DCIS) and variations in its treatment motivate inquiry into the comparative effectiveness of treatment options. Few such comparative effectiveness studies of DCIS, however, have been performed with detailed information on clinical and treatment attributes. METHODS: We collected detailed clinical, nonclinical, pathological, treatment, and long-term outcomes data from multiple medical records of 994 women who were diagnosed with DCIS from 1985 through 2000 in Monroe County (New York) and the Henry Ford Health System (Detroit, MI). We used ipsilateral disease-free survival models to characterize the role of treatments (surgery and radiation therapy) and margin status (positive, close [<2 mm], or negative [≥2 mm]) and logistic regression models to characterize the determinants of treatments and margin status, including the role of surgeons. All statistical tests were two-sided. RESULTS: Treatments and margin status were statistically significant and strong predictors of long-term disease-free survival, but results varied substantially by surgeon. This variation by surgeon accounted for 15%-35% of subsequent ipsilateral 5-year recurrence rates and for 13%-30% of 10-year recurrence rates. The overall differences in predicted 5-year disease-free survival rates for mastectomy (0.993), breast-conserving surgery with radiation therapy (0.945), and breast-conserving surgery without radiation therapy (0.824) were statistically significant (P(diff) < .001 for each of the differences). Similarly, each of the differences at 10 years was statistically significant (P < .001). CONCLUSIONS: Our work demonstrates the contributions of treatments and margin status to long-term ipsilateral disease-free survival and the link between surgeons and these key measures of care. Although variation by surgeon could be generated by patients' preferences, the extent of variation and its contribution to long-term health outcomes are troubling. Further work is required to determine why women with positive margins receive no additional treatment and why margin status and receipt of radiation therapy vary by surgeon.

A lower Allred score for progesterone receptor is strongly associated with a higher recurrence score of 21-gene assay in breast cancer.

Among the 77 infiltrating breast carcinomas, we found that progesterone receptor (PR) expression was inversely associated with recurrence score (RS, p < .0001). RS is also significantly associated with tubule formation, mitosis, and luminal B subtype. The equation of RS = 17.489 + 2.071 (tubal formation) + 2.926 (mitosis) -2.408 (PR) -1.061 (HER2) + 7.051 (luminal A) + 29.172 (luminal B) predicts RS with an R² of 0.65. In conclusion, PR negativity, luminal B subtype, tubal formation, and mitosis are strongly correlated with a higher RS.

Confocal microscopy of unfixed breast needle core biopsies: a comparison to fixed and stained sections.

BACKGROUND: Needle core biopsy, often in conjunction with ultrasonic or stereotactic guided techniques, is frequently used to diagnose breast carcinoma in women. Confocal scanning laser microscopy (CSLM) is a technology that provides real-time digital images of tissues with cellular resolution. This paper reports the progress in developing techniques to rapidly screen needle core breast biopsy and surgical specimens at the point of care. CSLM requires minimal tissue processing and has the potential to reduce the time from excision to diagnosis. Following imaging, specimens can still be submitted for standard histopathological preparation. METHODS: Needle core breast specimens from 49 patients were imaged at the time of biopsy. These lesions had been characterized under the Breast Imaging Reporting And Data System (BI-RADS) as category 3, 4 or 5. The core biopsies were imaged with the CSLM before fixation. Samples were treated with 5% citric acid and glycerin USP to enhance nuclear visibility in the reflectance confocal images. Immediately following imaging, the specimens were fixed in buffered formalin and submitted for histological processing and pathological diagnosis. CSLM images were then compared to the standard histology. RESULTS: The pathologic diagnoses by standard histology were 7 invasive ductal carcinomas, 2 invasive lobular carcinomas, 3 ductal carcinomas in-situ (CIS), 21 fibrocystic changes/proliferative conditions, 9 fibroadenomas, and 5 other/benign; two were excluded due to imaging difficulties. Morphologic and cellular features of benign and cancerous lesions were identified in the confocal images and were comparable to standard histologic sections of the same tissue. CONCLUSION: CSLM is a technique with the potential to screen needle core biopsy specimens in real-time. The confocal images contained sufficient information to identify stromal reactions such as fibrosis and cellular proliferations such as intra-ductal and infiltrating carcinoma, and were comparable to standard histologic sections of the same tissue. Morphologic and cellular features of benign and cancerous lesions were identified in the confocal images. Additional studies are needed to 1.) establish correlation of the confocal and traditional histologic images for the various diseases of the breast; 2.) validate diagnostic use of CSLM and; 3.) further define features of borderline lesions such as well-differentiated ductal CIS vs. atypical hyperplasia.

Metastatic versus primary oncocytic papillary adenocarcinoma of the endometrium: a report of a case and review of the literature.

We report a case of an oncocytic papillary adenocarcinoma of the endometrium in an 89-year-old female with vaginal bleeding. Imaging studies revealed lesions in the uterus, kidneys, pancreas, gluteus, and an enlarged portacaval lymph node. Diagnostic workup included an endometrial biopsy which showed malignant, oncocytic cells in a predominantly papillary pattern. These cells stained positive for epithelial markers (pan-cytokeratin, CK7, epithelial membrane antigen) and weakly for estrogen receptor. The cells were negative for cytokeratin 903, CAM 5.2, progesterone receptor, CD10, RCC Marker, CA-125, c-kit, and vimentin. Consultation with experts in Gynecologic and Genitourinary pathology returned a diagnosis of "adenocarcinoma compatible with metastatic renal cell carcinoma"--an intriguing possibility worthy of further exploration. To our knowledge, there are no reports in the literature of metastatic oncocytic papillary renal cell carcinoma to the endometrium. The clinical and pathologic features of oncocytic papillary endometrial lesions, including primary and metastatic processes, are reviewed.

The pen and the scalpel: effect of diffusion of information on nonclinical variations in surgical treatment.

BACKGROUND: As information is disseminated about best practices, variations in patterns of care should diminish over time. OBJECTIVE: To test the hypotheses that differences in rates of a surgical procedure are associated with type of insurance in an era of evolving practice guidelines and that insurance and site differences diminish with time as consensus guidelines disseminate among the medical community. METHODS: We use lymph node dissection among women with ductal carcinoma in situ (DCIS) as an example of a procedure with uncertain benefit. Using a sample of 1051 women diagnosed from 1985 through 2000 at 2 geographic sites, we collected detailed demographic, clinical, pathologic, and treatment information through abstraction of multiple medical records. We specified multivariate logistic models with flexible functions of time and time interactions with insurance and treatment site to test hypotheses. RESULTS: Lymph node dissection rates varied significantly according to site of treatment and insurance status after controlling for clinical, pathologic, treatment, and demographic characteristics. Rates of lymph node dissection decreased over time, and differences in lymph node dissection rates according to site and generosity of insurance were no longer significant by the end of the study period. CONCLUSIONS: We have demonstrated that rates of a discretionary surgical procedure differ according to nonclinical factors, such as treatment site and type of insurance, and that such unwarranted variation decreases over time with diminishing uncertainty and in an era of diffusion of clinical guidelines.

C35 (C17orf37) is a novel tumor biomarker abundantly expressed in breast cancer.

Identification of shared tumor-specific targets is useful in developing broadly applicable therapies. In a study designed to identify genes up-regulated in breast cancer, a cDNA clone corresponding to a novel gene C35 (C17orf37) was selected by representational difference analysis of tumor and normal human mammary cell lines. Abundant expression of C35 transcript in tumors was confirmed by Northern blot and real-time PCR. The C35 gene is located on chromosome 17q12, 505 nucleotides from the 3' end of the ERBB2 oncogene, the antigenic target for trastuzumab (Herceptin) therapy. The chromosomal arrangement of the genes encoding C35 and ERBB2 is tail to tail. An open reading frame encodes a 12-kDa protein of unknown function. Immunohistochemical analysis detected robust and frequent expression of C35 protein, including 32% of grade 1 and 66% of grades 2 and 3 infiltrating ductal carcinomas of the breast (in contrast to 20% overexpressing HER-2/neu), 38% of infiltrating lobular carcinoma (typically HER-2/neu negative), as well as tumors arising in other tissues. C35 was not detected in 38 different normal human tissues, except Leydig cells in the testes and trace levels in a small percentage of normal breast tissue samples. The distinct and favorable expression profile of C35 spanning early through late stages of disease, including high frequency of overexpression in various breast carcinoma, abundant expression in distant metastases, and either absence or low level expression in normal human tissues, warrants further investigation of the relevance of C35 as a biomarker and/or a target for development of broadly applicable cancer-specific therapies.

Expression patterns of ER-alpha, PR, HER-2/neu, and EGFR in different cell origin subtypes of high grade and non-high grade ductal carcinoma in situ.

We have previously reported that high grade and non-high grade ductal carcinoma in situ (DCIS) of the breast can be subdivided into 3 cell origin subtypes (luminal, basal/stem, and null), and that high grade DCIS is more frequently associated with basal/stem cell subtypes compared to non-high grade DCIS. Here we refine the relationships between these 3 subtypes and the expression patterns of estrogen receptor-alpha (ER-alpha), progesterone receptor (PR), HER-2/neu, and epidermal growth factor receptor (ERFR) in 53 cases of non-high grade and 46 cases of high nuclear grade DCIS. Using a panel of antibodies to ER-alpha, PR, HER-2/neu, and EGFR, along with cytokeratin (CK) markers (CK5/6, CK8, CK14, CK17, and CK18), we found that all 3 cell origin subtypes can express ER-alpha and PR, and their expression is higher in non-high grade DCIS than in high grade DCIS; the expression of HER-2/neu is associated with luminal subtype only in non-high grade DCIS, but can be seen in all 3 subtypes in high grade DCIS; the expression of EGFR is low and is present only in luminal cell subtypes in both high and non-high grade DCIS. Basal/ stem cell and null cell subtypes occur in younger patients in non-high grade DCIS compared to high grade DCIS. In conclusion, the expression patterns of ER-alpha, PR, HER-2/neu, and EGFR are markedly different in different cell origin subtypes of both high grade and non-high grade DCIS, suggesting that cell origin subtypes as well as nuclear grade contribute to the biological and molecular heterogeneity of DCIS.

Relationship between nuclear grade of ductal carcinoma in situ and cell origin markers.

Ductal carcinoma in situ (DCIS) is a group of heterogeneous lesions genetically, morphologically, and biologically. Recently, breast epithelium in the terminal ductal lobular unit has been sub-classified based on the expression of several cytokeratin markers as stem cells (CK5/6 +), luminal cells (CK8, CK18 +), and basal cells (CK14, CK17 +). In this study we describe the relationship between DCIS of different nuclear grades (non-high grade and high grade) and these cell origin markers. Fifty-three cases of non-high grade and 46 cases of high grade DCIS were selected, and representative sections from each case were stained with antibodies to these cytokeratin markers. High grade DCIS showed significantly higher rates of expression with stem and basal cell markers compared with non-high grade DCIS (p <0.05). The majority of DCIS, both high grade and non-high grade, expressed luminal cell markers (67% to 91%) and single type of cell origin marker (72% to 87%). High-grade DCIS more frequently co-expressed all three types of cell origin markers compared with non-high grade DCIS (p <0.05). In summary, a subset of high grade DCIS frequently rises from stem or/and basal cell populations; the subset is associated with poor prognosis in invasive breast carcinoma. Thus, these markers may be used to identify a potentially more aggressive subgroup of breast carcinoma at its pre-invasive stage (DCIS), and to manage it accordingly. Second, most DCIS express luminal cell markers, suggesting that malignant transformation occurs relatively late along the cell differentiation pathway, contrary to the traditional belief that most neoplasms arise from a more primitive stem cell population. Third, the majority of DCIS exclusively express one type of progenitor marker, indicating that in most incidences they may arise from a single progenitor population. Last, triple expression of all types of cell origin marker is frequently associated with high grade DCIS, suggesting that more complicated pathways are involved in these more aggressive lesions. Further studies are needed to delineate the relationships of cell origin markers in DCIS and invasive carcinoma to the clinical outcome.