Primary Invasive Breast Carcinomas Research Articles

Abstract PO5-24-07: HER2 EXPRESSION HETEROGENEITY PATTERN IN INVASIVE BREAST CARCINOMAS: FREQUENCY, DISTRIBUTION AND RELATION TO MORPHOLOGICAL VARIABLES

Abstract Human epidermal growth factor receptor 2 (HER2), a critical contributor to breast cancer development, is found to be amplified and overexpressed in approximately 15-20% of cases, making it a significant factor in carcinogenesis. This scenario was targeted by anti-HER2 drugs approved by several regulatory agencies in the past 15 years. Recently, novel anti-HER2 antibody-drug conjugates (ADCs) were approved to metastatic breast cancer with some HER2 expression albeit not due to amplification of the gene. Despite being classified as HER2 negative, most of these tumors exhibit detectable amounts of HER2 protein, reinforcing the challenging task of HER2 expression evaluation. In this scenario, it is very important to evaluate the spectrum of HER2 expression within a tumor due to its heterogeneity. We designed a retrospective linear study to reanalyze all HER2 immunohistochemical core biopsy slides of patients with primary invasive breast carcinomas (IBC) diagnosed and treated at São Paulo Federal University Hospital between 2019 and 2023. Pathological variables (histological subtype, histological grading, and hormonal receptors expression) were collected in pathology reports. Only patients with available slides and blocks were enrolled. HER2 slides were evaluated by three observers in consensus to access ASCO-CAP 2018 guidelines HER2 expression; presence or absence of HER2 expression heterogeneity; pattern of heterogeneity; frequency of the primary and secondary HER2 score in heterogeneous cases; and frequency of HER2 score in cases with homogeneous expression. Statistical analyses were performed with Chi-Square and Mann–Whitney U test using SSPS (26.0) program. 353 cases were included in this study. 104 (29,5%) were under 50 years and 249 (70,5%) over 50 years. 54,1% cases were left sided and 45,9% right sided. IBC of no special type comprehended 324 cases (91,8%) and invasive lobular carcinomas (ILC) were represented by 26 cases (7,4%); less than 1% of the cases were rare subtypes. Overall, HER2 results was negative in 296 (83,9%) cases and positive in 42 (11,9%) cases; HER2 2+ accounted by 15 cases (4,2%). Out of the negative cases, 235 (79.4%) were classified as 0+ and 61 (20.6%) were classified as 1+. Homogenous HER2 expression was observed in 287 cases (81,3%) with predominance of 0+ expression (80,8% - 232 cases), followed by 1+ (9,4% - 27 cases). ITH was present in 66 cases (18,7%), in which the subtyping was represented by 39 scattered (59,1%), 25 clustered (37,9%) and 2 mosaic (3%). The most prevalent score in this group was 1+ (51,5% - 34 cases), followed by 3+ (25,8% - 17 cases); the secondary score was predominantly categorized as 0+ (58,3%), followed by 1+ (20%) and 2+ (20%); only one case showed as 3+ expression. In the ILC group, 24 cases (92,3%) exhibited homogeneous HER2 expression, with predominant 0+ score (75% - 18 cases), while 2 cases (7,7%) showed heterogeneous expression. Out of the cases with heterogeneous HER2 expression, one exhibited a clustered heterogeneity pattern, with a primary HER2 score of 1+ and a secondary score of 0+. The other case displayed a scattered heterogeneity pattern, with a primary HER2 score of 3+ and a secondary score of 2+. There was a statistically significant association between HER2 expression heterogeneity and histologic grade (p = 0.005), and a marginal association with estrogen (p = 0.060) and progesterone (p = 0.060) expression. Tumor size wasn’t associated with heterogeneity (p = 0,071). We conclude that heterogeneity is prevalent in HER2 expression, especially in IBC, and should be addressed in pathology reports, especially in the ADCs scenario. Citation Format: Angela Flavia Waitzberg, Lucas de Figueiredo Barbosa, Adilson Monteiro dos Santos Filho, Ana Luiza da Cruz, Lisandra Gonzalez Porta Nova, Karla Calaça Kabbach Prigenzi. HER2 EXPRESSION HETEROGENEITY PATTERN IN INVASIVE BREAST CARCINOMAS: FREQUENCY, DISTRIBUTION AND RELATION TO MORPHOLOGICAL VARIABLES [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-24-07.

Abstract PO4-15-11: HER2 STATUS AND TUMOR HETEROGENEITY IN INVASIVE BREAST CARCINOMAS: CLINICAL PATHOLOGICAL IMPACT

Abstract Human epidermal growth factor receptor 2 (HER2) is a major player in breast carcinogenesis with a range of 15-20% of cases harboring gene amplification and overexpression turning the tumor eligible to over eight anti-HER2 drugs in the past 15 years. Recently, novel anti-HER2 antibody-drug conjugates (ADCs) treatment was recently approved to metastatic breast cancer bearing some HER2 expression albeit not due to gene amplification. Immunohistochemically classified, by ASCO-CAP Guidelines (2018), as 1+ cases were enrolled in clinical trials and benefited by the addition of ADCs to chemotherapy. Despite being classified as HER2 negative, most tumors exhibit detectable levels of HER2 protein, reinforcing the importance of HER2 expression evaluation. HER-2 intratumoral heterogeneity (ITH) is reported in up to 40% of breast cancers and is defined as the coexistence of subpopulations of tumor cells with different HER2 gene or protein expression. In this scenario, it becomes very important to evaluate the spectrum of HER-2 expression in correlation with pathological factors as ITH is associated with poor prognosis and anti-HER2 resistance. We designed a retrospective linear study to reanalyze all HER2 immunohistochemical core biopsy slides of patients with primary invasive breast carcinomas (IBC) diagnosed and treated at São Paulo Federal University Hospital between 2019 and 2023. Clinical variables (age, laterality, tumor size by ultrasound imaging, BI-RADS) were collected from clinical files. HER2 slides were reviewed by three observers and reported regarding status by ASCO-CAP 2018 guidelines, HER2 heterogeneity and patterns. Statistical analyses were performed with Chi-Square test of independence, Fisher's exact test and Mann–Whitney U test using IBM® SPSS® Statistics (26.0) software. 353 cases were included; the mean age of the patients at the time of diagnosis was 58 years old. 191 cases (54,1%) were left sided and 162 cases (45,9%) were right sided. Regarding BI-RADS report, the major category was 4 (140 cases), followed by 5 (119 cases). Out of the 164 patients who underwent clinical follow-up at our institute, 14 deaths were reported. Concerning pathological features, IBC of no special type was the prevalent histological subtype with 304 cases (86,1%), followed by invasive lobular carcinoma, with 26 cases (7,4%). 296 cases (83,9%) were HER2 negative and 42 (11,9%) were HER2 positive; 15 cases were HER2 2+ (4,2%). Amongst negative cases, 235 were HER2 0+ and 61 were HER2 1+. Considering ITH, 287 cases (81,3%) were HER2 homogenous with 0+ score as the most prevalent, presenting with 232 cases (80%). 66 cases (18,7%) had ITH, with 1+ as the most prevalent primary score, with 34 cases (51,5%), followed by 3+, with 17 cases (25,8%). Not only HER2 positive carcinomas, but also the presence of heterogeneity in HER2 expression was associated with death outcome (p=0,003 and p=0,001, respectively). Also, HER2 positive IBC had larger tumor size compared to HER2 negative carcinomas (mean size of 25,6 mm x 31,3 mm, respectively; p=0,012); HER2 heterogeneity showed no statistical significance when associated with tumor size (p=0,165). We conclude that ITH is prevalent in HER2 expression and should be addressed in pathology reports since it may play an additional role in tumor progression and drug response, especially in the ADCs scenario. Citation Format: Karla Calaça Kabbach Prigenzi, Lisandra Gonzalez Porta Nova, Adilson Monteiro dos Santos Filho, Ana Luiza da Cruz, Lucas de Figueiredo Barbosa, Angela Flavia Waitzberg. HER2 STATUS AND TUMOR HETEROGENEITY IN INVASIVE BREAST CARCINOMAS: CLINICAL PATHOLOGICAL IMPACT [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-15-11.

Abstract PO3-03-04: Metaplastic breast cancer: a single center retrospective study

Abstract Background: Metaplastic breast cancer (MBC) is a rare malignancy that accounts for up to 1% of all primary invasive breast carcinomas (BC). It is histologically heterogeneous, usually presents with a triple-negative phenotype and comprises low-grade and high-grade (HG) variants. HG variants have a higher risk of recurrence and a shorter disease-free and overall survival compared to other BC subtypes. Our research aimed to estimate the prevalence of HG-MBC among the Slovenian population and determine the characteristics of patients (pts) and tumours and the disease outcome. Patients and methods: Our retrospective study included pts diagnosed with HG-MBC at the Institute of Oncology Ljubljana from January 1983 until January 2021. Clinicopathologic characteristics such as tumour subtype, size and grade, nodal status, hormonal receptors (HR) and HER-2 status, lymphovascular invasion (LVI), tumour-infiltrating lymphocytes (TIL) and presence of germline BRCA mutation status were determined. The survival analyses were performed using the Kaplan-Meier method. The Cox proportional hazard model examined the association between risk factors and survival outcomes. Results: We evaluated 113 HG-MBC pts among a total of 27700 pts diagnosed with BC over 38 years (0.41%). The median age was 61.6 years (range 29.7 -93.9), majority of pts were postmenopausal (78.69%). The median follow-up was 15.5 years. The most common tumour subtype in our cohort was mixed MBC (53 cases, 46.9%), followed by MBC with mesenchymal differentiation (24 cases, 21.2%), squamous cell carcinoma (20 cases, 17.7%) and spindle cell carcinoma (16 cases, 14.2%). From the 113 evaluated pts, we obtained data about the stage in 105 pts, pathological tumour size in 100 pts, number of positive lymph nodes in 99 pts, HR status in 95 pts, HER2 status in 76 pts, grade in 97 pts, LVI in 85 pts, MIB-1 in 41 pts and TIL in 77 pts. At diagnosis, 17/105 pts (16.2%) had stage I disease, 59/105 pts (56.2%) stage II, 25/105 pts (23.8%) stage III and 4/105 pts (3,8%) stage IV. Most tumours were poorly differentiated (90/97, 92.2%) without LVI (60/85, 70.6%). Only 6/95 (6,3%) pts had positive HR, 7/76 (9.2%) pts had positive HER-2 status and 8/77(10.4%) pts intensive TIL. Overall, 13 pts were tested for BRCA germline mutation, among which only 1 (7,7%) had BRCA1 mutation. Modified radical mastectomy was the most frequent type of surgery (63.5%); 49.5% of the patients received radiotherapy. In total, 66/113 pts received CT: from 1983 to 2000, 16/36 (44.4%), and after 2000 50/77 (74.9%). In the first period, most pts received CMF (14/16; 87.5%) and anthracyclines and taxanes (27/50; 54%) in the second period. The disease progressed at 37 pts. At 19 pts, new malignancies were found. 55 pts died, 37 of them because of BC. Five- and 10-year disease-free survival (DFS) was 61.7% and 54.1%, while 5-and 10-year overall survival (OS) was 67.1 % and 56.7%, respectively. However, DFS and OS did not differ between the pre-2000 and post-2000 periods. The best outcome was found in pts with squamous cell carcinoma (5- and 10-year DFS 83.5% and 77.0% and 5-and 10- year OS 89.4 % and 83.0%). A subtype of MBC (squamous cell vs other) was the only predictive factor in multivariate analysis for both DFS (HR 0.21; 95% CI 0.05-0.92; p = 0.038 and OS (HR 0.27; 95%CI 0.09-0.78; p = 0.016), no association was seen between survival and tumour size, nodal status, stage, HR and HER2 status, grade, LVI and TILs. Visceral organs were the most common localization of distant metastases (21/37, 56.8%). Metastases in CNS occurred in 9/37 (24.3%) pts. Median OS after the first progression was only 0.9 years. Conclusions: The proportion of HG-MBC in our cohort of pts is 0.41%. Disease outcomes are poor; the 10-year OS of pts with early HG-MBC is only 56.6% and has not improved during the last decades. Squamous cell differentiation predicts a better outcome and is the only independent predictive factor of DFS and OS among HG-MBC pts. Citation Format: Maša Auprih, Gorana Gasljevic, Eva Setina, Anja Zizek, Simona Borstnar. Metaplastic breast cancer: a single center retrospective study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-03-04.

Socioeconomic Deprivation and Invasive Breast Cancer Incidence by Stage at Diagnosis: A Possible Explanation to the Breast Cancer Social Paradox.

In this study, we assessed the influence of area-based socioeconomic deprivation on the incidence of invasive breast cancer (BC) in France, according to stage at diagnosis. All women from six mainland French departments, aged 15+ years, and diagnosed with a primary invasive breast carcinoma between 2008 and 2015 were included (n = 33,298). Area-based socioeconomic deprivation was determined using the French version of the European Deprivation Index. Age-standardized incidence rates (ASIR) by socioeconomic deprivation and stage at diagnosis were compared estimating incidence rate ratios (IRRs) adjusted for age at diagnosis and rurality of residence. Compared to the most affluent areas, significantly lower IRRs were found in the most deprived areas for all-stages (0.85, 95% CI 0.81-0.89), stage I (0.77, 95% CI 0.72-0.82), and stage II (0.84, 95% CI 0.78-0.90). On the contrary, for stages III-IV, significantly higher IRRs (1.18, 95% CI 1.08-1.29) were found in the most deprived areas. These findings provide a possible explanation to similar or higher mortality rates, despite overall lower incidence rates, observed in women living in more deprived areas when compared to their affluent counterparts. Socioeconomic inequalities in access to healthcare services, including screening, could be plausible explanations for this phenomenon, underlying the need for further research.

Does Nottingham grading of primary invasive breast carcinomas in an Adelaide metropolitan hospital pathology department adhere to the recommended distribution of grading?

Does Nottingham grading of primary invasive breast carcinomas in an Adelaide metropolitan hospital pathology department adhere to the recommended distribution of grading?

266 (PB-082) Poster - Systematic profiling of primary invasive lobular breast carcinoma defines distinct candidates for PD-1/PD-L1 targeting immunotherapy

266 (PB-082) Poster - Systematic profiling of primary invasive lobular breast carcinoma defines distinct candidates for PD-1/PD-L1 targeting immunotherapy

Synchronous double primary small cell lung cancer and invasive ductal breast carcinoma: a case report

BackgroundAlthough lung and breast cancers are common malignancies, the occurrence of primary synchronous neoplasms involving these organs has been rarely reported in literature.Case presentationA 75-year-old female patient presented at a local hospital with a ten-day history of dizziness and slurred speech. A CT contrast-enhanced scan revealed a 4.2 cm mass in the lower lobe of the right lung and a 3.8 cm space-occupying lesion in the right breast. Subsequent breast ultrasound identified a hypoechoic lesion measuring5.41 × 4.75 × 3.06 cm in the right breast, and an ultrasound-guided biopsy confirmed the presence of infiltrating ductal carcinoma of the right breast. The immunohistochemistry analysis of the breast mass revealed positive staining for ER, PR, HER-2, AR and Ki67 in the tumor cells, while negative staining was observed for P63, Calponin, CK5/6 and CK14. MR imaging of the head detected abnormal signals in the right frontal lobe (3.6 cm×2.9 cm in size), left cerebellar hemisphere, and punctate enhancement in the left temporal lobe, indicating potential metastasis. Pathological examination of a lung biopsy specimen confirmed the presence of small cell lung cancer (SCLC). Furthermore, immunohistochemistry analysis of the lung lesions demonstrated positive staining for TTF-1, CK-Pan, Syn, CgA, CD56, P53 (90%) and Ki67 (70%), and negative staining for NapsinA and P40 in the tumor cells. The patient’s diagnosis of SCLC with stage cT2bN0M1c IVB and brain metastases (BM), as well as invasive ductal breast carcinoma (IDC), was confirmed based on the aforementioned results. Whereupon we proposed a treatment plan consisting of whole-brain radiation (40 Gy/20fractions), focal radiotherapy (60 Gy/20fractions), and adjuvant concurrent chemotherapy with oral etoposide (50 mg on days 1 to 20).ConclusionsTo the best of our knowledge, the present case is the first of its kind to describe the synchronous double cancer, consisting of primary SCLC and IDC.

Subtyping of Breast Carcinoma According to ER/PR and HER2/neu Expression: A Cross-Sectional Study from Southern Part of Assam, India

Introduction: Globally, breast carcinoma is the most prevalent and lethal form of cancer in women. Breast cancer is no longer considered a single disease but a complex heterogeneous disease with multiple genetic and epigenetic alterations. The prognosis and management of the disease depend on histological stage, type, grade, tumour size, lymph node status, and the status of hormonal receptors like ER, PR, and Her2/ neu. Recently, more attention has been given to the molecular classification of breast cancer. Aim: To analyse and compare the clinicopathological characteristics of invasive breast cancer in the four breast carcinoma subtypes defined by the immunohistochemical expression of Estrogen Receptor (ER), Progesterone Receptor (PR), and Human Epidermal Growth Factor Receptor 2 (Her2/neu). Materials and Methods: The cross-sectional study was conducted on 64 primary invasive breast carcinoma cases diagnosed on mastectomy specimens between February 1, 2018, and July 30, 2022, in the Department of Pathology at the histopathology section of Silchar Medical College and Hospital, Silchar, Assam, India. Age and tumour characteristics (morphology, grade, stage, and size) and nodal disease status were included in the data for analysis. Immunohistochemical markers were analysed on the sections of these diagnosed cases. IBM Statistical Packages for Social Sciences (SPSS) software was used for data analysis. Qualitative data was presented as frequency and percentage, while quantitative data was presented as mean ±{Standard Deviation (SD)}. The Chi- square test was used to determine the statistical significance of hormonal receptors with the various clinicopathological features. A p-value of <0.05 was considered statistically significant. Results: In present study of 64 cases of invasive breast carcinoma, the mean age of patients was 51.95±12.72 years. Subtyping was performed based on hormonal receptors. Authors found that the Luminal A variety 33 (51.6%) was the most common hormonal subtype in present study, followed by the basal subtype 24 (37.5%). The Luminal A subtype was found to be predominant among others. The majority of the patients (59.4%) had stage-I tumours, and Ductal type carcinoma was the most common (57.8%). Histologically, most of the tumours were poorly differentiated (28, 43.8%), and most were sized ≤2 cm (41, 64.1%). Lymph nodes were not palpable in most of the patients (43, 67.2%). Subtype comparison with respect to age, stage, histological grade, type, size, and nodal status revealed statistically significant outcomes (p-value of <0.05). Conclusion: Classification based on Immunohistochemistry (IHC) provides prognostic and therapeutic information that cannot be obtained from either ER/PR or Her2/Neu status alone. The present study provides the incidence of different molecular subtypes in the southern region of Assam, and comparison among them with statistical correlation offers improved and crucial treatment guidance. IHC classification as a clinical tool for ER/PR and Her2/Neu testing is widely accessible, reasonably priced, based on immunophenotype/biologic phenotype categorisation of breast cancer, and is prognostic as well as partly predictive and needs to be practiced invariably.

Series of rare cases of breast tumour: 8-year review at mankweng Breast Oncology clinic, Limpopo, South Africa

Breast cancer remains the most common cancer in many parts of the world, particularly for women. In March 2015, a Breast Oncology clinic for breast cancer patients was established at Mankweng Hospital. Invasive ductal carcinoma is the most common (87 %) tumour found in Limpopo, and occasionally, another rare tumour of the breast is presented in the Breast Oncology clinic.
 The aim: The main objective is to share the experience of a rare tumour of the breast came across over the past 8 years since the establishment of the Breast Oncology clinic.
 Material and Method: Series of rare case reports of Breast tumours and literature review from the Mankweng Breast Oncology Clinic.
 Result: Rare tumour encountered in Breast Oncology clinic: adenomyoepithelioma, micro-papillary carcinoma of the breast, primary malignant melanoma of the breast, primary non-Hodgkin's lymphoma of the bilateral breast, advanced breast cancer in a case of Down's syndrome, primary neuroendocrine invasive breast carcinoma, sarcoma of the breast.
 Conclusions: Most of these rare cases are presented to the Breast Oncology clinic in the advanced stage. Breast cancer awareness campaign is highly important for women in Limpopo, particularly when attending primary health care for any other conditions.

Comparative expression of trophoblast cell-surface antigen 2 (TROP2) in the different molecular subtypes of invasive breast carcinoma: An immunohistochemical study of 94 therapy-naive primary breast tumors

BackgroundSacituzumab govitecan, targeting trophoblast cell-surface antigen 2 (TROP2), is approved for the treatment of triple-negative and hormone receptor-positive/HER2-negative breast cancers. However, detailed studies comparing TROP2 protein expression in the different molecular subtypes of breast cancer are limited, and definitive evidence supporting the use of TROP2 as a biomarker for predicting response to this agent in patients with breast cancer is currently lacking. ObjectiveTo compare the expression of TROP2 in the different molecular subtypes of breast cancer. MethodsImmunohistochemical staining for TROP2 was performed on 94 therapy-naive primary invasive breast carcinomas, including 25 luminal A-like, 25 luminal B-like, 19 HER2-like, and 25 triple-negative tumors. ResultsIntermediate to high levels of TROP2 expression were observed in the majority of carcinomas of each molecular subtype, with a wide range of expression in each subtype. Occasional tumors with low or absent TROP2 expression were encountered, including two metaplastic carcinomas which were completely negative for TROP2. ConclusionsOur observations support the continued investigation of the efficacy of sacituzumab govitecan in all molecular subtypes of breast carcinoma. Furthermore, the observed wide range of expression of TROP2 suggests that TROP2 may have potential utility as a biomarker for predicting responsiveness to sacituzumab govitecan. If this proves to be the case, then immunohistochemical staining for TROP2 would be critical for identifying those patients whose tumors are completely negative for TROP2, since these patients may be least likely or unlikely to respond to this agent, and alternative therapies may be more appropriate in such instances.

TRPS1, a New Promising Marker for Assessment of Distant Metastatic Breast Cancer.

This article reviewed the identification of breast cancer in the distant metastatic setting through traditional immunohistochemical markers, such as mammaglobin and GATA3, compared with the novel immunohistochemical stain, Trichorhinophalangeal syndrome-1 (TRPS1). We review previous studies evaluating TRPS1 staining, which were conducted using cytology specimens, as well as our recently conducted study evaluating this stain using surgical tissue samples, both from primary and distant metastatic invasive breast carcinoma. In summary, although no immunohistochemical stain is 100% specific or sensitive, in the metastatic setting where tissue available for ancillary studies is limited, TRPS1 was a reliable and even a standalone marker for breast origin, particularly in cases of triple-negative breast cancer.

Trichorhinophalangeal syndrome type 1 (TRPS1) expression in male breast carcinoma

Currently, there is a paucity of highly specific and sensitive markers to identify breast carcinoma in male patients. Immunohistochemical stains commonly used for unmasking primary breast carcinomas include estrogen receptor (ER) and GATA3. However, these markers are commonly expressed in carcinomas originating from other organ systems and can be reduced in breast carcinomas with higher histologic grades. Androgen receptor (AR) may be used to highlight primary male breast cancer, but this marker can also be expressed in other carcinomas. We evaluated TRPS1, a highly sensitive and specific marker for female breast carcinoma, in cases of male breast carcinoma. Through an institutional database search, we identified 72 cases of primary invasive breast carcinoma in male patients. Among ER/progesterone receptor (PR)-positive cancers, 97% showed intermediate or high positivity for both TRPS1 and GATA3. Among HER2-positive cancers, 100% showed intermediate or high positivity for TRPS1 and GATA3. One case of triple-negative breast cancer was collected, showing high positivity for TRPS1 and negativity for GATA3. AR staining was non-specific and heterogeneous: 76% showed high positivity, but the remaining 24% showed low or intermediate positivity. Additionally, among 29 cases of metastatic carcinoma to male breast tissue, 93% were negative for TRPS1, and the remaining 2 cases (7%), which were carcinomas from salivary gland primary tumors, were intermediate positive. TRPS1 is a sensitive and specific marker in the unmasking of male primary invasive breast carcinoma across different subtypes. Additionally, TRPS1 is not expressed in metastatic carcinomas of multiple primaries, with the exception of salivary gland primaries.

Abstract P3-05-18: Unravelling the clinicopathological and functional significance of Replication Protein A (RPA) heterotrimeric complex in sporadic breast cancers

Abstract Unravelling the clinicopathological and functional significance of Replication Protein A (RPA) heterotrimeric complex in sporadic breast cancers Mashael Algethami1, Michael S Toss 1,4, Juliette Brownlie 1, Corinne L Woodcock 1,2, Chandar Jaipal1, Ahmed Shoqafi 1, Katia A Mesquita1, Adel Alblihy1,3, Andrew R Green1, Nigel P Mongan 1,5, Emad A Rakha 1,4, Jennie N Jeyapalan 1,2 and Srinivasan Madhusudan1,6 1 Nottingham Biodiscovery Institute, Academic Unit for Translational Medical Sciences, School of Medicine, University of Nottingham, University Park, Nottingham NG7 2RD, UK. 2 Faculty of Medicine and Health Sciences, Centre for Cancer Sciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire LE12 5RD, UK 3 Medical Center, King Fahad Security College (KFSC), Riyadh 11461, Saudi Arabia. 4 Department of Pathology, Nottingham University Hospital, City Campus, Hucknall Road, Nottingham NG5 1PB, UK. 5 Department of Pharmacology, Weill Cornell Medicine, New York, NY, 10065, USA 6 Department of Oncology, Nottingham University Hospitals, Nottingham NG5 1PB, UK. Introduction: Replication Protein A (RPA) is a critical single-stranded DNA (ssDNA)-binding protein that coats and protects exposed ssDNA from endogenous nucleases. RPA is a heterotrimeric complex consisting of RPA1 (70kDa), RPA2 (32kDa), and RPA3 (14kDa) subunits. RPA provides a platform for recruitment of factors required during replication, checkpoint regulation, DNA repair [including homologous recombination (HR), nucleotide excision repair (NER), base excision repair (BER) and mismatch repair (MMR)], telomere maintenance and retro-transposition. To understand the role of RPA in breast cancer pathogenesis we conducted a comprehensive genomic, transcriptomic, bioinformatic, proteomic and preclinical study. Patients and methods: RPA1, RPA2 and RPA3 protein expression was evaluated in 4221 primary invasive breast carcinomas and 776 breast ductal carcinoma in situ (DCIS). Transcriptomic investigation was completed in the METABRIC cohort (n=1980). Detailed bioinformatics was conducted in the TCGA cohort (n=1090). RPA deficient breast cancer cell lines were tested for Cisplatin, Palbociclib and Olaparib sensitivity. Results: RPA1, RPA2 and RPA3 loss is frequent in DCIS and linked to aggressive phenotype (including high grade, ER and PR negativity) (all p values < 0.01). DCIS with low RPA1 was also associated with poor local recurrence-free interval (p< 0.00001). In invasive breast cancers, low RPA1, low RPA2 and low RPA3 were all associated with larger size, lympho-vascular invasion, higher histological grade, high stage, ER negativity and poor breast cancer specific survival. Transcriptomic alterations in low RPA tumors included those genes involved in steroid hormone biosynthesis, chemical carcinogenesis, and drug metabolism. Pre-clinically, RPA deficient breast cancer cells were sensitive to Cisplatin and Palbociclib (CDK4/6 inhibitor) therapy compared to controls. Additionally, the PARP1 inhibitor Olaparib was synthetically lethal in RPA1 and RPA2 deficient cells compared to controls. Increased Olaparib sensitivity was associated with double strand breaks, S-phase cell cycle arrest and increased apoptosis. Conclusions: We provide the first comprehensive evidence that RPA loss is an early event during breast cancer pathogenesis and promotes aggressive phenotypes. Pre-clinically RPA deficient breast cancer cells were selectively toxic to Cisplatin, Palbociclib and Olaparib. Citation Format: Mashael A. Algethami, Michael Toss, Juliette Brownlie, Corinne L. Woodcock, Chandar Jaipal, AHMED SHOQAFI, Katia Mesquita, Adel Alblihy, Nigel Mongan, Emad Rakha, Jennie N. Jeyapalan, Srinivasan Madhusudan, Andrew R. Green. Unravelling the clinicopathological and functional significance of Replication Protein A (RPA) heterotrimeric complex in sporadic breast cancers [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-18.

Primary neuroendocrine invasive breast carcinoma: A case report and literature review

Primary neuroendocrine invasive breast carcinoma: A case report and literature review

Comparative Study on Clinicopathological Characteristics of Breast Cancer in Vietnam and Italy

Background: In Vietnam and Italy, breast cancer (BC) occurs in women more frequently than any other cancer. Vietnam has a substantially lower incidence of breast cancer than Italy, but a higher mortality rate. Most Vietnamese patients present to the hospital with severe tumors at the late stages of diagnosis. The purpose of this study was to compare clinicopathologic features, biomarkers, and subtypes of BC between Vietnamese women and Italian ones. Methods: The sample was collected from all Vietnamese patients undergoing surgery with the diagnosis of primary invasive breast carcinoma in Hue Central Hospital as well as Hue University Hospital in Vietnam during 1 year from April 2016 to April 2017, and from the same category of women in Sassari University Hospital, Italy during the year 2016. The study parameters in both groups consisted of age at diagnosis, tumor size, histologic grade, histologic type, axillary node status, stages of diagnosis, biomarkers (Estrogen Receptor - ER, Progesterone Receptor - PR, Ki-67 cell proliferation marker - Ki-67, Human epidermal growth factor receptor 2 - HER2), and molecular subtypes of BC. Results: 323 patients were collected in total (235 from Sassari, Italy, and 88 from Thua Thien - Hue province, Vietnam). Vietnamese patients were diagnosed at a younger age than Italian patients, at just 52.5 on average, while the figure for Italian was 62. The Vietnamese BC patients also had a bigger tumor in size, higher grade, more axillary node positivity as well as a later stage of disease in comparison with Italian ones. The proportion of ER-positive was higher in the Italian group than that in Vietnam (88.1 vs 55.7%). The high Ki-67 expression prevalence was significantly higher in Vietnamese patients compared with Italian (81.8 vs 45.1%). The HER2-positive rate in Vietnam was 33%, higher than that in Italy (8.1%). Histologic grade and cell proliferation index Ki-67 were significantly correlated with HER2 positivity in both groups. Conclusions: Vietnamese patients demonstrated more aggressive tumor features and worse prognostic biomarkers than Italian patients. The prevalence of HER2 positive and high Ki-67 expression in Vietnamese patients was considerably higher than in Italian patients. The remarkable differences in clinicopathological characteristics between the two populations suggest the diversity of biological tumor, ethnicity, and environment as well as the effectiveness of the screening program.

Chromatin accessibility landscape and active transcription factors in primary human invasive lobular and ductal breast carcinomas

BackgroundInvasive lobular breast carcinoma (ILC), the second most prevalent histological subtype of breast cancer, exhibits unique molecular features compared with the more common invasive ductal carcinoma (IDC). While genomic and transcriptomic features of ILC and IDC have been characterized, genome-wide chromatin accessibility pattern differences between ILC and IDC remain largely unexplored.MethodsHere, we characterized tumor-intrinsic chromatin accessibility differences between ILC and IDC using primary tumors from The Cancer Genome Atlas (TCGA) breast cancer assay for transposase-accessible chromatin with sequencing (ATAC-seq) dataset.ResultsWe identified distinct patterns of genome-wide chromatin accessibility in ILC and IDC. Inferred patient-specific transcription factor (TF) motif activities revealed regulatory differences between and within ILC and IDC tumors. EGR1, RUNX3, TP63, STAT6, SOX family, and TEAD family TFs were higher in ILC, while ATF4, PBX3, SPDEF, PITX family, and FOX family TFs were higher in IDC.ConclusionsThis study reveals the distinct epigenomic features of ILC and IDC and the active TFs driving cancer progression that may provide valuable information on patient prognosis.

MALINC1 an Immune-Related Long Non-Coding RNA Associated with Early-Stage Breast Cancer Progression.

Simple SummaryHere we characterize the phenotypic and molecular effects of MALINC1, a long non-coding RNA (lncRNA) that we found significantly upregulated in premalignant ductal carcinoma in-situ lesions. We provide evidence that MALINC1 behaves as an oncogenic and immune-related lncRNA involved with early-stage breast cancer progression, showing prognostic and predictive value to immunotherapy in invasive breast carcinomas.Long non-coding RNAs are increasingly being recognized as cancer biomarkers in various malignancies, acting as either tumor suppressors or oncogenes. The long non-coding MALINC1 intergenic RNA was identified as significantly upregulated in breast ductal carcinoma in situ. The aim of this study was to characterize MALINC1 expression, localization, and phenotypic and molecular effects in non-invasive and invasive breast cancer cells. We determined that MALINC1 is an estrogen–estrogen receptor-modulated lncRNA enriched in the cytoplasmic fraction of luminal A/B breast cancer cells that is associated with worse overall survival in patients with primary invasive breast carcinomas. Transcriptomic studies in normal and DCIS cells identified the main signaling pathways modulated by MALINC1, which mainly involve bioprocesses related to innate and adaptive immune responses, extracellular matrix remodeling, cell adhesion, and activation of AP-1 signaling pathway. We determined that MALINC1 induces premalignant phenotypic changes by increasing cell migration in normal breast cells. Moreover, high MALINC1 expression in invasive carcinomas was associated with a pro-tumorigenic immune environment and a favorable predicted response to immunotherapy both in luminal and basal-like subtypes compared with low-MALINC1-expression tumors. We conclude that MALINC1 behaves as an oncogenic and immune-related lncRNA involved with early-stage breast cancer progression.

ROS1 altered breast cancers - a distinctive molecular subtype of PR- metastatic breast cancers: Expanding the scope of targeted therapeutics.

Breast cancer, one of the leading causes of cancer-related mortality in women worldwide, exhibits wide-ranging histo-morphologic, clinical and molecular diversity. This study compares the genetic alterations of breast tumors with the histo-morphological, hormone receptor status and metastatic "organotropism". Twenty-two cases of primary invasive breast carcinoma with local/distant metastasis were retrieved from the pathology archives. The status of estrogen and progesterone receptors by immunohistochemistry was recorded along with other pertinent case data. Next generation sequencing was performed on formalin-fixed paraffin embedded blocks of tumor. The mean age of the study subjects was 57.9 ± 13.3 years. TP53 mutation was the most common gene alteration in this study and was seen in 40.9% cases. ROS1 gene was mutated in 44.4% PR negative breast cancers while being wild type in the twelve PR positive tumors. (p = 0.021).STRING interaction network constructed with ROS1 and PR revealed a significantly higher number of interactions in this network than expected (p-value 0.000973). This study highlights the significantly higher incidence of ROS1 gene alterations in metastatic PR- breast cancers, with STRING network analysis revealing higher nodal interaction in the nodal network comprised of PR and ROS1 exclusive of ER.

5-Aminolevulinic Acid-mediated Photodynamic Therapy on Primary Bone Tumor and Bone Metastases Cell Lines.

Bone metastases are associated with poor prognosis and low quality of life for the affected patients. Photodynamic therapy (PDT) emerges as a noninvasive therapy that can target local metastatic bone lesions. This paper presents an in vitro method to study the PDT effect in adherent cell lines. To this end, we demonstrate a step-by-step approach to subject both primary (giant cell bone tumor) and human bone metastatic cancer cell lines (derived from a primary invasive ductal breast carcinoma and renal carcinoma) to 5-aminolevulinic acid (5-ALA)-mediated PDT. After 24 h post 5-ALA-PDT irradiation (blue light-wavelength 436 nm), the therapeutic effect was assessed in terms of cell migration potential, viability, apoptotic features, and cellular growth arrest (senescence). Post 5-ALA-PDT irradiation, musculoskeletal-derived cell lines respond differently to the same doses and exposure of PDT. Depending on the extent of cellular damage triggered by PDT exposure, two different cell fates-apoptosis and senescence were noted. Variable sensitivity to PDT therapy among different bone cancer cell lines provides useful information for selecting more appropriate PDT settings in clinical settings. This protocol is designed to exemplify the use of PDT in the context of musculoskeletal neoplastic cell lines. It may be adjusted to investigate the therapeutic effect of PDT on various cancer cell lines and various photosensitizers and light sources.

Unusual staining of immunohistochemical markers PAX8 and CDX2 in breast carcinoma: a potential diagnostic pitfall

Knowing the sensitivity and specificity of tissue-specific immunohistochemical markers is crucial for accurate determination of the primary tumor site. PAX8 has been used as a diagnostic marker for carcinomas of the gynecologic tract, kidney, and thyroid gland, and CDX2 has been used as a marker of gastrointestinal carcinoma. Neither is considered a marker for breast carcinoma (BC). However, we have encountered BCs that express PAX8 or CDX2, some of which caused diagnostic confusion. We investigated the immunohistochemical staining frequency of PAX8 and CDX2 in BC. We identified 237BCs for which PAX8 staining results were reported (102 primary and 135 metastatic BCs); seven primary and four metastatic BCs (4.6%) were positive for PAX8, with various intensities and staining patterns. CDX2 staining results were reported for 271BCs (78 primary and 193 metastatic); four primary BCs and one metastatic BC (1.8%) were positive for CDX2, ranging from focal and weak to diffuse and strong. We also stained primary invasive BCs with PAX8 and CDX2 using tissue microarrays. None of the 332 PAX8-stained cases was positive, while one of 143 CDX2-stained cases was positive. Four PAX8-positive and three CDX2-positive cases were stained with TRPS1, and all were positive for TRPS1. In addition, we reviewed the literature for PAX8 and CDX2 expression in BCs and found 5.5% PAX8-positive BCs (90/1625) in 17 studies and 0.8% CDX-2 positive BCs (7/909) in 20 studies. PAX8 and CDX2 are infrequently expressed in BC by immunohistochemistry, and in rare cases, the staining can be strong and diffuse. Additional diagnostic markers are necessary and helpful in distinguishing breast from other primary origins.