Implementation of TMA and digitalization in routine diagnostics of breast pathology

Unlocking breast cancer in Brazilian public health system: Using tissue microarray for accurate immunohistochemical evaluation with limitations in subtyping

BACKGROUND

Breast cancer (BC) is a significant burden on healthcare systems, especially in low- and middle-income countries where access to diagnosis and treatment is challenging.

OBJECTIVES

The purpose of this study was to assess the diagnostic accuracy and cost using tissue microarray (TMA) instead of traditional immunohistochemical (IHC) evaluation for estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), and the proliferation marker Ki-67 and BC subtyping within the Brazilian public health system.

DESIGN

This is a retrospective cohort study comparing TMA slides with traditional whole-slide evaluation for IHC markers in 242 BC cases.

METHODS

We used formalin-fixed tissue blocks for TMA assembly. Clinical data and IHC scores for ER, PR, HER2, and Ki-67 were obtained from pathology reports. Cohen's kappa (k) was used to assess TMA performance.

RESULTS

BC samples were distributed in 10 TMAs and 968 cores were scored (242 BC cases × 4 markers). In 97% of these, TMA reached high quality to adequate IHC scoring with minimal technical issues. Inter-examiner agreement was almost perfect for all markers (ranging from 0.85 for HER2 to 0.91 for ER, p < 0.001). The intratumoral heterogeneity ranged from almost perfect agreement for ER and HER2 to moderate to substantial for PR and Ki-67. TMA offers substantial time and cost savings, with an approximately 11-fold reduction compared to traditional methods. The concordance between TMA and original reports was almost perfect, with 93% overall agreement (k = 0.81, p < 0.001). However, TMA performance varied between markers, with intratumoral heterogeneity significantly impacting discordant results, particularly for Ki-67 and HER2. This ultimately affected the accuracy of BC subtyping. TMA performed well in identifying luminal A and triple-negative cases, but misclassification was common for luminal B and HER2-positive cases.

CONCLUSION

TMA offers accurate and lower-cost results in the individualized IHC assessment of BC markers. However, we do not recommend the use of TMA in the subtyping of BC, where analysis of the whole section remains necessary for more accurate results. We advocate more studies using the TMA approach in the Brazilian public health system to advance women's health care.

Optimization of tissue microarray technique for breast cancer patients: a short communication

Background

Tissue microarray (TMA) is a novel technique for studying different types of cancer tissues in one block. TMA is not yet established in Syria, so we aimed in this project to apply and set the most optimal conditions of TMA creation of breast cancer tissues at the Pathology Department of our institute.

Materials and Methods

Eighty-eight blocks of breast cancer tissues were selected, considering the inclusion criteria. The tissue specimens of breast cancer patients were manually placed in the block by punching a core from a paraffin block, which was then released into a recipient block using a small trocar. Three different conditions were tested on the constructed TMA block.

Results

We determined the most effective parameters that proved high quality: incubating the newly constructed block at a temperature of 43°C for 24 h in the oven and then cutting it the next day after cooling it to room temperature; also, cutting with a 5 μm thickness created the preferable stained slides later. CD3 staining showed high expression of tumor-infiltrating lymphocytes among triple-negative breast cancer patients and high expression of CD3 in triple-negative cancer patients.

Conclusion

The optimization of parameters presented in our study resulted in perfect TMA generation and successful immunohistochemistry staining for cancer research at our institution.

Multigene profiles to guide the use of neoadjuvant chemotherapy for breast cancer: a Copenhagen Breast Cancer Genomics Study

Estrogen receptor (ER) and human epidermal growth factor 2 (HER2) expression guide the use of neoadjuvant chemotherapy (NACT) in patients with early breast cancer. We evaluate the independent predictive value of adding a multigene profile (CIT256 and PAM50) to immunohistochemical (IHC) profile regarding pathological complete response (pCR) and conversion of positive to negative axillary lymph node status. The cohort includes 458 patients who had genomic profiling performed as standard of care. Using logistic regression, higher pCR and node conversion rates among patients with Non-luminal subtypes are shown, and importantly the predictive value is independent of IHC profile. In patients with ER-positive and HER2-negative breast cancer an odds ratio of 9.78 (95% CI 2.60;36.8), P < 0.001 is found for pCR among CIT256 Non-luminal vs. Luminal subtypes. The results suggest a role for integrated use of up-front multigene subtyping for selection of a neoadjuvant approach in ER-positive HER2-negative breast cancer.

Digital image analysis and assisted reading of the HER2 score display reduced concordance: pitfalls in the categorisation of HER2-low breast cancer

AIMS

Digital image analysis (DIA) is used increasingly as an assisting tool to evaluate biomarkers, including human epidermal growth factor receptor 2 (HER2) in invasive breast cancer (BC). DIA can assist pathologists in HER2 evaluation by presenting quantitative information about the HER2 staining in APP assisted reading (AR). Concurrently, the HER2-low category (HER2-1+/2+ without HER2 gene amplification) has gained prominence due to newly developed antibody-drug conjugates. However, major inter- and intraobserver variability have been observed for the entity. The present quality assurance study investigated the concordance between DIA and AR in clinical use, especially concerning the HER2-low category.

METHODS AND RESULTS

HER2 immunohistochemistry (IHC) in 761 tumours from 727 patients was evaluated in tissue microarray (TMA) cores by DIA (Visiopharm HER2-CONNECT) and AR. Overall concordance between HER2-scores were 73% (n = 552, weighted-κ: 0.66), and 88% (n = 669, weighted-κ: 0.70), when combining HER2-0/1+. A total of 205 scores were discordant by one category, while four were discordant by two categories. A heterogeneous HER2 pattern was relatively common in the discordant cases and a pitfall in the categorisation of HER2-low BC. AR more commonly reassigned a lower HER2 score (from HER2-1+ to HER2-0) within the HER2-low subgroup (n = 624) compared with DIA.

CONCLUSION

DIA and AR display moderate agreement with heterogeneous and aberrant staining, representing a source of discordance and a pitfall in the evaluation of HER2.

Inter-observer agreement of tumor infiltrating lymphocytes in primary HER2-positive breast cancer and correlation between tissue microarray and full tumor-sections

Tumor infiltrating lymphocytes (TILs) have predictive and prognostic potential in HER2-positive breast cancer (HER2 + BC). Due to tumor heterogeneity, guidelines recommend evaluation on full tumor-sections over biopsies, but aren't clear regarding tissue microarrays (TMAs). Herein, we investigate the inter-observer agreement of TILs assessment in HER2 + BC on full-sections and TMAs using a standardized method. Two pathologists assessed TILs using HE full-sections and TMAs from 244 patients with HER2 + BC. TILs were assessed in 10% intervals; values <10% evaluated as 0%, 1% or 5%. Levels of agreement were evaluated using intraclass-coefficient (ICC), Kappa statistics and concordance analysis. For inter-observer agreement for full-sections, ICC was 0.93 (95% CI 0.89-0.95) and Kappa was 0.75, corresponding to acceptable and moderate agreement respectively. For TMAs, ICC was 0.73 (95% CI: 0.62-0.81) and Kappa 0.33, corresponding to unacceptable agreement. For association in matched TMA and full-sections, ICC was 0.64 (95% CI 0.55-0.71) and Lin's concordance correlation coefficient was 0.63 (95% CI 0.55-0.71), corresponding to unacceptable agreement. There is acceptable inter-observer agreement of TILs assessment on full-sections but not TMAs and discrepancy between full-sections and TMAs. TMA preparation must include consideration for representation of both entire tumor area and tumor-microenvironment to correctly define prognostic and predictive values of potential immuno-related biomarkers.

Identifying mismatch repair-deficient colon cancer: near-perfect concordance between immunohistochemistry and microsatellite instability testing in a large, population-based series

AIMS

Establishing the mismatch repair (MMR) status of colorectal cancers is important to enable the detection of underlying Lynch syndrome and inform prognosis and therapy. Current testing typically involves either polymerase chain reaction (PCR)-based microsatellite instability (MSI) testing or MMR protein immunohistochemistry (IHC). The aim of this study was to compare these two approaches in a large, population-based cohort of stage 2 and 3 colon cancer cases in Northern Ireland.

METHODS AND RESULTS

The study used the Promega pentaplex assay to determine MSI status and a four-antibody MMR IHC panel. IHC was applied to tumour tissue microarrays with triplicate tumour sampling, and assessed manually. Of 593 cases with available MSI and MMR IHC results, 136 (22.9%) were MSI-high (MSI-H) and 135 (22.8%) showed abnormal MMR IHC. Concordance was extremely high, with 97.1% of MSI-H cases showing abnormal MMR IHC, and 97.8% of cases with abnormal IHC showing MSI-H status. Under-representation of tumour epithelial cells in samples from heavily inflamed tumours resulted in misclassification of several cases with abnormal MMR IHC as microsatellite-stable. MMR IHC revealed rare cases with unusual patterns of MMR protein expression, unusual combinations of expression loss, or secondary clonal loss of expression, as further illustrated by repeat immunostaining on whole tissue sections.

CONCLUSIONS

MSI PCR testing and MMR IHC can be considered to be equally proficient tests for establishing MMR/MSI status, when there is awareness of the potential pitfalls of either method. The choice of methodology may depend on available services and expertise.

Clinical implications of intrinsic molecular subtypes of breast cancer for sentinel node status

Axillary lymph node status is an important prognostic factor for breast cancer patients and sentinel lymph node biopsy (SLNB) is a less invasive surgical proxy. We examined if consecutively derived molecular subtypes from primary breast cancers provide additional predictive value for SLNB status. 1556 patients with a breast cancer > 10 mm underwent primary surgical procedure including SLNB and tumor specimens were assigned with a transcriptomics-based molecular subtype. 1020 patients had a negative sentinel node (SN) and 536 a positive. A significant association between tumor size and SN status (p < 0.0001) was found across all samples, but no association between size and SN status (p = 0.14) was found for BasL tumors. A BasL subtype was a predictor of an SN-negative status (p = 0.001, OR 0.58, 95% CI 0.38;0.90) and among the BasL, postmenopausal status was a predictor for SN-negative status (p = 0.01). Overall survival was significantly lower (p = 0.02) in patients with BasL tumors and a positive SN. Interestingly, we identified a significant correlation between hormone receptor activity and SN status within the BasL subtype. Taken together, molecular subtypes and hormone receptor activity of breast cancers add predictive value for SLNB status.

Association of Cytokeratin 5 and Claudin 3 expression with BRCA1 and BRCA2 germline mutations in women with early breast cancer

BACKGROUND

It is important to identify biomarkers associated with BRCA mutation in women with early breast cancer (BC) to improve early identification of mutation carriers. Thus, in this study, we examined the protein expression of claudin (CLDN) 3, CLDN4, CLDN7, and E-cadherin. Moreover, we analyzed additional histopathological variables and their associations in familial BC.

METHODS

Immunohistochemical analysis for CLDNs and E-cadherin was performed on 237 BC cases of three different subsets of BC tumors: 62 from BRCA1 mutation carriers, 59 from BRCA2 mutation carriers, and 116 tumors from patients with BRCA wild type (WT) as controls. Histopathological data were also analyzed in the different subgroups. Logistic regression and receiver operation characteristic (ROC) curve were conducted to investigate factors associated with BRCA tumors.

RESULTS

Expression of CLDN3 positively correlated with BRCA-mutated BC. CLDN3 was expressed in 58% of BRCA1-mutated tumors compared to only 7% in BRCA2-mutated tumors (p < 0.001) and 1% in WT tumors (p < 0.001). CK5 and CK14 expression were also more likely to arise in BRCA1 tumors (44 and 16%, respectively) than in the control group (8 and 4%) (p < 0.001, p = 0.012, respectively). We also found a significantly higher proportion of CK5+ among BRCA1 tumors (44%) in comparison with BRCA2-related BC (8%) (p < 0.001). In addition, there was a significant difference between both groups regarding CK14: positive expression in 16 and 5%, respectively (p = 0.030). CK5 and CK14 did not differ between the BRCA2 group and the WT tumors significantly. In a multivariate regression model, expression of CK5 (Odds ratio (OR): 6.46; 95% confidence interval (CI): 1.52-27.43; p = 0.011), and CLDN3 (OR: 200.48; 95% CI: 21.52-1867.61; p < 0.001) were associated with BRCA1 mutation status.

CONCLUSIONS

Our data suggests that CLDN3, CK5, and CK14 in combination with ER, PR and HER2 are associated with BRCA1 mutation status.

Optimization of Tissue Microarrays from Banked Human Formalin-Fixed Paraffin Embedded Tissues in the Cancer Research Setting

The tissue microarray (TMA) is a powerful tool for cancer biomarker discovery and validation. Tens to hundreds of samples can be evaluated simultaneously for molecular marker status at the protein or nucleic acid level. Although fully automated or semiautomated technologies for TMA creation provide excellent precision with respect to core transfer, they do not obviate the need for technical expertise to successfully generate high-quality TMA blocks and derivative sections. We have leveraged our expanding bank of formalin-fixed paraffin embedded paired tumor and normal tissues in our academic cancer center to provide a rich source of input material for cancer research TMAs. In this study, we report a stepwise optimization of TMA generation parameters, including paraffin wax selection, tempering protocol, and sectioning conditions, to achieve the best ribbon sectioning.

Molecular subtyping of breast cancer improves identification of both high and low risk patients

BACKGROUND

Transcriptome analysis enables classification of breast tumors into molecular subtypes that correlate with prognosis and effect of therapy. We evaluated the clinical benefits of molecular subtyping compared to our current diagnostic practice.

MATERIALS AND METHODS

Molecular subtyping was performed on a consecutive and unselected series of 524 tumors from women with primary breast cancer (n = 508). Tumors were classified by the 256 gene expression signature (CIT) and compared to conventional immunohistochemistry (IHC) procedures.

RESULTS

More than 99% of tumors were eligible for molecular classification and final reports were available prior to the multidisciplinary conference. Using a prognostic standard mortality rate index (PSMRi) developed by the Danish Breast Cancer Group (DBCG) 39 patients were assigned with an intermediate risk and among these 16 (41%) were furthermore diagnosed by the multi-gene signature assigned with a luminal A tumor and consequently spared adjuvant chemotherapy. There was overall agreement between mRNA derived and IHC hormone receptor status, whereas IHC Ki67 protein proliferative index proved inaccurate, compared to the mRNA derived index. Forty-one patients with basal-like (basL) subtypes were screened for predisposing mutations regardless of clinical predisposition. Of those 17% carried pathogenic mutations.

CONCLUSION

Transcriptome based subtyping of breast tumors evidently reduces the need for adjuvant chemotherapy and improves identification of women with predisposing mutations. The results imply that transcriptome profiling should become an integrated part of current breast cancer management.

Digitized whole slides for breast pathology interpretation: current practices and perceptions

Digital whole slide imaging (WSI) is an emerging technology for pathology interpretation; however, little is known about pathologists' practice patterns or perceptions regarding WSI. A national sample (N = 252) of pathologists from New Hampshire, Vermont, Washington, Oregon, Arizona, Alaska, Maine, and Minnesota were surveyed in this cross-sectional study (2011-2013). The survey included questions on pathologists' experience, WSI practice patterns, and perceptions using a six-point Likert scale. Agreement was summarized with descriptive statistics to characterize pathologists' use and perceptions of WSI. The majority of participating pathologists were males (63%) between 40 and 59 years of age (70%) and not affiliated with an academic medical center (72%). Experience with WSI was reported by 49%. Types of use reported included CME/board exams/teaching (28%), tumor board/clinical conference (22%), archival purposes (6%), consultative diagnosis (4%), research (4%), and other uses (12%). Most respondents (79%) agreed that accurate diagnoses can be made with this technology, and that WSI is useful for obtaining a second opinion (88%). However, 78% of pathologists agreed that digital slides are too slow for routine clinical interpretation. Fifty-nine percent agreed that the benefits of WSI outweigh concerns. The respondents were equally split as to whether they would like to adopt WSI (51%) or not (49%). About half of pathologists reported experience with the WSI technology, largely for CME, licensure/board exams, and teaching. Positive perceptions regarding WSI slightly outweigh negative perceptions. Understanding practice patterns with WSI as dissemination advances may facilitate concordance of perceptions with adoption of the technology.

Comparison of Fluorescence In Situ Hybridization and Chromogenic In Situ Hybridization for Low and High Throughput HER2 Genetic Testing

The purpose was to evaluate and compare 5 different HER2 genetic assays with different characteristics that could affect the performance to analyze the human epidermal growth factor 2 (HER2) gene copy number under low and high throughput conditions. The study included 108 tissue samples from breast cancer patients with HER2 immunohistochemistry (IHC) results scored as 0/1+, 2+, and 3+. HER2 genetic status was analysed using chromogenic in situ hybridization (CISH) and fluorescence in situ hybridization (FISH). Scoring results were documented through digital image analysis. The cancer region of interest was identified from a serial H&E stained slide following tissue cores were transferred to a tissue microarrays (TMA). When using TMA in a routine flow, all patients will be tested for HER2 status with IHC followed by CISH or FISH, thereby providing individual HER2 results. In conclusion, our results show that the differences between the HER2 genetic assays do not have an effect on the analytic performance and the CISH technology is superior to high throughput HER2 genetic testing due to scanning speed, while the IQ-FISH may still be a choice for fast low throughput HER2 genetic testing.

Tissue microarray analysis as a screening tool for neuroendocrine carcinoma of the breast

Neuroendocrine carcinoma of the breast (NCB) is a fairly recent diagnostic entity added by WHO in 2003. Since then, studies have indicated that NCB potentially displays a worse prognosis than invasive ductal carcinoma. However, due to a lack of standard use of immunohistochemical staining for neuroendocrine markers and the fact that NCB may only show slight neuroendocrine morphology that can easily be overlooked, NCB is often underdiagnosed. Consequently, there is a need for fast and reliable detection method for NCB. Here, we take a first step toward finding an easy way of identifying NCB by investigating the usefulness of tissue microarray (TMA) analysis as a screening tool. We present our findings with regard to sensitivity and specificity compared with whole-mount sections. The material consists of 240 cases of breast cancer divided into 20 TMA blocks that were all immunohistochemically stained for the neuroendocrine markers chromogranin A and synaptophysin. Cases positive in more than 50% of the tumor cells were accepted in accordance with WHO (2003) standards of NCB. Sensitivity and specificity for TMA sections vs whole-mount sections were found to be 100% and 97.8%, respectively, suggesting that TMA analysis is a reliable method for NCB detection.

Reliability of receptor assessment on core needle biopsy in breast cancer patients

We compared the breast core needle biopsy and the resection specimen with respect to estrogen (ER), progesterone (PR) and human epidermal growth factor receptor 2 (HER2) status to identify predictors for discordant findings. We retrospectively collected data from 526 newly diagnosed breast cancer patients. ER, PR and HER2 status had been assessed in both the core needle biopsy and resection specimen. The assessment of ER by immunohistochemistry (IHC) in core needle biopsy was false negative in 26.5% and false positive in 6.8% of patients. For the PR status the false negative and false positive results of core needle biopsy were 29.6% and 10.3%, respectively. The results of the HER2 status, as determined by IHC and silver in situ hybridization (SISH), were false negative in 5.4% and false positive in 50.0%. We need to be aware of the problem of false negative and false positive test results in ER, PR and HER2 assessment in core needle biopsy and the potential impact on adjuvant systemic treatment. With current techniques, we recommend using the resection specimen to measure these receptors in patients without neoadjuvant treatment. A better alternative might be the use of tissue microarray, combining both core needle biopsy and resection specimen.