A Pilot Validation Study Comparing Fluorescence-Imitating Brightfield Imaging, A Slide-Free Imaging Method, With Standard Formalin-Fixed, Paraffin-Embedded Hematoxylin-Eosin-Stained Tissue Section Histology for Primary Surgical Pathology Diagnosis

CONTEXT.—

Digital pathology using whole slide images has been recently approved to support primary diagnosis in clinical surgical pathology practices. Here we describe a novel imaging method, fluorescence-imitating brightfield imaging, that can capture the surface of fresh tissue without requiring prior fixation, paraffin embedding, tissue sectioning, or staining.

OBJECTIVE.—

To compare the ability of pathologists to evaluate direct-to-digital images with standard pathology preparations.

DESIGN.—

One hundred surgical pathology samples were obtained. Samples were first digitally imaged, then processed for standard histologic examination on 4-μm hematoxylin-eosin-stained sections and digitally scanned. The resulting digital images from both digital and standard scan sets were viewed by each of 4 reading pathologists. The data set consisted of 100 reference diagnoses and 800 study pathologist reads. Each study read was compared to the reference diagnosis, and also compared to that reader's diagnosis across both modalities.

RESULTS.—

The overall agreement rate, across 800 reads, was 97.9%. This consisted of 400 digital reads at 97.0% versus reference and 400 standard reads versus reference at 98.8%. Minor discordances (defined as alternative diagnoses without clinical treatment or outcome implications) were 6.1% overall, 7.2% for digital, and 5.0% for standard.

CONCLUSIONS.—

Pathologists can provide accurate diagnoses from fluorescence-imitating brightfield imaging slide-free images. Concordance and discordance rates are similar to published rates for comparisons of whole slide imaging to standard light microscopy of glass slides for primary diagnosis. It may be possible, therefore, to develop a slide-free, nondestructive approach for primary pathology diagnosis.

The Biomarker Ki-67: Promise, Potential, and Problems in Breast Cancer

Ki-67 is a nuclear protein serendipitously discovered by monoclonal antibody selection in the early 1980s. While it has been applied for decades in the context of breast cancer as a putative prognostic and, more recently, predictive, biomarker, even after all this time there is incomplete agreement as to the validity of the immunohistochemical assays employed for Ki-67 assessment, given possible effects of the disparate methodologies employed and possible confounding preanalytical, analytical, and interpretive variables. In this brief review, the history of Ki-67 and the problems, particularly with the analytical and interpretive variables, are highlighted through a selective review of the published literature. The contributions of the International Ki-67 Breast Cancer Working Group are highlighted, and in particular, the recommendations made by this group are reviewed. The potential of Ki-67 as a biomarker for breast cancer has not yet been fully realized, but an understanding of the power as well as the limitations of the methods of Ki-67 assessment are important if this biomarker can realize its potential.

Systematically higher Ki67 scores on core biopsy samples compared to corresponding resection specimen in breast cancer: a multi-operator and multi-institutional study

Ki67 has potential clinical importance in breast cancer but has yet to see broad acceptance due to inter-laboratory variability. Here we tested an open source and calibrated automated digital image analysis (DIA) platform to: (i) investigate the comparability of Ki67 measurement across corresponding core biopsy and resection specimen cases, and (ii) assess section to section differences in Ki67 scoring. Two sets of 60 previously stained slides containing 30 core-cut biopsy and 30 corresponding resection specimens from 30 estrogen receptor-positive breast cancer patients were sent to 17 participating labs for automated assessment of average Ki67 expression. The blocks were centrally cut and immunohistochemically (IHC) stained for Ki67 (MIB-1 antibody). The QuPath platform was used to evaluate tumoral Ki67 expression. Calibration of the DIA method was performed as in published studies. A guideline for building an automated Ki67 scoring algorithm was sent to participating labs. Very high correlation and no systematic error (p = 0.08) was found between consecutive Ki67 IHC sections. Ki67 scores were higher for core biopsy slides compared to paired whole sections from resections (p ≤ 0.001; median difference: 5.31%). The systematic discrepancy between core biopsy and corresponding whole sections was likely due to pre-analytical factors (tissue handling, fixation). Therefore, Ki67 IHC should be tested on core biopsy samples to best reflect the biological status of the tumor.

Phosphorylated transducer and activator of transcription-3 (pSTAT3) immunohistochemical expression in paired primary and metastatic colorectal cancer

BACKGROUND

Signal Transducer and Activator of Transcription-3 (STAT3) mediates cellular functions. We assessed the IHC expression of phosphorylated STAT3 (pSTAT3) in paired primary tumors and liver metastases in patients with advanced stage colorectal cancer (CRC).

METHODS

We included patients with tissue blocks available from both the primary CRC and a surgically resected liver metastasis. The IHC pSTAT3 expression agreement was measured using Cohen's kappa statistic.

RESULTS

The study included 103 patients, 55% male, median age was 64. 43% tumors originated in rectum, and 63% of the primary tumors were synchronous. Expression of pSTAT3 was 76% in liver metastases and 71% in primary tumors. A difference in pSTAT3 staining between the primary tumor and liver metastases was noted in 64%. There was lost expression of pSTAT3 in the liver metastases in 28% and gained expression in 36% of cases compared to the primary. The kappa statistic comparing agreement between staining patterns of the primary tumors and liver metastases was a "less-than-chance", at -0.02. Median survival was 4.9 years, with no difference in survival outcomes by pSTAT3 expression in the primary tumor or liver metastases.

DISCUSSION

STAT3 is not a prognostic marker in the selective setting of metastatic CRC to liver, but it may remain a potential therapeutic target given most liver metastases expressed pSTAT3. Discordant pSTAT3 expression in between primary tumors and paired liver metastases suggests that use of this class of drug to treat liver predominant metastatic colorectal cancer in a biomarker-driven approach may require confirmatory liver tumor biopsy.

Abstract P5-02-01: Analytical validation and prognostic potential of an automated digital scoring protocol for Ki67: An International Ki67 Working Group study

Background: The nuclear proliferation biomarker Ki67 has multiple potential roles in breast cancer, including aiding decisions based on prognosis, but has unacceptable between-laboratory variability. Here we tested an open source and calibrated automated digital image analysis (DIA) platform to: (i) Assess inter-laboratory reproducibility of automated Ki67 measurement among 17 participating labs and compare those with standardized pathologist-based visual scoring. (ii) Investigate the comparability of Ki67 measurement across corresponding core biopsy and whole section cases. (iii) Test prognostic potential of the built Ki67 scoring algorithms on an independent cohort.

Methods: Two sets of 60 previously stained slides containing 30 core-cut biopsy and 30 corresponding whole tumor sections from 30 ER+ breast cancer cases were sent to 17 participating labs for automated assessment of average Ki67 expression. The blocks were centrally cut and stained for Ki67 using the Mib-1 antibody. The QuPath (open-source software) DIA platform was used to evaluate tumoral Ki67 expression. Calibration of the DIA method was performed in our previous study (Acs et al, Lab Invest 2019). A detailed guideline for building an automated Ki67 scoring algorithm was sent to the participating labs. Visual scoring of average Ki67 expression was performed by pathologists according to published standardized methods (Leung et al, NPJ Br Cancer 2016; Leung et al, Histopath 2019). Locked down DIA Ki67 scoring algorithms were applied to a validation cohort: 222 breast cancer cases from the Karolinska University Hospital in whole section format. Sufficient reproducibility to declare analytical validity was defined as an Intra Class Correlation (ICC) with lower limit of 95% credible interval (CI) >0.80. Markov Chain Monte Carlo routines for generalized linear mixed models were used to estimate ICCs and calculate corresponding CIs.

Results: The same-section ICC was 0.902 (CI: 0.852-0.949) across 17 labs using calibrated DIA platform on core biopsy slides and 0.845 (CI: 0.778-0.912) on whole sections. The different-section ICC across the 17 labs was 0.873 (CI: 0.806-0.932) scoring on core biopsy slides and 0.777 (CI: 0.670-0.874) on whole sections. The pathologist-based visual Ki67 scoring showed ICC of 0.860 for all comparisons, respectively (CI: 0.795-0.927). Similar to what was observed for visual Ki67 scoring, the DIA scores are higher for core biopsy slides compared to paired whole sections (p≤0.001; median difference: 5.31%; IQR: 11.50%). Ki67 scores of all locked down DIA algorithms correlates significantly (p≤0.023) with outcome on the validation cohort (observed hazard ratios range: 2.518-2.922).

Conclusions: Automated Ki67 evaluation using a calibrated, open-source DIA platform (QuPath) met the pre-specified criterion of success on core biopsies but not on whole sections in the multi-institutional setting. The systematic discrepancy between core biopsy and corresponding whole sections was likely due to pre-analytical factors (tissue handling, fixation) and intratumor heterogeneity. We found that different algorithms built according to calibrated DIA methods had similar prognostic potential. Assessment of clinical utility is planned.

Citation Format: Balazs Acs, Samuel C.Y. Leung, Kelley M. Kidwell, Indu Arun, Renaldas Augulis, Sunil S. Badve, Yalai Bai, Anita L. Bane, John M.S. Bartlett, Jane Bayani, Gilbert Bigras, Annika Blank, Signe Borgquist, Henk Buikema, Martin C. Chang, Robin L. Dietz, Andrew Dodson, Anna Ehinger, Susan Fineberg, Cornelia M. Focke, Dongxia Gao, Allen M. Gown, Carolina Gutierrez, Johan Hartman, Judith C. Hugh, Zuzana Kos, Anne-Vibeke Lænkholm, Arvydas Laurinavicius, Richard M. Levenson, Rustin Mahboubi-Ardakani, Mauro G. Mastropasqua, Takuya Moriya, Sharon Nofech-Mozes, C. Kent Osborne, Liron Pantanowitz, Frédérique M. Penault-Llorca, Tammy Piper, Mary Anne Quintayo, Tilman T. Rau, Stefan Reinhard, Stephanie Robertson, Takashi Sakatani, Roberto Salgado, Melanie Spears, Jane Starczynski, Tomoharu Sugie, Bert van der Vegt, Giuseppe Viale, Shakeel Virk, Lila A. Zabaglo, Daniel F. Hayes, Mitch Dowsett, Torsten O. Nielsen, David L. Rimm, International Ki67 in Breast Cancer Working Group, BIG-NABCG. Analytical validation and prognostic potential of an automated digital scoring protocol for Ki67: An International Ki67 Working Group study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-02-01.

Analytical validation of a standardised scoring protocol for Ki67 immunohistochemistry on breast cancer excision whole sections: an international multicentre collaboration

AIMS

The nuclear proliferation marker Ki67 assayed by immunohistochemistry has multiple potential uses in breast cancer, but an unacceptable level of interlaboratory variability has hampered its clinical utility. The International Ki67 in Breast Cancer Working Group has undertaken a systematic programme to determine whether Ki67 measurement can be analytically validated and standardised among laboratories. This study addresses whether acceptable scoring reproducibility can be achieved on excision whole sections.

METHODS AND RESULTS

Adjacent sections from 30 primary ER⁺ breast cancers were centrally stained for Ki67 and sections were circulated among 23 pathologists in 12 countries. All pathologists scored Ki67 by two methods: (i) global: four fields of 100 tumour cells each were selected to reflect observed heterogeneity in nuclear staining; (ii) hot-spot: the field with highest apparent Ki67 index was selected and up to 500 cells scored. The intraclass correlation coefficient (ICC) for the global method [confidence interval (CI) = 0.87; 95% CI = 0.799-0.93] marginally met the prespecified success criterion (lower 95% CI ≥ 0.8), while the ICC for the hot-spot method (0.83; 95% CI = 0.74-0.90) did not. Visually, interobserver concordance in location of selected hot-spots varies between cases. The median times for scoring were 9 and 6 min for global and hot-spot methods, respectively.

CONCLUSIONS

The global scoring method demonstrates adequate reproducibility to warrant next steps towards evaluation for technical and clinical validity in appropriate cohorts of cases. The time taken for scoring by either method is practical using counting software we are making publicly available. Establishment of external quality assessment schemes is likely to improve the reproducibility between laboratories further.

Abstract P2-03-01: Analytical validation of a standardized scoring protocol for Ki67 assessed on breast excision whole sections: An international multicenter collaboration

Aims: (i) Determine whether between-observer reproducibility for Ki67 when assessed on whole sections according to a standardized scoring protocol is adequate for clinical application. (ii) Compare between-observer reproducibility of Ki67 scores assessed on hot-spots to scores using a global method that averages across a tissue section.

Background: The nuclear proliferation biomarker Ki67 has multiple potential roles in breast cancer, including aiding decisions based on prognosis, but unacceptable levels of between-laboratory variability have been observed. The International Ki67 in Breast Cancer Working Group has undertaken a systematic program to determine whether Ki67 measurement can be analytically validated and standardized across labs. In phase 1, variability in visual interpretation was identified as an important source of variability. Phases 2 and 3a showed that adherence to defined scoring methods substantially improved reproducibility in scoring tissue microarrays and core-cut biopsies. We now assess whether acceptable reproducibility can be achieved on whole sections.

Methods: Adjacent sections from 30 primary ER+ breast cancers were centrally stained for Ki67 to assemble 4 sets of 30 stained tumor sections, circulated around 23 labs in 12 countries. Ki67 was scored by 2 methods by all labs: (a) global: 4 fields of 100 tumor cells each were selected to reflect observed heterogeneity in nuclear staining (b) hot-spot: the field with highest Ki67 percentage of tumor cells with nuclear staining was selected and up to 500 cells scored. Ki67 scores were log2-transformed for statistical analyses and back-transformed for presentation. The primary objective was to assess whether either method could achieve an intraclass correlation coefficient (ICC) significantly greater than 0.8, considered substantial to almost-perfect reproducibility. Secondary objectives were to assess which method had highest observed ICC and to assess whether observers identified the same “hot-spots”.

Results: ICC for the global method was 0.87 (95%CI: 0.799-0.93), marginally meeting the prespecified success criterion. The ICC for the hot-spot method was 0.83 (95%CI: 0.74-0.90) and had a CI extending below the success criterion. Across the 23 labs, geometric mean value of the 30 scores ranged from 8.5 to 19.6 for the global method and from 12.8 to 30.3 for the hot-spot method. The overall mean (95% CI) of these values was 12.9 (11.9-14.0) and 20.9 (19.1-22.8), respectively. Visually, between-laboratory agreement in location of selected hot-spot varies between cases. The median times for scoring were 9 and 6 minutes for global and hot-spot methods respectively.

Conclusions: The global method marginally met the prespecified criterion of success; it should now be evaluated for clinical validity in appropriate cohorts of cases. The hot-spot method was observed to have slightly less reproducibility between labs. The time taken for scoring by either method is practical using counting software we are making publicly available. Establishment of external quality assessment schemes is likely to improve the reproducibility between labs further.

(Supported by a grant from the Breast Cancer Research Foundation)

Citation Format: Nielsen TO, Leung SCY, Zabaglo LA, Arun I, Badve SS, Bane AL, Bartlet JMS, Borgquist S, Chang MC, Dodson A, Ehinger A, Fineberg S, Focke CM, Gao D, Gown AM, Gutierrez C, Hugh JC, Kos Z, Lænkholm A-V, Mastropasqua MG, Moriya T, Nofech-Mozes S, Osborne CK, Penault-Llorca FM, Piper T, Sakatani T, Salgado R, Starczynski J, Sugie T, van der Vegt B, Viale G, Hayes DF, McShane LM, Dowsett M. Analytical validation of a standardized scoring protocol for Ki67 assessed on breast excision whole sections: An international multicenter collaboration [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-03-01.

Role of SATB2 in distinguishing the site of origin in glandular lesions of the bladder/urinary tract

The differential diagnosis of glandular lesions of the bladder/urinary tract can be challenging because of significant morphologic and immunohistochemical overlap between primary lesions and metastasis/direct extension from adjacent organs. Special AT-rich sequence-binding protein 2 (SATB2), encoded on chromosome 2q32-33, is a recently described DNA-binding protein involved in osteoblast lineage commitment and expressed in colorectal and appendiceal neoplasms. In this study, we hypothesized that immunohistochemistry for SATB2 may be of value in distinguishing primary adenocarcinoma of the bladder/urinary tract and urothelial carcinoma with glandular differentiation from gastrointestinal and endocervical primaries. Intensity and distribution of SATB2 nuclear labeling were semiquantitatively scored and compared with those of CDX2. The study included 43 primary adenocarcinomas of the bladder/urinary tract, 20 urothelial carcinomas with glandular differentiation, 26 adenocarcinomas of the uterine cervix, and 22 colorectal adenocarcinomas involving the bladder. Positive SATB2 immunostaining was observed in 21 of 43 (49%) primary bladder/urinary tract adenocarcinomas, in 17 of 22 (77%) colorectal adenocarcinomas, and in the glandular component of 4 of 18 (22%) urothelial carcinomas with glandular differentiation. SATB2 was negative in 25 of 26 endocervical adenocarcinomas and showed focal weak immunostaining (1+) in 1 of 26 (4%). The results were not significantly different from those seen with CDX2. We conclude that SATB2 immunohistochemistry is not useful in supporting urothelial versus gastrointestinal or endocervical origin in the differential diagnosis of glandular lesions of the bladder/urinary tract.

Guidelines for Pathologic Diagnosis of Malignant Mesothelioma 2017 Update of the Consensus Statement From the International Mesothelioma Interest Group

CONTEXT

- Malignant mesothelioma (MM) is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE

- To provide updated, practical guidelines for the pathologic diagnosis of MM.

DATA SOURCES

- Pathologists involved in the International Mesothelioma Interest Group and others with an interest and expertise in the field contributed to this update. Reference material included up-to-date, peer-reviewed publications and textbooks.

CONCLUSIONS

- There was discussion and consensus opinion regarding guidelines for (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) recognition of the key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiating epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas, and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid MM, (7) use of molecular markers in the diagnosis of MM, (8) electron microscopy in the diagnosis of MM, and (9) some caveats and pitfalls in the diagnosis of MM. Immunohistochemical panels are integral to the diagnosis of MM, but the exact makeup of panels employed is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Depending on the morphology, immunohistochemical panels should contain both positive and negative markers for mesothelial differentiation and for lesions considered in the differential diagnosis. Immunohistochemical markers should have either sensitivity or specificity greater than 80% for the lesions in question. Interpretation of positivity generally should take into account the localization of the stain (eg, nuclear versus cytoplasmic) and the percentage of cells staining (>10% is suggested for cytoplasmic and membranous markers). Selected molecular markers are now being used to distinguish benign from malignant mesothelial proliferations. These guidelines are meant to be a practical diagnostic reference for the pathologist; however, some new pathologic predictors of prognosis and response to therapy are also included.

Phosphorylated signal transducer and activator of transcription–3 (p-STAT3) expression concordance in paired primary and metastatic colorectal cancers (mCRC): Updated analysis

e15137

Background: p-STAT3 is a transcription factor which is associated with poor prognosis in multiple cancers. Overexpression of p-STAT3 by immunohistochemistry (IHC) in tumors of patients with mCRC is associated with more aggressive disease and decreased survival. Concordance of p-STAT3 expression in primary and metastatic tumors was assessed to determine the temporal heterogeneity of expression and correlation with clinical outcomes. Methods: Patients with tissue available from both primary and liver metastases were identified retrospectively. Tissue microarrays (TMA) were constructed using 2 x 2mm cores. Nuclear p-STAT3 expression intensity by IHC was graded as absent, low, or high. Primary outcome was concordance of p-STAT3 expression between primary and metastatic sites. Secondary outcome was correlation of p-STAT3 expression with disease outcomes. Results: 91 patients were identified: 55% were male, median age at diagnosis was 63, 60% had left-sided disease and 81% of metastases were synchronous. Expression of p-STAT3 in primary tumors was 23% high, 47% low and absent in 30% compared to 29% high, 50% low, and 21% absent in metastases. Concordant expression was observed in 23% of patients whereas it increased in 46% and decreased in 31% from primary to metastasis. Pearson’s correlation was 0.119 indicating a weak concordance. After a median follow-up of 7 years, 50 of 91 patients died. One-year and 5-year survival rates were 92% and 44% respectively, while the median overall survival (mOS) was 4.7 years [95%CI 3.1-6.4]. No significant prognostic correlation between primary or metastatic p-STAT3 expression and mOS was found. Conclusions: There was low concordance of p-STAT3 expression in primary and metastatic tumors of patients with mCRC. Tumor staining heterogeneity due to sampling of small cores included in TMA and predominance of synchronous metastases may play a role. Further research in the use of p-STAT3 as a biomarker in patients with mCRC is needed.

Diagnostic Immunohistochemistry: What Can Go Wrong and How to Prevent It

CONTEXT

-There are a number of critical factors that can lead to incorrect results if the diagnostic pathologist performing immunohistochemistry is unaware of, or not vigilant about, their influence.

OBJECTIVE

-To highlight 3 arenas in which errors may be introduced.

DATA SOURCES

-For choosing the correct primary antibody, selection of the most appropriate antibodies for a given clinical application can be aided by obtaining information from the vendor; however, this can yield incomplete information. There are a number of online databases that have comparisons of antibodies from different vendors, particularly with respect to their use and properties. Reading the published literature can assist in this process, particularly with respect to determining antibody sensitivity and specificity, but it is a daunting task to keep up with all of the immunohistochemistry-related papers published. Finally, Web sites of a number of quality assurance organizations are accessible and can provide a wealth of information comparing the "real world" performance characteristics of different antibodies to the same target protein. False-positive signals can result from a number of factors, including the use of inappropriately high antibody concentration, and "pseudospecific" signal that is in the wrong compartment of the cell. False-negative signal can result from factors such as use of a nonoptimized epitope retrieval method. It is critical that epitope retrieval methods be optimized for each antibody employed in the laboratory.

CONCLUSIONS

-By paying attention to these potential problems, the "black box" of diagnostic immunohistochemistry can be made more transparent.

Markers of metastatic carcinoma of breast origin

This review summarizes the three major breast-associated markers that can be of assistance in evaluating metastatic carcinomas for which a breast primary diagnosis is entertained. These markers include gross cystic disease fluid protein-15 (GCDFP-15), mammaglobin, and GATA3. The first two are cytoplasmic markers that show comparable sensitivities for breast cancer, although relatively few of the published studies have employed the same antibodies against the target molecule, making direct comparisons challenging. GATA3 is a nuclear transcription factor that shows superior sensitivity to GCDFP-15 and mammaglobin. However, the specificity of GATA3 can pose challenges, inasmuch as carcinomas of the bladder and other sites can show significant levels of positivity. Determination of the optimal panel of antibodies employed in a given clinical setting will thus depend on the non-breast tumours included in the differential diagnosis.

Investigation of PD-L1 Biomarker Testing Methods for PD-1 Axis Inhibition in Non-squamous Non-small Cell Lung Cancer

Inhibitors of the programmed cell death 1 (PD-1) signaling axis have recently demonstrated efficacy and are rapidly being incorporated into the treatment of non-small cell lung cancers (NSCLCs). Despite clear benefits to certain patients, the association of these responses with a predictive biomarker remains uncertain. Several different biomarkers have been proposed, with differing results and conclusions. This study compares multiple methods of biomarker testing for treatment of NSCLCs with PD1-axis inhibitors. Tissue microarrays of matched primary and metastatic NSCLCs were used to compare four different PD-1 ligand (PD-L1) IHC techniques, as well as RNA ISH. Additional cases with whole genome and transcriptome data were assessed for molecular correlates of PD-L1 overexpression. Eighty cases were included in the IHC study. Multiple IHC methodologies showed a high rate of agreement (Kappa = 0.67). When calibrated to RNA expression, agreement improved significantly (Kappa = 0.90, p=0.0049). PD-L1 status of primary and metastatic tumors was discordant in 17 (22%) cases. This study suggests that different IHC methodologies for PD-L1 assessment provide slightly different results. There is significant discordance between the PD-L1 status of primary tumors and lymph node metastases. RNA ISH may be a useful adjunct to complement PD-L1 IHC testing.

Analytical validation of a standardized scoring protocol for Ki67: phase 3 of an international multicenter collaboration

Pathological analysis of the nuclear proliferation biomarker Ki67 has multiple potential roles in breast and other cancers. However, clinical utility of the immunohistochemical (IHC) assay for Ki67 immunohistochemistry has been hampered by unacceptable between-laboratory analytical variability. The International Ki67 Working Group has conducted a series of studies aiming to decrease this variability and improve the evaluation of Ki67. This study tries to assess whether acceptable performance can be achieved on prestained core-cut biopsies using a standardized scoring method. Sections from 30 primary ER+ breast cancer core biopsies were centrally stained for Ki67 and circulated among 22 laboratories in 11 countries. Each laboratory scored Ki67 using three methods: (1) global (4 fields of 100 cells each); (2) weighted global (same as global but weighted by estimated percentages of total area); and (3) hot-spot (single field of 500 cells). The intraclass correlation coefficient (ICC), a measure of interlaboratory agreement, for the unweighted global method (0.87; 95% credible interval (CI): 0.81–0.93) met the prespecified success criterion for scoring reproducibility, whereas that for the weighted global (0.87; 95% CI: 0.7999–0.93) and hot-spot methods (0.84; 95% CI: 0.77–0.92) marginally failed to do so. The unweighted global assessment of Ki67 IHC analysis on core biopsies met the prespecified criterion of success for scoring reproducibility. A few cases still showed large scoring discrepancies. Establishment of external quality assessment schemes is likely to improve the agreement between laboratories further. Additional evaluations are needed to assess staining variability and clinical validity in appropriate cohorts of samples.

Evaluation of Human Epidermal Growth Factor Receptor 2 (HER2) Gene Status in Human Breast Cancer Formalin-Fixed Paraffin-Embedded (FFPE) Tissue Specimens by Fluorescence In Situ Hybridization (FISH)

Current standard of care requires that HER2 gene testing be performed on all newly diagnosed invasive breast cancers in order to determine eligibility for anti-HER2 antibody therapy and should be performed in accordance with current ASCO-CAP guidelines (Hammond et al., J Clin Oncol 29(15):e458, 2011; Wolff et al., J Clin Oncol 31(31):3997-4013, 2013). Here we describe a HER2 FISH methodology to evaluate HER2 gene status in FFPE breast tumor specimens.

Practical Applications in Immunohistochemistry: Carcinomas of Unknown Primary Site

CONTEXT

-Identification of the site of origin of carcinoma of unknown primary using immunohistochemistry is a frequent requirement of anatomic pathologists. Diagnostic accuracy is crucial, particularly in the current era of targeted therapies and smaller sample sizes.

OBJECTIVES

-To provide practical guidance and suggestions for classifying carcinoma of unknown primary using both proven and new antibodies, as well as targeting panels based on integration of morphologic and clinical features.

DATA SOURCES

-Literature review, the authors' practice experience, and authors' research.

CONCLUSIONS

-With well-performed and interpreted immunohistochemistry panels, anatomic pathologists can successfully identify the site of origin of carcinoma of unknown primary. It is crucial to understand not only the diagnostic uses of the many available antibodies but also the potential limits and pitfalls.

Vascular mesangial channels in human nodular diabetic glomerulopathy

The presence of vascular mesangial channels has been reported in idiopathic nodular glomerulosclerosis and diabetic glomerulopathy. However, only limited information on the morphology and immunohistochemical phenotype of these channels is available. This study aims to describe the light and electron microscopic features of these channels and delineate their immunohistochemical phenotype. Thirty-eight cases of human nodular diabetic glomerulopathy with mesangial channels identified by light microscopy were prospectively selected (2010-2012). The cases were stained with CD31/periodic acid-Schiff combined stain. Selected cases were immunostained for CD34, podoplanin, ERG, and Ki-67. Frequent, small and peripheral vascular mesangial channels were seen in all cases, whereas larger and more centrally located vascular channels were also observed. Communication between peripheral capillary loops and peripheral vascular mesangial channels was seen as was communication between peripheral and central vascular mesangial channels. The vascular mesangial channel lining cells showed a typical endothelial phenotype with strong expression of CD31, CD34, and ERG by immunohistochemistry. The lymphatic channel marker podoplanin was negative in all channels, and the proliferation marker Ki-67 showed no evidence of increased proliferation. By electron microscopy, mesangial channels show angulated, irregular borders with lining cells compatible with endothelium and surrounded by mesangial matrix. No basement membranes were identified surrounding the mesangial channels. These findings support the existence of vascular mesangial channels in nodular diabetic glomerulopathy and suggest neovascularization and altered blood flow within these glomeruli.

Personalized oncogenomics: clinical experience with malignant peritoneal mesothelioma using whole genome sequencing

Peritoneal mesothelioma is a rare and sometimes lethal malignancy that presents a clinical challenge for both diagnosis and management. Recent studies have led to a better understanding of the molecular biology of peritoneal mesothelioma. Translation of the emerging data into better treatments and outcome is needed. From two patients with peritoneal mesothelioma, we derived whole genome sequences, RNA expression profiles, and targeted deep sequencing data. Molecular data were made available for translation into a clinical treatment plan. Treatment responses and outcomes were later examined in the context of molecular findings. Molecular studies presented here provide the first reported whole genome sequences of peritoneal mesothelioma. Mutations in known mesothelioma-related genes NF2, CDKN2A, LATS2, amongst others, were identified. Activation of MET-related signaling pathways was demonstrated in both cases. A hypermutated phenotype was observed in one case (434 vs. 18 single nucleotide variants) and was associated with a favourable outcome despite sarcomatoid histology and multifocal disease. This study represents the first report of whole genome analyses of peritoneal mesothelioma, a key step in the understanding and treatment of this disease.

The lung-restricted marker napsin A is highly expressed in clear cell carcinomas of the ovary

OBJECTIVES

We recently observed expression of the "lung" marker napsin A in ovarian clear cell carcinomas and therefore sought to determine the extent of napsin A expression in a subset of ovarian neoplasms.

METHODS

We identified an archival series of ovarian clear cell carcinomas (n = 36), serous borderline tumors (n = 21), high-grade serous carcinomas (n = 37), and endometrioid adenocarcinomas (n = 29). Using standard immunohistochemical techniques on whole sections of formalin-fixed, paraffin-embedded specimens, we employed a panel of antibodies: napsin A (IP64), estrogen receptor (SP1), WT-1 (6F-H2), PAX-8 (BC12), and TTF-1 (SPT24).

RESULTS

Thirty-six of 36 clear cell carcinomas showed napsin A expression, typically in a uniform pattern. None of the serous borderline tumors or high-grade serous carcinomas manifested napsin A expression. Napsin A was expressed in three (10%) of 29 endometrioid adenocarcinomas, generally in a focal pattern.

CONCLUSIONS

Our study showed that napsin A is an extremely sensitive (100%) marker of ovarian clear cell carcinomas and exhibits very high specificity (100%) in distinguishing clear cell carcinomas from high-grade serous carcinomas and serous borderline tumors and 90% specificity in discriminating clear cell carcinomas from endometrioid carcinomas.

Evaluation of contemporary prostate and urothelial lineage biomarkers in a consecutive cohort of poorly differentiated bladder neck carcinomas

OBJECTIVES

New immunohistochemical (IHC) markers of urothelial carcinoma (UCa) and prostatic adenocarcinoma (PCa) have emerged in recent years, yet comparative studies to establish markers remain lacking. We aimed to identify an effective but parsimonious approach for poorly differentiated bladder neck lesions, to establish a best practice panel approach in a setting simulating prospective use.

METHODS

We tested the performance of a panel of IHC markers on whole sections of a consecutive cohort of transurethral resection specimens of poorly differentiated, challenging bladder neck resections (n=36).

RESULTS

In the setting of poorly differentiated bladder neck carcinomas, biomarker sensitivities for UCa were as follows: GATA3, 100%; S100P, 88%; p63, 75%; and cytokeratin (CK) 5/6, 56%; specificities of each were 100%. CK7 and CK20 showed sensitivities of 75% and 63%, though these were only 85% and 80% specific. For PCa markers, NKX3.1, p501S, prostate-specific membrane antigen, and androgen receptor (AR) each showed 100% sensitivity, outperforming ERG (35%) and prostate-specific antigen (PSA; 25%). All the prostate histogenesis markers were 100% specific, except for AR, which was positive in 13% of the UCa cases.

CONCLUSIONS

Novel IHC markers show improved diagnostic performance that enables positive and negative support for identifying histogenesis with the use of as few as two markers for this critical therapeutic distinction. PSA underperforms newer markers.

An international Ki67 reproducibility study

BACKGROUND

In breast cancer, immunohistochemical assessment of proliferation using the marker Ki67 has potential use in both research and clinical management. However, lack of consistency across laboratories has limited Ki67's value. A working group was assembled to devise a strategy to harmonize Ki67 analysis and increase scoring concordance. Toward that goal, we conducted a Ki67 reproducibility study.

METHODS

Eight laboratories received 100 breast cancer cases arranged into 1-mm core tissue microarrays-one set stained by the participating laboratory and one set stained by the central laboratory, both using antibody MIB-1. Each laboratory scored Ki67 as percentage of positively stained invasive tumor cells using its own method. Six laboratories repeated scoring of 50 locally stained cases on 3 different days. Sources of variation were analyzed using random effects models with log2-transformed measurements. Reproducibility was quantified by intraclass correlation coefficient (ICC), and the approximate two-sided 95% confidence intervals (CIs) for the true intraclass correlation coefficients in these experiments were provided.

RESULTS

Intralaboratory reproducibility was high (ICC = 0.94; 95% CI = 0.93 to 0.97). Interlaboratory reproducibility was only moderate (central staining: ICC = 0.71, 95% CI = 0.47 to 0.78; local staining: ICC = 0.59, 95% CI = 0.37 to 0.68). Geometric mean of Ki67 values for each laboratory across the 100 cases ranged 7.1% to 23.9% with central staining and 6.1% to 30.1% with local staining. Factors contributing to interlaboratory discordance included tumor region selection, counting method, and subjective assessment of staining positivity. Formal counting methods gave more consistent results than visual estimation.

CONCLUSIONS

Substantial variability in Ki67 scoring was observed among some of the world's most experienced laboratories. Ki67 values and cutoffs for clinical decision-making cannot be transferred between laboratories without standardizing scoring methodology because analytical validity is limited.

Diagnostic Approach to Hepatic Mass Lesions and Role of Immunohistochemistry

This review provides an overview of various hepatic mass lesions and a practical diagnostic approach, including most recent immunohistochemical stains used in clinical practice. A wide variety of benign and malignant lesions present as hepatic masses, and the differential diagnosis varies. In cirrhotic liver, the commonest malignant tumor is hepatocellular carcinoma (HCC), which needs to be differentiated from macroregenerative nodules, dysplastic nodules, and other tumors. The differential diagnosis of lesions in noncirrhotic liver in younger patients includes hepatic adenoma (HA), focal nodular hyperplasia (FNH), HCC, and other primary hepatic neoplasms and metastases. In older populations, metastases remain the most common mass lesions.

Abstract P1-07-01: Attainment of extremely high concordance rates between fluorescence in situ hybridization and immunohistochemistry in testing for human epidermal growth factor receptor 2 (HER2) in breast cancer using a normalized scoring system for immunohistochemistry: a four year experience with over 9000 cases

Background: The 2007 ASCO-CAP guidelines mandate a high level (95%) of concordance between different testing modalities such as fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) for demonstration of the human epidermal growth factor receptor 2 (HER2) status in breast cancer. As few laboratories had been able to attain this level of concordance, the ASCO-CAP guidelines mandated regulation of pre-analytical variables such as fixation time in an attempt to improve concordance. We wished to test our hypothesis that the major reason for discordance between IHC and FISH results is false positive IHC, i.e., IHC 3+ immunostaining in cases which are non amplified by FISH, and that the vast majority of these false positives can be eliminated by using a normalized IHC scoring system.

Materials and Methods: A total of 9,022 breast cancer cases, representing all those submitted to PhenoPath Laboratories for FISH testing from pathology laboratories around the United States between September 2008 and May 2012, had parallel sections immunostained with the rabbit monoclonal antibody SP3 to the HER2 gene product, with localization via a polymer based detection system. Tumor was scored according to ASCO-CAP criteria, as 0, 1+, 2+ or 3+; however, scoring was tabulated in two ways. The first was an absolute HER2 score based solely on analysis of the carcinoma, and the second was a normalized HER2 score, obtained by subtracting the score of the non-neoplastic breast epithelium from that of the infiltrating cancer. FISH was performed using the Vysis PathVysion combined HER2 and CEP17 probe kit with morphometric analysis performed using a MetaSystems image analysis system that incorporated the Metafer software. A score of > 2.2 was required for classification as amplified, and <1.8 for classification as non amplified.

Results: Using the standard scoring system, negative concordance (0 or 1+ IHC, non-amplified by FISH) was obtained in 3448/3496 (98.6%) of cases, and positive concordance (3+ IHC, amplified by FISH) was obtained in 502/666 (75.3%) of cases, indicating the presence of significant numbers of falsely IHC positive cases. However, using the normalization method, the negative concordance rate remained unchanged at 3903/3960 (98.6%) but the positive concordance rate improved to 450/463 (97.2%). The absolute number of false IHC positive cases, using the normalization method, was reduced by over 90%, from 164 to 13.

Discussion: Extremely high concordance rates, with elimination of the vast majority of false IHC positive cases, can be attained in a clinical laboratory examining tissues from divergent sources, even in the absence of controlling pre-analytical variables, by employing a normalized scoring system for IHC.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-07-01.

Determining true HER2 gene status in breast cancers with polysomy by using alternative chromosome 17 reference genes: implications for anti-HER2 targeted therapy

PURPOSE

The ratio of human epidermal growth factor receptor 2 (HER2) to CEP17 by fluorescent in situ hybridization (FISH) with the centromeric probe CEP17 is used to determine HER2 gene status in breast cancer. Increases in CEP17 copy number have been interpreted as representing polysomy 17. However, pangenomic studies have demonstrated that polysomy 17 is rare. This study tests the hypothesis that the use of alternative chromosome 17 reference genes might more accurately assess true HER2 gene status.

PATIENTS AND METHODS

In all, 171 patients with breast cancer who had HER2 FISH that had increased mean CEP17 copy numbers (> 2.6) were selected for additional chromosome 17 studies that used probes for Smith-Magenis syndrome (SMS), retinoic acid receptor alpha (RARA), and tumor protein p53 (TP53) genes. A eusomic copy number exhibited in one or more of these loci was used to calculate a revised HER2-to-chromosome-17 ratio by using the eusomic gene locus as the reference.

RESULTS

Of 132 cases classified as nonamplified on the basis of their HER2:CEP17 ratios, 58 (43.9%) were scored as amplified by using alternative chromosome 17 reference gene probes, and 13 (92.9%) of 14 cases scored as equivocal were reclassified as amplified. Among the cases with mean HER2 copy number of 4 to 6, 41 (47.7%) of 86 had their HER2 gene status upgraded from nonamplified to amplified, and four (4.7%) of 86 were upgraded from equivocal to amplified.

CONCLUSION

Our results support the findings of recent pangenomic studies that true polysomy 17 is uncommon. Additional FISH studies that use probes to the SMS, RARA, and TP53 genes are an effective way to determine the true HER2 amplification status in patients with polysomy 17 and they have important potential implications for guiding HER2-targeted therapy in breast cancer.

Best practices in diagnostic immunohistochemistry: myoepithelial markers in breast pathology

CONTEXT

Numerous immunohistochemical stains have been shown to exhibit exclusive or preferential positivity in breast myoepithelial cells relative to their luminal/epithelial counterparts. These myoepithelial markers provide invaluable assistance in accurately classifying breast proliferations, especially in core biopsies. Although numerous myoepithelial markers are available, they differ in their sensitivity, specificity, and ease of interpretation, which may be attributed, to a large extent, to the variable immunoreactivity of these markers in stromal cells including myofibroblasts, vessels, luminal/epithelial cells, and tumor cells.

OBJECTIVE

To review commonly used myoepithelial markers in breast pathology and a selection of diagnostic scenarios where they may be useful.

DATA SOURCES

The information outlined in this review article is based on our experiences with routine cases and a review of English-language articles published between 1987 and 2008.

CONCLUSIONS

To demonstrate the presence or absence of myoepithelial cells, a panel-based approach of 2 or more markers is recommended. Markers that most effectively combine sensitivity, specificity, and ease of interpretation include smooth muscle myosin heavy chains, calponin, p75, p63, P-cadherin, basal cytokeratins, maspin, and CD10. These markers, however, display varying cross-reactivity patterns and variably reduced expression in the myoepithelial cells bordering in situ carcinomas. The choice of a myoepithelial marker should be dependent on a combination of factors, including published evidence on its diagnostic utility, its availability, performance characteristics that have been achieved in a given laboratory, and the specific diagnostic scenario. When its use is deemed necessary, immunohistochemistry for myoepithelial cells in breast pathology is most effective when conceptualized as supplemental, rather than central to routine morphologic interpretation.

Human epidermal growth factor receptor 2 assessment in a case-control study: comparison of fluorescence in situ hybridization and quantitative reverse transcription polymerase chain reaction performed by central laboratories

PURPOSE

The optimal method to assess human epidermal growth factor receptor 2 (HER2) status remains highly controversial. Before reporting patient HER2 results, American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines mandate that laboratories demonstrate ≥ 95% concordance to another approved laboratory or methodology. Here, we compare central laboratory HER2 assessed by fluorescence in situ hybridization (FISH) and quantitative reverse transcriptase polymerase chain reaction (RT-PCR) using Oncotype DX in lymph node-negative, chemotherapy-untreated patients from a large Kaiser Permanente case-control study.

PATIENTS AND METHODS

Breast cancer specimens from the Kaiser-Genomic Health study were examined. Central FISH assessment of HER2 amplification and polysomy 17 was conducted by PhenoPath Laboratories (ratios > 2.2, 1.8 to 2.2, and < 1.8 define HER2 positive, HER2 equivocal, and HER2 negative, respectively). HER2 expression by RT-PCR was conducted using Oncotype DX by Genomic Health (normalized expression units ≥ 11.5, 10.7 to < 11.5, and < 10.7 define HER2 positive, HER2 equivocal, and HER2 negative, respectively). Concordance analyses followed ASCO/CAP guidelines.

RESULTS

HER2 concordance by central FISH and central RT-PCR was 97% (95% CI, 96% to 99%). Twelve percent (67 of 568 patients) and 11% (60 of 568 patients) of patients were HER2 positive by RT-PCR and FISH, respectively. HER2-positive patients had increased odds of dying from breast cancer compared with HER2-negative patients. Polysomy 17 was demonstrated in 12.5% of all patients and 33% of FISH-positive patients. Nineteen of 20 FISH-positive patients with polysomy 17 were also RT-PCR HER2 positive. Although not statistically significantly different, HER2-positive/polysomy 17 patients tended to have the worst prognosis, followed by HER2-positive/eusomic, HER2-negative/polysomy 17, and HER2-negative/eusomic patients.

CONCLUSION

There is a high degree of concordance between central FISH and quantitative RT-PCR using Oncotype DX for HER2 status, and the assay warrants additional study in a trastuzumab-treated population.

Diagnostic utility of galectin-3 in thyroid cancer

Galectin-3 (Gal-3), which has received significant recent attention for its utility as a diagnostic marker for thyroid cancer, represents the most well-studied molecular candidate for thyroid cancer diagnosis. Gal-3 is a protein that binds to beta-galactosidase residues on cell surface glycoproteins and has also been identified in the cytoplasmic and nuclear compartment. This marker has been implicated in regulation of normal cellular proliferation and apoptosis, as well as malignant transformation and the metastasis of cancer cells. We here present a mechanistic review of Gal-3 and its role in cancer development and progression. Gal-3 expression studies in thyroid tissue and cytologic tumor specimens and their methodological considerations are also discussed in this article. Despite great variance in their methodology, the majority of immunohistochemical studies found that Gal-3 was differentially expressed in thyroid carcinoma compared with benign and normal thyroid specimens, suggesting that Gal-3 is a good diagnostic marker for thyroid cancer. Recent studies have also demonstrated improved methodological reliability. On the other hand, Gal-3 genomic expression studies have shown inconsistent results for diagnostic utility and are not recommended. Overall, the development of Gal-3 as a diagnostic marker for thyroid cancer represents a promising avenue for future study, and its clinical application could significantly reduce the number of diagnostic thyroid operations performed for cases of indeterminant fine needle aspiration biopsy cytology, and thus positively impact the current management of thyroid nodular disease.

Guidelines for pathologic diagnosis of malignant mesothelioma: a consensus statement from the International Mesothelioma Interest Group

CONTEXT

Malignant mesothelioma (MM) is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE

To develop practical guidelines for the pathologic diagnosis of MM.

DATA SOURCES

A pathology panel was convened at the International Mesothelioma Interest Group biennial meeting (October 2006). Pathologists with an interest in the field also contributed after the meeting.

CONCLUSIONS

There was consensus opinion regarding (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiating epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid mesothelioma, (7) use of molecular markers in the differential diagnosis of MM, (8) electron microscopy in the diagnosis of MM, and (9) some caveats and pitfalls in the diagnosis of MM. Immunohistochemical panels are integral to the diagnosis of MM, but the exact makeup of panels used is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Immunohistochemical panels should contain both positive and negative markers. The International Mesothelioma Interest Group recommends that markers have either sensitivity or specificity greater than 80% for the lesions in question. Interpretation of positivity generally should take into account the localization of the stain (eg, nuclear versus cytoplasmic) and the percentage of cells staining (>10% is suggested for cytoplasmic membranous markers). These guidelines are meant to be a practical reference for the pathologist.

Guidelines for pathologic diagnosis of malignant mesothelioma: a consensus statement from the International Mesothelioma Interest Group

CONTEXT

Malignant mesothelioma (MM) is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE

To develop practical guidelines for the pathologic diagnosis of MM.

DATA SOURCES

A pathology panel was convened at the International Mesothelioma Interest Group biennial meeting (October 2006). Pathologists with an interest in the field also contributed after the meeting.

CONCLUSIONS

There was consensus opinion regarding (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiating epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid mesothelioma, (7) use of molecular markers in the differential diagnosis of MM, (8) electron microscopy in the diagnosis of MM, and (9) some caveats and pitfalls in the diagnosis of MM. Immunohistochemical panels are integral to the diagnosis of MM, but the exact makeup of panels used is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Immunohistochemical panels should contain both positive and negative markers. The International Mesothelioma Interest Group recommends that markers have either sensitivity or specificity greater than 80% for the lesions in question. Interpretation of positivity generally should take into account the localization of the stain (eg, nuclear versus cytoplasmic) and the percentage of cells staining (>10% is suggested for cytoplasmic membranous markers). These guidelines are meant to be a practical reference for the pathologist.

Biomarker panel diagnosis of thyroid cancer: a critical review

The accurate preoperative diagnosis of thyroid cancer continues to be a significant challenge for those individuals who present with nodular thyroid disease, particularly for tumors with indeterminate cytomorphological features by fine-needle aspiration biopsy. In an effort to develop improved diagnostic tools, a number of studies have investigated the discriminatory potential of many different RNA and protein molecules. However, no individual thyroid cancer biomarker has been found with sufficient sensitivity and specificity. Therefore, research focus has shifted to panels of multiple markers with the hope of improved performance and robustness. A panel comprised of GAL3, CK19 and HBME1 is by far the most studied to date and offers some improvement over individual marker performance alone. However, relatively few marker panels have been studied and their performances and application as diagnostic tests have not been consistently reported. We present a comprehensive review of molecular marker panel studies for thyroid tumors and current issues and challenges. In the future, studies evaluating larger numbers of biomarkers in large patient cohorts are required for the development and validation of a clinically applicable test.

Human Epidermal Growth Factor Receptor 2 Overexpression As a Prognostic Factor in a Large Tissue Microarray Series of Node-Negative Breast Cancers

Purpose

Human epidermal growth factor receptor 2 gene (HER2) is associated with a poorer outcome in node-positive breast cancer, but the results are conflicting in node-negative disease. This study assessed the prognostic impact of HER2 overexpression/amplification in a large series of node-negative breast cancers.

Patients and Methods

A tissue microarray (TMA) series was constructed consisting of 4,444 invasive breast cancers diagnosed in British Columbia from 1986 to 1992. Within this series, 2,026 patients were node negative, of whom 70% did not receive adjuvant systemic therapy. The TMA series was assessed for estrogen receptor (ER) and HER2. Logistic regression modeling was used to estimate odds ratios at the 10-year follow-up.

Results

HER2 was positive in 10.2% of the node-negative cohort. In this cohort, an inferior outcome was seen in patients with HER2-positive tumors compared with HER2-negative tumors for 10-year relapse-free survival (RFS; 65.9% v 75.5%, respectively; P = .01), distant RFS (71.2% v 81.8%, respectively; P = .004), and breast cancer–specific survival (BCSS; 75.5% v 86.3%, respectively; P = .001). A trend for a worse overall survival was also seen (P = .06). HER2 was an independent poor prognostic factor for RFS and BCSS at 10 years, with odds ratios of 1.71 (P = .01) and 2.03 (P = .003), respectively. The number of HER2-positive tumors that were ≤ 1 cm was small, but there was a trend for a worse outcome in T1b tumors.

Conclusion

HER2 overexpression/amplification is correlated with a poorer outcome in node-negative breast cancer. Larger studies are needed to more clearly define the prognostic impact of HER2 in tumors ≤ 1 cm, particularly within the separate hormone receptor subgroups.

High concordance between immunohistochemistry and fluorescence in situ hybridization testing for HER2 status in breast cancer requires a normalized IHC scoring system

The American Society of Clinical Oncologists and College of American Pathologists have recently released new guidelines for laboratory testing of HER2 status in breast cancer, which require high levels (95%) of concordance between immunohistochemistry positive (3+) and fluorescence in situ hybridization-amplified cases, and between immunohistochemistry negative (0/1+) and fluorescence in situ hybridization-nonamplified cases; these required levels of concordance are significantly higher than those found in most published studies. We tested the hypothesis that a modification of the HER2 immunohistochemistry scoring system could significantly improve immunohistochemistry and fluorescence in situ hybridization concordance. A total of 6604 breast cancer specimens were evaluated for HER2 status by both immunohistochemistry and fluorescence in situ hybridization using standard methodologies. Results were compared when the standard immunohistochemistry scoring system was replaced by a normalized scoring system in which the HER2 score was derived by subtracting the score on the non-neoplastic breast epithelium from that on the tumor cells. Among the 6604 tumors, using a non-normalized immunohistochemistry scoring system, 267/872 (30.6%) of the immunohistochemistry 3+ cases proved to be fluorescence in situ hybridization nonamplified, whereas using the normalized scoring system only 30/562 (5.3%) of immunohistochemistry 3+ cases proved to be 'false positive'. The concordance rate between immunohistochemistry 3+ and fluorescence in situ hybridization-amplified cases using the normalized scoring method was 94.7%, whereas the concordance using the non-normalized method was only 69.4%. Extremely high concordance between immunohistochemistry and fluorescence in situ hybridization assessment of HER2 status in breast cancer is achievable, but to attain this high level of concordance, modification of the FDA-approved immunohistochemistry scoring system is required.

Antibody-mediated blockade of integrin alpha v beta 6 inhibits tumor progression in vivo by a transforming growth factor-beta-regulated mechanism

The alpha(v)beta(6) integrin is up-regulated on epithelial malignancies and has been implicated in various aspects of cancer progression. Immunohistochemical analysis of alpha(v)beta(6) expression in 10 human tumor types showed increased expression relative to normal tissues. Squamous carcinomas of the cervix, skin, esophagus, and head and neck exhibited the highest frequency of expression, with positive immunostaining in 92% (n = 46), 84% (n = 49), 68% (n = 56), and 64% (n = 100) of cases, respectively. We studied the role of alpha(v)beta(6) in Detroit 562 human pharyngeal carcinoma cells in vitro and in vivo. Prominent alpha(v)beta(6) expression was detected on tumor xenografts at the tumor-stroma interface resembling the expression on human head and neck carcinomas. Nonetheless, coculturing cells in vitro with matrix proteins did not up-regulate alpha(v)beta(6) expression. Detroit 562 cells showed alpha(v)beta(6)-dependent adhesion and activation of transforming growth factor-beta (TGF-beta) that was inhibited >90% with an alpha(v)beta(6) blocking antibody, 6.3G9. Although both recombinant soluble TGF-beta receptor type-II (rsTGF-beta RII-Fc) and 6.3G9 inhibited TGF-beta-mediated Smad2/3 phosphorylation in vitro, there was no effect on proliferation. Conversely, in vivo, 6.3G9 and rsTGF-beta RII-Fc inhibited xenograft tumor growth by 50% (n = 10, P < 0.05) and >90% (n = 10, P < 0.001), respectively, suggesting a role for the microenvironment in this response. However, stromal collagen and smooth muscle actin content in xenograft sections were unchanged with treatments. Although further studies are required to consolidate in vitro and in vivo results and define the mechanisms of tumor inhibition by alpha(v)beta(6) antibodies, our findings support a role for alpha(v)beta(6) in human cancer and underscore the therapeutic potential of function blocking alpha(v)beta(6) antibodies.