HER2 in situ hybridization in breast cancer: clinical implications of polysomy 17 and genetic heterogeneity.

Trastuzumab-containing therapy is a standard of care for patients with HER2+ breast cancer. HER2 status is routinely assigned using in situ hybridization to assess HER2 gene amplification, but interpretation of in situ hybridization results may be challenging in tumors with chromosome 17 polysomy or intratumoral genetic heterogeneity. Apparent chromosome 17 polysomy, defined by increased chromosome enumeration probe 17 (CEP17) signal number, is a common genetic aberration in breast cancer and represents an alternative mechanism for increasing HER2 copy number. Some studies have linked elevated CEP17 count ('polysomy') with adverse clinicopathologic features and HER2 overexpression, although there are numerous discrepancies in the literature. There is evidence that elevated CEP17 ('polysomy') count might account for trastuzumab response in tumors with normal HER2:CEP17 ratios. Nonetheless, recent studies establish that apparent 'polysomy' (CEP17 increase) is usually related to focal pericentromeric gains rather than true polysomy. Assigning HER2 status may also be complex where multiple cell subclones with distinct HER2 amplification characteristics coexist within the same tumor. Such genetic heterogeneity affects up to 40% of breast cancers when assessed according to a College of American Pathologists guideline, although other definitions have been proposed. Recent data have associated heterogeneity with unfavorable clinicopathologic variables and poor prognosis. Genetically heterogeneous tumors harboring HER2-amplified subclones have the potential to benefit from trastuzumab, but this has yet to be evaluated in clinical studies. In this review, we discuss the implications of apparent polysomy 17 and genetic heterogeneity for assigning HER2 status in clinical practice. Among our recommendations, we support the use of mean HER2 copy number rather than HER2:CEP17 ratio to define HER2 positivity in cases where coamplification of the centromere might mask HER2 amplification. We also highlight a need to harmonize in situ hybridization scoring methodology to support accurate HER2 status determination, particularly where there is evidence of heterogeneity.

Assessing HER2 amplification in breast cancer: findings from the Australian In Situ Hybridization Program.

In August 2006, the Australian government approved subsidized trastuzumab therapy for human epidermal growth factor receptor 2 (HER2)-positive early breast cancer, and it was mandated that HER2 testing should be performed using in situ hybridization (ISH) rather than immunohistochemistry (IHC). Here we review results of the first regulated, nationwide program to provide HER2 ISH testing for all newly diagnosed breast cancer patients, with a particular emphasis on cases where IHC and ISH results were discordant. Data from all laboratories participating in the program were collated. Cases with an equivocal ISH test result [by chromogenic ISH (CISH) or silver ISH (SISH)] were tested centrally by fluorescence ISH. Most laboratories also performed HER2 IHC, and 200 cases with discordant IHC and ISH results were selected for further analysis in a central laboratory. A total of 26 laboratories were involved and 53,402 tests were reported. Over a 4-year period the HER2 positivity rate decreased for primary cancers from 23.8 to 14.6 %, but remained relatively constant for samples from metastases. Average ISH reporting times were <5 days for all yearly reporting periods. Test-repeat rates decreased for CISH (8.9-3.6 %) and SISH (13.7-8.4 %). Only 12 of 196 cases remained discordant after retesting in a central laboratory. These findings demonstrate the successful implementation of a regulated, national program that continues to collect data on HER2 status. The results also highlight the differences in IHC interpretation between local laboratories and a central, more experienced, laboratory. This model could be used to establish future biomarker-testing programs in other countries.

HER2 testing in gastric cancer: a practical approach.

Trastuzumab in combination with capecitabine or 5-fluorouracil and cisplatin is approved by the European Medicines Agency for the treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive (immunohistochemistry 3+ or immunohistochemistry 2+/fluorescence in situ hybridization-positive or immunohistochemistry 2+/silver in situ hybridization-positive) metastatic adenocarcinoma of the stomach or gastro-esophageal junction. Approvals are underway in other countries, with recent approvals granted in the United States and Japan. Experience and data from trastuzumab use in breast cancer have highlighted the importance of quality HER2 testing and scoring to ensure accurate identification of patients eligible for treatment. HER2 testing in gastric cancer differs from testing in breast cancer due to inherent differences in tumor biology; gastric cancer more frequently shows HER2 heterogeneity (focal staining) and incomplete membrane staining. Consequently, gastric cancer-specific HER2 testing protocols have been developed and standardized and it is imperative that these recommendations be adhered to. Given the predictive value of HER2 protein levels with response in the trastuzumab for GAstric cancer study (ToGA), immunohistochemistry should be the initial testing methodology and fluorescence in situ hybridization or silver in situ hybridization should be used to retest immunohistochemistry 2+ samples. Wherever possible, bright-field methodologies should be used as these are considered to be superior to fluorescent methodologies at identifying heterogeneous staining. Specific training is required before embarking on HER2 testing in gastric cancer, irrespective of the experience of HER2 testing in breast cancer. This paper provides the most up-to-date practical guidance on HER2 testing and scoring in patients with gastric and gastro-esophageal junction cancer, as agreed by a panel of expert pathologists with extensive experience of HER2 testing particularly reflecting the European Medicines Agency-approved indication. It is anticipated that these recommendations should ensure accurate and consistent HER2 testing, which will allow appropriate selection of patients eligible for treatment with trastuzumab.

HER2 discordance between primary breast cancer and its paired metastasis: tumor biology or test artefact? Insights through meta-analysis.

The proto-oncogene, HER2, has prognostic and predictive relevance in invasive breast cancer (IBC). HER2 testing of primary IBC guides treatment selection and is assumed to reflect HER2 status of associated metastases, although HER2 discordance between IBC and metastasis has been reported. Systematic review and meta-analysis of HER2 status in IBC and its paired loco-regional or distant metastasis were done. Quality appraisal considered whether (within-subject) testing conditions were maintained for paired primary and metastasis. Random effects logistic regression models were used to estimate pooled within-subject HER2 discordant proportions and to examine study-level covariates, including tumor-related and testing-related variables, potentially associated with HER2 discordance differences across (between) studies. Modelled paired HER2 data for primary and metastatic cancer (2520 subjects, 26 studies) showed a pooled HER2 discordance of 5.5% (3.6-8.5%). Sensitivity analysis, excluding the only study not maintaining same conditions for paired testing, gave a pooled estimate of 5.2% (3.5-7.8%). Pooled discordant proportion was not associated with differences between studies in test type, test scoring or interpretation criteria, subjects' median age, study time-frame, or HER2 positivity in primary cancer (all P > 0.05). However, type of metastasis was significantly associated with estimated HER2 discordance (P = 0.0017): studies of primary tumor paired with distant metastases had higher discordance [11.5% (6.9-18.6%)] than studies of primary paired with lymph node metastases only [4.1% (2.4-7.2%)], or those paired with nodal or various metastases [3.3% (2.0-5.6%)]; P < 0.01. HER2 discordant proportion was higher where paired metastases were metachronous relative to synchronous to primary IBC (P = 0.0024). Sensitivity analysis provided weak evidence (P = 0.074) that discordance in the direction of change from HER2-negative primary cancer to HER2-positive paired metastasis was more likely than the reverse. Study-level meta-analysis suggests factors associated with the type of metastasis as underlying mechanisms for observed HER2 discordance between primary IBC and paired metastasis. Test-related factors did not account for differences across studies in the HER2 discordant proportion.

HER3 and downstream pathways are involved in colonization of brain metastases from breast cancer.

INTRODUCTION: Metastases to the brain from breast cancer have a high mortality, and basal-like breast cancers have a propensity for brain metastases. However, the mechanisms that allow cells to colonize the brain are unclear. METHODS: We used morphology, immunohistochemistry, gene expression and somatic mutation profiling to analyze 39 matched pairs of primary breast cancers and brain metastases, 22 unmatched brain metastases of breast cancer, 11 non-breast brain metastases and 6 autopsy cases of patients with breast cancer metastases to multiple sites, including the brain. RESULTS: Most brain metastases were triple negative and basal-like. The brain metastases over-expressed one or more members of the HER family and in particular HER3 was significantly over-expressed relative to matched primary tumors. Brain metastases from breast and other primary sites, and metastases to multiple organs in the autopsied cases, also contained somatic mutations in EGFR, HRAS, KRAS, NRAS or PIK3CA. This paralleled the frequent activation of AKT and MAPK pathways. In particular, activation of the MAPK pathway was increased in the brain metastases compared to the primary tumors. CONCLUSIONS: Deregulated HER family receptors, particularly HER3, and their downstream pathways are implicated in colonization of brain metastasis. The need for HER family receptors to dimerize for activation suggests that tumors may be susceptible to combinations of anti-HER family inhibitors, and may even be effective in the absence of HER2 amplification (that is, in triple negative/basal cancers). However, the presence of activating mutations in PIK3CA, HRAS, KRAS and NRAS suggests the necessity for also specifically targeting downstream molecules.

Breast core needle biopsy: issues and controversies.

Core needle biopsy (CNB) is increasingly being used in the investigation of breast disease whether this is asymptomatic and suspected after screening mammography, or presents symptomatically in the patient. In most cases, the result of the procedure provides a definitive diagnosis or at least provides information that is used to plan the further management of the patient. There are, however, a number of unresolved issues with the use of CNB; for example, with regard to the amount of information that can be reliably derived from CNB or with regard to the management of the patient after some CNB diagnoses. Oestrogen and progesterone receptors and HER2 are reported on both core biopsies and excision specimens, but there continues to be debate over which represents the more appropriate specimen type on which to perform these tests. There are a number of possible diagnoses after CNB for which the management is not straightforward and around which there may be controversy, or just a lack of sufficient evidence to support a definite management plan. These 'lesions of uncertain malignant potential' include papillary lesions, fibroepithelial lesions with cellular stroma, mucocoele-like lesions and radial scars. Currently, these are removed surgically but there may be an argument for more conservative management including vacuum-assisted core excision in some cases.

ASCO/CAP 2018 breast cancer HER2 testing guidelines: summary of pertinent recommendations for practice in Australia.

The latest update to the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2 testing in breast cancer guidelines was published in 2018. A multidisciplinary expert committee, convened under the auspices of the Royal College of Pathologists of Australasia (RCPA) Structured Pathology Reporting framework, evaluated the implications of these guidelines for clinical practice in Australia. Following feedback from professional bodies, including the RCPA and CanSAC, peer review was invited. The final document prepared by the authors, endorsed by the Expert Committee RCPA Structured Pathology Reporting of Breast Cancer and by CanSAC, is published herein.

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update.

PURPOSE.­: To update key recommendations of the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) human epidermal growth factor receptor 2 (HER2) testing in breast cancer guideline. METHODS.­: Based on the signals approach, an Expert Panel reviewed published literature and research survey results on the observed frequency of less common in situ hybridization (ISH) patterns to update the recommendations. RECOMMENDATIONS.­: Two recommendations addressed via correspondence in 2015 are included. First, immunohistochemistry (IHC) 2+ is defined as invasive breast cancer with weak to moderate complete membrane staining observed in >10% of tumor cells. Second, if the initial HER2 test result in a core needle biopsy specimen of a primary breast cancer is negative, a new HER2 test may (not "must") be ordered on the excision specimen based on specific clinical criteria. The HER2 testing algorithm for breast cancer is updated to address the recommended workup for less common clinical scenarios (approximately 5% of cases) observed when using a dual-probe ISH assay. These scenarios are described as ISH group 2 ( HER2/chromosome enumeration probe 17 [CEP17] ratio ≥2.0; average HER2 copy number <4.0 signals per cell), ISH group 3 ( HER2/CEP17 ratio <2.0; average HER2 copy number ≥6.0 signals per cell), and ISH group 4 ( HER2/CEP17 ratio <2.0; average HER2 copy number ≥4.0 and <6.0 signals per cell). The diagnostic approach includes more rigorous interpretation criteria for ISH and requires concomitant IHC review for dual-probe ISH groups 2 to 4 to arrive at the most accurate HER2 status designation (positive or negative) based on combined interpretation of the ISH and IHC assays. The Expert Panel recommends that laboratories using single-probe ISH assays include concomitant IHC review as part of the interpretation of all single-probe ISH assay results.

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update.

Purpose To update key recommendations of the American Society of Clinical Oncology/College of American Pathologists human epidermal growth factor receptor 2 (HER2) testing in breast cancer guideline. Methods Based on the signals approach, an Expert Panel reviewed published literature and research survey results on the observed frequency of less common in situ hybridization (ISH) patterns to update the recommendations. Recommendations Two recommendations addressed via correspondence in 2015 are included. First, immunohistochemistry (IHC) 2+ is defined as invasive breast cancer with weak to moderate complete membrane staining observed in > 10% of tumor cells. Second, if the initial HER2 test result in a core needle biopsy specimen of a primary breast cancer is negative, a new HER2 test may (not "must") be ordered on the excision specimen based on specific clinical criteria. The HER2 testing algorithm for breast cancer is updated to address the recommended work-up for less common clinical scenarios (approximately 5% of cases) observed when using a dual-probe ISH assay. These scenarios are described as ISH group 2 ( HER2/chromosome enumeration probe 17 [CEP17] ratio ≥ 2.0; average HER2 copy number < 4.0 signals per cell), ISH group 3 ( HER2/CEP17 ratio < 2.0; average HER2 copy number ≥ 6.0 signals per cell), and ISH group 4 ( HER2/CEP17 ratio < 2.0; average HER2 copy number ≥ 4.0 and < 6.0 signals per cell). The diagnostic approach includes more rigorous interpretation criteria for ISH and requires concomitant IHC review for dual-probe ISH groups 2 to 4 to arrive at the most accurate HER2 status designation (positive or negative) based on combined interpretation of the ISH and IHC assays. The Expert Panel recommends that laboratories using single-probe ISH assays include concomitant IHC review as part of the interpretation of all single-probe ISH assay results. Find additional information at www.asco.org/breast-cancer-guidelines .

Chromogenic in situ hybridisation for the assessment of HER2 status in breast cancer: an international validation ring study.

INTRODUCTION: Before any new methodology can be introduced into the routine diagnostic setting it must be technically validated against the established standards. To this end, a ring study involving five international pathology laboratories was initiated to validate chromogenic in situ hybridisation (CISH) against fluorescence in situ hybridisation (FISH) and immunohistochemistry (IHC) as a test for assessing human epidermal growth factor receptor 2 (HER2) status in breast cancer. METHODS: Each laboratory performed CISH, FISH and IHC on its own samples. Unstained sections from each case were also sent to another participating laboratory for blinded retesting by CISH ('outside CISH'). RESULTS: A total of 211 invasive breast carcinoma cases were tested. In 76 cases with high amplification (HER2/CEP17 ratio >4.0) by FISH, 73 cases (96%) scored positive (scores >or= 6) by 'outside CISH'. For FISH-negative cases (HER2/CEP17 ratio <2.0), 94 of 100 cases (94%) had CISH scores indicating no amplification (score or= 6. CISH intra-laboratory concordance with IHC was 92% for IHC-negative cases (IHC 0/1+) and 91% for IHC 3+ cases. Among IHC 2+ cases, CISH was 100% concordant with samples showing high amplification by FISH, and 94% concordant with FISH-negative samples. CONCLUSION: These results show that CISH inter- and intra-laboratory concordance to FISH and IHC is very high, even in equivocal IHC 2+ cases. Therefore, we conclude that CISH is a methodology that is a viable alternative to FISH in the HER2 testing algorithm.

HER2 testing in advanced gastric and gastro-oesophageal cancer: analysis of an Australia-wide testing program.

This Australian human epidermal growth factor receptor 2 (HER2) testing program aimed to analyse >800 cases tested in a coordinated setting to further evaluate the criteria to establish HER2 status in advanced gastric and gastro-oesophageal junction (GOJ) cancer. Heterogeneity, and minimum number of biopsy fragments for reliable HER2 assessment were also examined in a subset of samples. Five laboratories tested 891 samples referred to determine HER2 status for potential anti-HER2 treatment. Cancer site, specimen type (endoscopic biopsy/resection/metastases), immunohistochemistry (IHC) score, HER2 gene and CEP17 copy number (CN) and HER2:CEP17 ratios were recorded. Samples were derived from stomach (53.1%), GOJ (28.2%) or metastases (18.5%). IHC for HER2 and dual probe HER2:CEP17 in situ hybridisation (ISH) were performed in parallel. A stringent definition (SD) of HER2 positivity was used (IHC2+/3+ plus CN>6 and ratio>2) and compared with other published criteria. HER2 positive rate was 13.9% (114/820) by SD, and 12.9-16.0% using other definitions. There was higher concordance between IHC and HER2 CN by ISH than with ratio. The HER2 positive rate was significantly higher in GOJ samples than others (p = 0.03) and in endoscopic biopsies than resections (p = 0.047). In a subset of 98 positive cases, 39 (39.8%) showed heterogeneity, and in 282 endoscopic biopsies positivity rate plateaued at five tumour fragments, suggesting this is the minimum number of biopsies that should be examined.

Human epidermal growth factor receptor 2 status of gastric cancer patients in Asia: results from a large, multicountry study.

AIM: Current estimates of the human epidermal growth factor receptor 2 (HER2)-positivity rate in gastric cancer vary widely in the literature, and there are limited data from countries in Asia. The primary aim of this study was to conduct a clinical audit of laboratories across seven countries in Asia to determine the incidence of HER2-positive gastric cancer in this region. METHODS: Pathologists were asked to collect data on patient gender, age, cancer site, specimen type, tumor spread, type and grade, HER2 test results, including protein and/or gene copy enumeration, and final HER2 status on consecutive gastric cancer cases tested for HER2 in their laboratory over a 2-year period. RESULTS: HER2 results from 5,301 gastric cancers were submitted by 50 laboratories. The overall HER2-positivity rate was 9.7% which, after the exclusion of China, increased to 18.1%. The rate between countries ranged from 0% to 23.1%, and from 0% to 50.0% between laboratories. An equivocal HER2 result was recorded in 19.5% of cases. CONCLUSION: Despite the lack of centralized testing to confirm the accuracy of HER2 diagnoses, the incidence of HER2-positive gastric cancer observed here was comparable to that reported in the literature. Nevertheless, rates were highly variable between countries and laboratories, which suggests a lack of HER2 testing expertise in gastric cancer. Given that the mortality rates for gastric cancer in Eastern Asia are the highest in the world, efforts should focus on improving HER2 testing expertise in the region so that patients receive the appropriate treatment early in their disease.

Intraoperative imprint cytology of sentinel lymph nodes in breast cancer: initial experience and lessons learnt in establishing a new practice.

AIMS: The initial 18 months experience of performing intraoperative imprint cytology for patients with breast cancer undergoing sentinel lymph node biopsy is described for a single institution. The learning process is compared with published results from institutions with many years of experience in order to assess progress in reaching those ideal results, and the methodology used by these institutions is reviewed. METHODS: A retrospective review was undertaken of the intraoperative imprint cytology results from 103 patients with breast cancer (yielding a total of 170 lymph nodes) who underwent imprint cytology of their sentinel lymph node. The intraoperative imprint cytology results were compared with the final histopathological results. Details regarding the primary tumour characteristics and metastatic deposit size were recorded. RESULTS: The sensitivity for imprint cytology was 31.1%, with a specificity of 100% and overall accuracy of 77.8%. The sensitivity for detecting macrometastases (>2 mm diameter) was 61.9% and the sensitivity for micrometastases (<2 mm diameter) and including isolated tumour cells was 4.2%. CONCLUSIONS: The differences in sensitivity in comparison with many studies in the literature are multifactorial, and include technical aspects, such as the methodology used in the final histopathological and intraoperative evaluation of the sentinel lymph nodes, interpretative difficulties, and much lower case numbers. Furthermore, these numbers represent early experience and methods to improve sensitivity and overall accuracy are detailed in this paper.

Chromogenic in situ hybridisation testing for HER2 gene amplification in breast cancer produces highly reproducible results concordant with fluorescence in situ hybridisation and immunohistochemistry.

AIMS: The objective of this study was to evaluate the accuracy, ease of use and reproducibility of chromogenic in situ hybridisation (CISH) for HER2 testing by studying its inter-laboratory concordance in five Australian pathology laboratories. METHODS: The HER2 status of 49 breast cancers was determined by CISH twice in two different laboratories. Each sample had previously been tested by immunohistochemistry (IHC; 2+ and 3+ cases selected) and fluorescence in situ hybridisation (FISH). Participating laboratories were blinded to these test results. Oestrogen receptor (ER) status was also evaluated for each cancer. RESULTS: High correlation was observed between FISH and CISH results. No cases showing high gene amplification by FISH were scored as non-amplified by CISH (kappa coefficient = 1). High correlation was observed between IHC and CISH, all IHC 3+ samples showing amplification by CISH. Inter-laboratory CISH concordance was also good (kappa coefficient = 0.67). Fifty-six per cent of HER2-amplified samples tested ER positive, while 42% of ER-positive cases showed HER2 gene amplification, confirming that HER2 testing should not be confined to ER-negative breast cancers. CONCLUSIONS: These findings demonstrate that CISH is a robust test to assess HER2 status in breast cancer and therefore is an important addition to the HER2 testing algorithm.

Mycobacterium tuberculosis presenting as chronic red eye.

PURPOSE: To report a case of tuberculosis of the conjunctiva. METHODS: Case report with pathologic correlation. A 17-year-old man who had relocated to Australia from Liberia presented with chronic unilateral conjunctivitis. RESULTS: The diagnosis was not initially evident, despite 2 separate biopsy specimens, conjunctival cultures, and polymerase chain reaction testing. Definitive diagnosis was made after repeated histologic examination. Antituberculous treatment resulted in prompt resolution of all ocular signs. CONCLUSION: Tuberculous conjunctivitis is now a very rare condition in the developed world. Definitive diagnosis requires the identification of Mycobacterium tuberculosis organisms in conjunctival biopsy specimens-either through microscopic detection of acid-fast bacilli or more sensitive culture techniques.

Human epidermal growth factor receptor 2 status of breast cancer patients in Asia: Results from a large, multicountry study.

AIM: Current estimates of the human epidermal growth factor receptor 2 (HER2)-positivity rate in breast cancer are largely based on studies from the United States, Europe and Australia, and might not reflect the rate among breast cancer patients in Asia. The primary aim of this study was to conduct a clinical audit of laboratories across eight countries in Asia to determine the incidence of HER2-positive breast cancer in this region. METHODS: Pathology laboratories submitted data on breast cancers consecutively tested for HER2 over a two-year period. The proportion of HER2-positive, -equivocal and -negative tumors was determined for each country and overall. HER2-positivity rate by age and histological grade was also determined. RESULTS: HER2 results from 30 179 breast cancers were submitted by 96 laboratories. The overall HER2-positivity rate was 23.5%; the rate between countries ranged from 19.7% to 44.2%, and from 4.4% to 51.6% between laboratories. An equivocal HER2 result was recorded in 18.2% of cases. Discrepancies between laboratories suggest that testing expertise contributes to variations seen in HER2 status across laboratories, as well as the generally higher rate of HER2-positivity that was recorded. CONCLUSION: In this study, the incidence of HER2-positive breast cancer diagnosed in Asian women was higher than published studies on women from Western countries. In addition, the study found that women in Asian countries presented with breast cancer at an earlier age, with a higher histological grade. This study serves to highlight the challenges with HER2 testing and data collection in a large multicenter Asian cohort.

Determining HER2 (ERBB2) amplification status in women with breast cancer: final results from the Australian in situ hybridisation program.

Appropriate and accurate determination of HER2 status in women with breast cancer is critical for stratifying anti-HER2 therapies, and for access to subsidised treatment in the Australian setting. We conducted a regulated, nationwide program providing HER2 in situ hybridisation (ISH) testing for patients with newly diagnosed breast cancer. Cases with equivocal or non-diagnostic ISH test results at the local laboratory were sent to a high volume central testing laboratory for analysis using fluorescence ISH (FISH). We tested 78,408 early breast cancers and 3469 metastatic cancers using ISH. Of these, 12,405 early breast cancers (15.8%) and 798 metastatic cancers (23.0%) were HER2 positive. During the testing period, the proportion of core biopsy samples increased, the number of repeat tests remained stable and testing turnaround time declined. Discordant 3+ IHC, ISH negative results dropped from 20% to 13% in early breast cancers and from 35% to 8% among metastatic breast cancers. Following central laboratory FISH testing only 87 samples remained non-diagnostic (1.9% of FISH-tested samples, 0.1% of the whole cohort), most being decalcified specimens. This is a successful story of a cohesive service determining HER2 status in women with breast cancer in a 'real-world' setting.

Making sense of breast pathology.

An understanding of breast pathology is essential when caring for women with breast disease. Part five of this series discusses the spectrum of common benign and malignant conditions including the distinction between invasive and noninvasive breast cancer. It also aims to increase the general practitioner's confidence in understanding breast pathology reports, arranging appropriate referral for patients, and educating women about their disease.

Intraoperative sentinel lymph node assessment in breast cancer: a comparison of rapid diagnostic method based on CK19 mRNA expression and imprint cytology.

BACKGROUND: Sentinel lymph node biopsy in breast cancer is a routine technique for staging the axilla. The two most common methods of intraoperative histopathological assessment, imprint cytology and frozen section, are hampered by poor sensitivity and lack standardized methodology. The one-step nuclei acid amplification (OSNA) assay is a rapid quantification of cytokeratin 19 mRNA. This prospective study compared an existing intraoperative imprint cytology protocol with the OSNA system. METHODS: Of the 110 prospectively recruited patients, 98 met the inclusion criteria with a total of 170 lymph nodes. Intraoperative sentinel nodes were serially sectioned and imprints made of each cut surface for cytological assessment. Alternate slices were submitted for OSNA while the remaining slices were for final histopathological evaluation with six hematoxylin and eosin levels and one AE1/AE3 immunoperoxidase stain of each slice. RESULTS: On histopathological analysis, 24.5% of patients (16.5% of nodes) had sentinel node metastases and 3.1% (2.4%) had isolated tumour cells. With isolated tumour cells cases taken as negative, the sensitivity of imprint cytology and OSNA compared with histopathology were 66.7% on patient basis (71.4% on per-node basis) and 95.8% (89.3%), respectively. One of 22 patients with macrometastases and two of three micrometastases were designated negative while five false-positive nodes were identified with OSNA, likely due to tissue allocation bias. CONCLUSION: The OSNA assay is highly sensitive in comparison with imprint cytology and may be used effectively in the intraoperative setting. Clinical follow-up studies are warranted to further assess its use in routine practice.

Human epidermal growth factor receptor 2 testing in gastric cancer: recommendations of an Asia-Pacific task force.

Human epidermal growth factor receptor 2 (HER2) testing in gastric and gastroesophageal junction cancer is an evolving area in clinical practice that has particular relevance to Asia-Pacific countries, which face a high incidence of these diseases. A growing body of evidence demonstrates that HER2-targeted therapy improves survival for patients with HER2-positive advanced disease, and drives the need for high-quality testing procedures to identify patients who will respond to treatment. However, various factors challenge day-to-day testing of gastric specimens in these countries, to a degree greater than that observed for breast specimens. Recommendations for HER2 testing of gastric cancer specimens were published as a result of the Trastuzumab for Gastric Cancer (ToGA) trial. The guidelines proposed in this manuscript build on these recommendations and emphasize local testing environments, particularly in Asia-Pacific countries. A multidisciplinary task force comprising experts from Asia-Pacific who actively work and provide education in the area was convened to assess the applicability of existing recommendations in the Asia-Pacific region. The resulting recommendations reported here highlight and clarify aspects of testing that are of particular relevance to the region, and notably emphasize multidisciplinary collaborations to optimize HER2 testing quality.