Microinvasion is the smallest morphologically identifiable stage of invasion. Its presence and distinction from in situ carcinoma may have therapeutic implications, and clinical staging also requires the recognition of this phenomenon. Microinvasion is established on the basis of several morphological criteria, which may be difficult and not perfectly reproducible among pathologists. The aim of this study was to assess the consistency of diagnosing microinvasion in the breast on traditional haematoxylin and eosin (HE) stained slides and to evaluate whether immunohistochemistry (IHC) for myoepithelial markers could improve this. Digital images were generated from representative areas of 50 cases stained with HE and IHC for myoepithelial markers. Cases were specifically selected from the spectrum of in situ to microinvasive cancers. Twenty-eight dedicated breast pathologists assessed these cases at different magnifications through a web-based platform in two rounds: first HE only and after a washout period by both HE and IHC. Consistency in the recognition of microinvasion significantly improved with the use of IHC. Concordance rates increased from 0.85 to 0.96, kappa from 0.5 to 0.85, the number of cases with 100% agreement rose from 9/50 to 25/50 with IHC and the certainty of diagnosis also increased. The use of IHC markedly improves the consistency of identifying microinvasion. This corroborates previous recommendations to use IHC for myoepithelial markers to clarify cases where uncertainty exists about the presence of microinvasion. Microinvasive carcinoma is a rare entity, and seeking a second opinion may avoid overdiagnosis.

606 Background: Genomic grade index (GGI) is a 97-gene signature which improves accuracy and prognostic value of histological grading (HG) in invasive breast carcinoma (IBC). GGI is particularly useful in segregating HG2 tumors into low or high Genomic Grade (GG1 and GG3). We aimed at prospectively evaluating the feasibility to implement GGI in routine practice with the primary objective of obtaining GGI in at least 80% of fresh tumor samples collected at surgery. Secondary objectives include GGI classification performance and impact on treatment recommendations.METHODSEligible patients were pT1pT2 or operable pT3, N0-3 IBC. Fresh surgical samples with a H&E slide representative of the tumor specimen were sent at room temperature in the MapQuantKit for centralized analysis. Genomic profiles (Affymetrix U133 Plus 2.0) were determined for samples containing ≥ 30% invasive tumor cells and GGI calculated using the Ipsogen MapQuantDx protocol, which defines tumors as GG1 or GG3.RESULTSBetween Jan and Dec 2010, 173 pts were recruited in eight centers in Belgium and 151 were eligible (21 pts N >3, 1 pt no IBC). MapQuant test was performed in 138 cases (excluding 8 tumors too small for sampling, 3 samples forgotten, 2 with no H&E slide) and GGI was obtained in 78% of cases (n=108). Reasons for failures were: 15 samples with <30% of invasive tumor cells (11%), 14 insufficient RNA quality (10%) and 1 failed hybridization (<1%). For tumors with an available representative sample (≥ 30% inv. tumor cells) (n=123) the success rate was 88%. Of 138 tumor samples collected, 77% were N0, 81% were ER+, 10% HER2+ and 9% triple negative; median tumor size was 17mm (range 6-55). The HG1, HG2 and HG3 frequencies were 24%, 48% and 28% resp. Concordance between HG1/HG3 Histologic and GG1/GG3 Genomic grading was 90%. GGI reclassified 67% of the 52 HG2 tumors as GG1 (51%) or GG3 (49%) leading to a total of 34% GG1 (n=37), 44% GG3 (n=47) and 22% undetermined (UD) (n=24).CONCLUSIONSGenomic Grade is feasible in routine clinical practice with a success rate of 88% when a representative tumor sample is provided. The impact of GGI on treatment decision will be presented at the meeting.

PURPOSE Application of current nodal status classification is complicated in lobular breast carcinoma metastases. The aim of this study was to define the optimal interpretation of the pTNM classification in sentinel node (SN) -positive patients to select patients with limited or with a high risk of non-SN involvement. PATIENTS AND METHODS SN metastases of 392 patients with lobular breast carcinoma were reclassified according to interpretations of the European Working Group for Breast Screening Pathology (EWGBSP) and guidelines by Turner et al, and the predictive power for non-SN involvement was assessed. Results Reclassification according to definitions of EWGBSP and Turner et al resulted in different pN classification in 73 patients (19%). The rate of non-SN involvement in the 40 patients with isolated tumor cells according to Turner et al and with micrometastases according to EWGBSP was 20%, which is comparable to the established rate for micrometastases. The rate of non-SN involvement in the 29 patients with micrometastases according to Turner et al and with macrometastases according to EWGBSP was 48%, which is comparable to the established rate for macrometastases. Therefore, the EWGBSP method to classify SN tumor load better reflected the risk of non-SN involvement than the Turner et al system. CONCLUSION Compared with the guidelines by Turner et al, the EWGBSP definitions better reflect SN metastatic tumor load and allow better differentiation between patients with lobular breast carcinoma who have a limited or a high risk of non-SN metastases. Therefore, we suggest using the EWGBSP definitions in these patients to select high-risk patients who may benefit from additional local and/or systemic therapy.

Isolated tumour cells and micrometastases represent two different staging categories and are often dealt with differently when identified in sentinel lymph nodes of breast cancer patients. The reproducibility of these categories was found to be suboptimal in several studies. The new edition of the TNM (Tumour Node Metastasis) is expected to improve the reproducibility of these categories. Fifty cases of possible low-volume nodal involvement were represented by one to four digital images and were analysed by members of the European Working Group for Breast Screening Pathology (EWGBSP). The kappa value for interobserver agreement of the pN (TNM) staging categories and of the isolated tumour cells category were 0.55 and 0.56 reflecting moderate reproducibility, and the kappa of the micrometastatic category (0.62) reflected substantial reproducibility. This is an improvement over the results gained on the basis of the previous edition of the TNM. Maximal adherence to the category definitions supplemented by explanatory texts in the staging manual should result in more homogeneous nodal staging of breast cancer.

Click to increase image sizeClick to decrease image sizeKey Words: Breast cancersentinel lymphnodemicrometastasecancer staging Additional informationNotes on contributorsT. DefechereuxT. Defechereux Service de Chirurgie des Glandes Endocrines, B-35 Centre Hospitalier Universitaire Domaine Universitaire du Sart-Tilman B-4000 Liege, elgium Tel.: + 32 (4) 366.71.66 Fax: 32 (4) 366.70.69 E-mail: T.Defechereux@chu.ulg.ac.be

Aims: To evaluate aspects of the current practice of sentinel lymph node (SLN) pathology in breast cancer via a questionnaire based survey, to recognise major issues that the European guidelines for mammography screening should address in the next revision. Methods: A questionnaire was circulated by mail or electronically by the authors in their respective countries. Replies from pathology units dealing with SLN specimens were evaluated further. Results: Of the 382 respondents, 240 European pathology units were dealing with SLN specimens. Sixty per cent of these units carried out intraoperative assessment, most commonly consisting of frozen sections. Most units slice larger SLNs into pieces and only 12% assess these slices on a single haematoxylin and eosin (HE) stained slide. Seventy one per cent of the units routinely use immunohistochemistry in all cases negative by HE. The terms micrometastasis, submicrometastasis, and isolated tumour cells (ITCs) are used in 93%, 22%, and 71% of units, respectively, but have a rather heterogeneous interpretation. Molecular SLN staging was reported by only 10 units (4%). Most institutions have their own guidelines for SLN processing, but some countries also have well recognised national guidelines. Conclusions: Pathological examination of SLNs throughout Europe varies considerably and is not standardised. The European guidelines should focus on standardising examination. They should recommend techniques that identify metastases > 2 mm as a minimum standard. Uniform reporting of additional findings may also be important, because micrometastases and ITCs may in the future be shown to have clinical relevance.

To assess the variability of oestrogen receptor (ER) testing using immunocytochemistry, centrally stained and unstained slides from breast cancers were circulated to the members of the European Working Group for Breast Screening Pathology, who were asked to report on both slides. The results showed that there was almost complete concordance among readers (kappa=0.95) in ER-negative tumours on the stained slide and excellent concordance among readers (kappa=0.82) on the slides stained in each individual laboratory. Tumours showing strong positivity were reasonably well assessed (kappa=0.57 and 0.4, respectively), but there was less concordance in tumours with moderate and low levels of ER, especially when these were heterogeneous in their staining. Because of the variation, the Working Group recommends that laboratories performing these stains should take part in a external quality assurance scheme for immunocytochemistry, should include a tumour with low ER levels as a weak positive control and should audit the percentage positive tumours in their laboratory against the accepted norms annually. The Quick score method of receptor assessment may also have too many categories for good concordance, and grouping of these into fewer categories may remove some of the variation among laboratories.

Controversies and inconsistencies regarding the pathological work-up of sentinel lymph nodes (SNs) led the European Working Group for Breast Screening Pathology (EWGBSP) to review published data and current evidence that can promote the formulation of European guidelines for the pathological work-up of SNs. After an evaluation of the accuracy of SN biopsy as a staging procedure, the yields of different sectioning methods and the immunohistochemical detection of metastatic cells are reviewed. Currently published data do not allow the significance of micrometastases or isolated tumour cells to be established, but it is suggested that approximately 18% of the cases may be associated with further nodal (non-SN) metastases, i.e. approximately 2% of all patients initially staged by SN biopsy. The methods for the intraoperative and molecular assessment of SNs are also surveyed.

In 1992, a national screening mammography program, including female patients between 50 and 64 years of age, was launched in Luxembourg. The effects of this campaign on the different diagnostic procedures, especially fine needle aspirations (FNA), large core needle biopsies (LCNB), and surgical specimens, were analyzed. From 1983 to 1997, the National Cancer Registry recorded 3167 new cases of invasive female breast cancer, all histologically diagnosed in one central pathology department. In 1996, the population consisted of 418,300 inhabitants (212,900 females). The number of breast cancer, tumor size, the nature of the diagnostic procedures, their diagnostic value as well as the number of physicians, "aspirators", and "biopsists" were evaluated. Between 1992 and 1994, the incidence of invasive breast cancers increased, concomitant with the launching of a National Screening Mammography Program. The diagnosis of in situ cancers tripled, and the mean size of invasive breast cancer decreased from 2.1-2.4 cm to 1.1-1.4 cm. Since 1994, the number of FNA had remained stable, LCNB had increased by 417.5%, and surgical biopsies had decreased by 18.95%. Between 1995 and 1997, 28.37% of 1075 FNA, and only 9.6% of 465 LCNB yielded inadequate samples. FNA were done by 77 different doctors (53.25% being gynecologists) and LCNB by 34 (52.94% being radiologists). The first diagnoses of all invasive cancers (n = 790) were made by using frozen sections from surgical specimens in 58.35% (n = 461), LCNB in 18.23% (n = 144), mastectomy in 10.13% (n = 80), formalin-fixed biopsies in 9.49% (n = 75), and FNA in 3.17% (n = 25). There are beneficial effects (increase in the number of diagnoses of in situ cancer; decrease in tumor sizes) not only for the "target" age group (50-64 years), but also for all female age groups (> 15 years). For quality assurance purposes, it is absolutely recommended to carry out pathological, radiological, and diagnostic work in specialized centers.

Accuracy of frozen section diagnoses of breast lesions after introduction of a national programme in mammographic screening

Education and quality assurance (QA) in breast screening pathology have been encouraged by the Europe Against Cancer programme. As a prerequisite for the set-up of a QA programme in Belgium and in the Grand Duchy of Luxembourg, an inquiry was initiated to evaluate the daily practise in breast pathology, the modalities in handling and analysing breast specimens and the willingness of the pathologists to participate in a QA scheme. Of the 278 mailed questionnaires, 109 confidential and valid questionnaires were returned, meaning a participation rate of 40%. All 109 respondents indicated their willingness to voluntarily participate in the further QA programme. Segmental resections for conservative surgery and excision biopsies ranked first and second, respectively, in examination requests. Of the respondents, 50% complained about the lack of clinical information on the pathology request form. A multidisciplinary team approach for the diagnosis of screen-detected lesions was deemed desirable by 87% of the respondents, but only 16% of them actually participate in such pre-operative meetings. Even more puzzling is that 75% of the respondents report regular unavailability of the control radiogram of the surgical specimen removed for non-palpable lesions. One-quarter to one-third of the pathologists still regularly perform frozen sections on microcalcifications or tumours smaller than 1 cm. However, 81% of the respondents estimate that pre-operative diagnosis is not appropriate for this type of lesion. The results of this inquiry show that the guidelines for the diagnosis of screen-detected breast lesions are not yet fully applied in daily practise. The development of local comprehensive breast teams involving a pathologist should improve the co-ordination between the medical disciplines, represent an important way of disseminating the guidelines on breast screening pathology and stimulate the relay unit to conduct QA programmes.

It is now widely recognised that classifying ductal carcinoma in situ (DCIS) of the breast and diagnosing atypical ductal hyperplasia are associated with significant interobserver variation. Two possible reasons for this inconsistency are differences in the interpretation of specified histological features and field selection where morphology is heterogeneous. In order to investigate the relative contribution of these two factors to inconsistent interpretation of intraductal proliferations, histological sections of 32 lesions were sent to 23 European pathologists followed 3 years later by images of small parts of these sections. Kappa statistics for diagnosing hyperplasia of usual type, atypical ductal hyperplasia and ductal carcinoma in situ were 0.54, 0.35 and 0.78 for sections and 0.47, 0.29 and 0.78 for images, respectively, showing that most of the inconsistency is due to differences in morphological interpretation. Improvements can thus be expected only if diagnostic criteria or methodology are changed. In contrast, kappa for classifying DCIS by growth pattern was very low at 0.23 for sections and better at 0.47 for images, reflecting the widely recognised variation in the growth pattern of DCIS. Higher kappa statistics were obtained when any mention of an individual growth pattern was included in that category, thus allowing multiple categories per case; but kappa was still higher for images than sections. Classifying DCIS by nuclear grade gave kappa values of 0.36 for sections and 0.49 for images, indicating that intralesional heterogeneity has hitherto been underestimated as a cause of inconsistency in classifying DCIS by this method. More rigorous assessment of the proportions of the different nuclear grades present could lead to an improvement in consistency.

It is now widely recognised that classifying ductal carcinoma in situ (DCIS) of the breast and diagnosing atypical ductal hyperplasia are associated with significant interobserver variation. Two possible reasons for this inconsistency are differences in the interpretation of specified histological features and field selection where morphology is heterogeneous. In order to investigate the relative contribution of these two factors to inconsistent interpretation of intraductal proliferations, histological sections of 32 lesions were sent to 23 European pathologists followed 3 years later by images of small parts of these sections. Kappa statistics for diagnosing hyperplasia of usual type, atypical ductal hyperplasia and ductal carcinoma in situ were 0.54, 0.35 and 0.78 for sections and 0.47, 0.29 and 0.78 for images, respectively, showing that most of the inconsistency is due to differences in morphological interpretation. Improvements can thus be expected only if diagnostic criteria or methodology are changed. In contrast, kappa for classifying DCIS by growth pattern was very low at 0.23 for sections and better at 0.47 for images, reflecting the widely recognised variation in the growth pattern of DCIS. Higher kappa statistics were obtained when any mention of an individual growth pattern was included in that category, thus allowing multiple categories per case; but kappa was still higher for images than sections. Classifying DCIS by nuclear grade gave kappa values of 0.36 for sections and 0.49 for images, indicating that intralesional heterogeneity has hitherto been underestimated as a cause of inconsistency in classifying DCIS by this method. More rigorous assessment of the proportions of the different nuclear grades present could lead to an improvement in consistency.

A detailed analysis of the consistency with which pathologists from 12 different European countries diagnose and classify breast disease was undertaken as part of the quality assurance programme of the European Breast Screening Pilot Network funded by the Europe against Cancer Programme. Altogether 107 cases were examined by 23 pathologists in 4 rounds. Kappa (κ) statistics for major diagnostic categories were: benign (not otherwise specified) 0.74, atypical ductal hyperplasia (ADH) 0.27, ductal carcinoma in situ (DCIS) 0.87 and invasive carcinoma 0.94. ADH was the majority diagnosis in only 2 cases but was diagnosed by at least 2 participants in another 14, in 9 of which the majority diagnosis was benign (explaining the relatively low κ for this category), DCIS in 4 (all low nuclear grade) and invasive carcinoma (a solitary 1-mm focus) in 1. The histological features of these cases were extremely variable; although one feature that nearly all shared was the presence of cells with small, uniform, hyperchromatic nuclei and a high nucleo-cytoplasmic ratio. The majority diagnosis was DCIS in 33 cases; κ for classifying by nuclear grade was 0.38 using three categories and 0.46 when only two (high and other) were used. When ADH was included with low nuclear grade DCIS there was only a slight improvement in κ. Size measurement of DCIS was less consistent than that of invasive carcinoma.The majority diagnosis was invasive carcinoma in 57 cases, the size of the majority being 100% in 49. The remainder were either special subtypes (adenoid cystic, tubular, colloid, secretory, ductal/medullary) or possible microinvasive carcinomas. Subtyping was most consistent for mucinous (κ, 0.92) and least consistent for medullary carcinomas (κ, 0.56). Consistency of grading using the Nottingham method was moderate (κ=0.53) and consistency of diagnosing vascular invasion, fair (κ=0.38). There was no tendency for consistency to improve from one round to the next, suggesting that further improvements are unlikely without changes in guidelines or methodology.

This study was carried out to evaluate the reliability of a diagnostic approach with close cooperation between radiologists and surgeons for minimal breast disease. From 1993 to 1995, 152 evaluable patients with non palpable breast lesions were examined by mammography and their lesion was localized with a hook wire before being referred to the surgeon for biopsy. Comparison of mammography findings with pathological diagnosis indicated a good predictive value for benign lesions with only 8% non concordant diagnosis and a rather low predictive value in case of suspect mammograms with only 64% positive diagnosis. With hook-guided breast biopsy, a correct diagnosis was established in 93% of the cases. The remaining breast samples were either non contributory or necessitated a second biopsy. Several recommendations are proposed for improving accuracy of breast sampling such as securing the hook into the gland, orienting the limits of resection, sending specimen for X-ray study and inking the margins for the pathologist. This field experience revealed that some progress, are to be made in diagnosis in particular by standardization of mammography and pathological criteria, more precise localization of the lesions with the hook and more refined surgical techniques for breast biopsy.

Details of a proposed new classification for ductal carcinoma in situ (DCIS) are presented. This is based, primarily, on cytonuclear differentiation and, secondarily, on architectural differentiation (cellular polarisation). Three categories are defined. First is poorly differentiated DCIS composed of cells with very pleomorphic, irregularly spaced nuclei, with coarse, clumped chromatin, prominent nucleoli, and frequent mitoses. Architectural differentiation is absent or minimal. The growth pattern is solid or pseudo-cribriform and -micropapillary (without cellular polarisation). Necrosis is usually present. Calcification, when present, is amorphous. Second, at the other end of the spectrum is well-differentiated DCIS, composed of cells with monomorphic, regularly spaced nuclei containing fine chromatin, inconspicuous nucleoli, and few mitoses. The cells show pronounced polarisation with orientation of their apical border towards intercellular spaces usually resulting in cribriform, micropapillary and clinging patterns, although a solid pattern of well-differentiated DCIS also occurs. Necrosis is uncommon. Calcifications, when present, are usually psammomatous. The third category, intermediately differentiated DCIS, is composed of cells showing some pleomorphism but not so marked as in the poorly differentiated group. There is, however, always evidence of polarization around intercellular spaces, although this is not so pronounced as in the well-differentiated group. These two criteria, cytonuclear differentiation and architectural differentiation, have been found to be more consistent throughout a DCIS lesion than previously employed criteria of architectural pattern or the presence or absence of necrosis.

In a prospective study 200 primary human breast cancer specimens were analysed for epidermal growth factor receptor (EGFR) content by means of a multiple point ligand binding assay, proposed by the EORTC Receptor Study Group to be the standard EGFR assay. In 54% of the tumours the presence of saturable high affinity binding sites for epidermal growth factor could be demonstrated. The median EGFR level was 34 fmol/mg of membrane protein, the median Kd 0.50 nmd. Univariate analysis of the EGFR data stratified according to patient age, menopausal status, tumour size, axillary lymph node status, histological tumour type, tumour differentiation grade or the tumours' steroid hormone receptor status showed EGFR to be positively associated with younger age (P = 0.03), tumour dedifferentiation (P = 0.04) and steroid hormone receptor negativity (P less than 0.001). No association between EGFR and menopausal status, tumour size, axillary lymphnode status or histological tumour type could be demonstrated.