David J. Dabbs

Breast cancer prognostic classification in the molecular era: the role of histological grade

Breast cancer is a heterogeneous disease with varied morphological appearances, molecular features, behavior, and response to therapy. Current routine clinical management of breast cancer relies on the availability of robust clinical and pathological prognostic and predictive factors to support clinical and patient decision making in which potentially suitable treatment options are increasingly available. One of the best-established prognostic factors in breast cancer is histological grade, which represents the morphological assessment of tumor biological characteristics and has been shown to be able to generate important information related to the clinical behavior of breast cancers. Genome-wide microarray-based expression profiling studies have unraveled several characteristics of breast cancer biology and have provided further evidence that the biological features captured by histological grade are important in determining tumor behavior. Also, expression profiling studies have generated clinically useful data that have significantly improved our understanding of the biology of breast cancer, and these studies are undergoing evaluation as improved prognostic and predictive tools in clinical practice. Clinical acceptance of these molecular assays will require them to be more than expensive surrogates of established traditional factors such as histological grade. It is essential that they provide additional prognostic or predictive information above and beyond that offered by current parameters. Here, we present an analysis of the validity of histological grade as a prognostic factor and a consensus view on the significance of histological grade and its role in breast cancer classification and staging systems in this era of emerging clinical use of molecular classifiers.

Basal-like and triple-negative breast cancers: a critical review with an emphasis on the implications for pathologists and oncologists

Breast cancer is a heterogeneous disease encompassing a variety of entities with distinct morphological features and clinical behaviors. Although morphology is often associated with the pattern of molecular aberrations in breast cancers, it is also clear that tumors of the same histological type show remarkably different clinical behavior. This is particularly true for ‘basal-like cancer’, which is an entity defined using gene expression analysis. The purpose of this article was to review the current state of knowledge of basal-like breast cancers, to discuss the relationship between basal-like and triple-negative breast cancers, and to clarify practical implications of these diagnoses for pathologists and oncologists.

Androgen receptor in breast cancer: expression in estrogen receptor-positive tumors and in estrogen receptor-negative tumors with apocrine differentiation.

Androgens exert growth inhibitory effects on estrogen receptor and progesterone receptor-negative breast cancer cell lines that show androgen receptor expression. These laboratory findings may be translated into inexpensive alternative therapies for hormone receptor-negative invasive breast cancers. Our aim was to systematically evaluate androgen receptor expression by immunohistochemistry in invasive breast cancers. Androgen receptor (clone AR441, Dako) expression was analyzed on 189 well-characterized consecutive invasive breast carcinomas represented with threefold redundancy on tissue microarrays. Androgen receptor expression was semi-quantitated using a histochemical score-like method and a score >10 was considered positive. Of the 189 consecutive invasive breast cancers, 151 (80%) were positive and 38 (20%) were negative for androgen receptor. The majority (95%) of estrogen receptor-positive tumors were also androgen receptor positive. Of the estrogen receptor-negative tumors, androgen receptor reactivity was seen in 3 of 30 (10%) triple-negative cases and in 5/8 (63%) estrogen receptor-negative/progesterone receptor-negative/HER2+ cases. Six of eight estrogen receptor-negative/androgen receptor-positive cases showed apocrine differentiation. Androgen receptor expression in estrogen receptor-positive cases was associated with smaller tumor size (P=0.0001), lower Nottingham grade (P=0.002) and less frequent tumor cell necrosis (P=0.0001). Androgen receptor expression in estrogen receptor-negative tumors was associated with lower Nottingham grade (P=0.005) and apocrine differentiation (P=0.039). In conclusion, most estrogen receptor-positive breast tumors also express androgen receptor. Androgen receptor expression in estrogen receptor-negative/progesterone receptor-negative/HER2+ tumors (which commonly show apocrine differentiation) and a subset of triple - negative apocrine tumors suggest that these tumors together comprises the ‘molecular apocrine’ group described previously. However, these findings should be further confirmed on larger series of triple-negative and estrogen negative/progesterone negative/HER2+ tumors. Androgen receptor-targeted therapy in estrogen/progesterone receptor-negative tumors may provide an inexpensive alternative to usual high-dose chemotherapy with or without trastuzumab.

Mammaglobin vs GCDFP-15 : An immunohistologic validation survey for sensitivity and specificity

There are limited data that compare the usefulness of mammaglobin with gross cystic disease fluid protein-15 (GCDFP-15) in the identification of breast carcinomas. Whole tissue sections of 29 breast carcinomas with matched lymph node metastases and 63 breast carcinomas on tissue microarray were stained with mammaglobin cocktail and GCDFP-15 antibodies. In addition, tissue microarrays (US Biomax, Rockville, MD) containing 544 different human tumors were also stained with the mammaglobin antibody cocktail. Positive staining was seen in 67 (55.4%) of 121 breast carcinomas with mammaglobin and in 28 cases (23.1%) with GCDFP-15. In the majority of cases, the staining intensity and number of cells staining were higher with mammaglobin than with GCDFP-15. Positive mammaglobin staining was also seen in 44 (8.1%) of 544 nonbreast tumors. Mammaglobin is a more sensitive marker than GCDFP-15 for breast carcinoma; however, it lacks the specificity of GCDFP-15.

Histopathologic variables predict Oncotype DX recurrence score.

Oncotype DX™ is a commercially available reverse transcriptase-polymerase chain reaction based assay that provides a Recurrence Score (RS) and has been shown to provide prognostic and predictive information in estrogen receptor-positive lymph node-negative breast cancers. Independent studies of its utility in routine practice are lacking. Slides and surgical pathology reports from 42 cases of breast carcinomas evaluated by Oncotype DX™ were retrospectively reviewed to determine patient age, tumor size, histologic grade, estrogen and progesterone receptor (ER and PR) and ERBB2 (HER-2/neu) data, with ER and PR reported as a semi-quantitative score reflecting both intensity of staining and proportion of positive cells. We show here that Recurrence Score is significantly correlated with tubule formation, nuclear grade, mitotic count, ER immunohistochemical score, PR immunohistochemical score, and HER-2/neu status, and that the equation RS=13.424+5.420 (nuclear grade) +5.538 (mitotic count) −0.045 (ER immunohistochemical score) −0.030 (PR immunohistochemical score) +9.486 (HER-2/neu) predicts the Recurrence Score with an R2 of 0.66, indicating that the full model accounts for 66% of the data variability. Although the Oncotype DX™ Recurrence Score holds potential, further validation of its independent value beyond that of histopathologic analysis is necessary before it can be implemented in clinical decision making.

Basal phenotype of ductal carcinoma in situ: recognition and immunohistologic profile.

The basal phenotype of breast carcinoma was demonstrated from a study of gene expression profiles, which demonstrated five carcinoma phenotypes with differing immunohistologic profiles and outcomes. The basal phenotype, so-named because of an immunohistologic profile that is similar to myoepithelial cells of the breast, has poor outcomes. While the invasive basal phenotype has been described, there is a paucity of literature regarding the existence or recognition of a precursor lesion. We searched our CoPath database for breast carcinomas in the age group of 37 years or less, and this yielded 98 cases from the years 2001 to April 2006. Pathology reports were screened for those cases that were negative for estrogen and progesterone receptors and HER-2/neu (triple negative). A total of 16 cases (16/98, 16%) fulfilled these criteria. Histology was reviewed and immunostains were performed for Cytokeratins 14, 17, and 5/6, vimentin, EGFR, c-kit, smooth muscle actin and p63. All 16 cases had a high-grade invasive ductal carcinoma, Nottingham score 9/9, with geographic necrosis, good circumscription and lymphoid infiltrates. Of the 16 cases, 13 exhibited at least one area of ductal carcinoma in situ (DCIS). The DCIS types were solid, flat or micropapillary, high nuclear grade, with comedonecrosis and invariably associated with intense lymphoid inflammatory cell infiltration. Of 16 invasive cases, 14 (88%) were positive for CK14, CK17, CK5/6 and EGFR; 94% were vimentin positive, while half or less of cases were positive for smooth muscle actin, c-kit or p63. All of the DCIS components demonstrated the same immunohistologic profile as the invasive component. A DCIS component of solid, flat or micropapillary type exists in the basal phenotype of breast carcinoma, and it demonstrates the same immunophenotype as the invasive carcinoma, typically positive for CK5/6, CK14, CK17, vimentin and EGFR, but negative for ER/PR and HER-2/neu.

High False-Negative Rate of HER2 Quantitative Reverse Transcription Polymerase Chain Reaction of the Oncotype DX Test: An Independent Quality Assurance Study

PURPOSE HER2 (ERBB2) status is an important prognostic and predictive marker in breast carcinoma. In recent years, Genomic Health (GHI), purveyors of the Oncotype DX test, has been separately reporting HER2 by reverse transcription polymerase chain reaction (RT-PCR) to oncologists. Because of the lack of independent evaluation, this quality assurance study was undertaken to define the concordance rate between immunohistochemistry (IHC)/fluorescent in situ hybridization (FISH) and GHI RT-PCR HER2 assay. METHODS All patients at three participating laboratories (Magee-Womens Hospital [Pittsburgh, PA], Cleveland Clinic [Cleveland, OH], and Riverside Methodist Hospital [Columbus, OH]) with available HER2 RT-PCR results from GHI were included in this study. All IHC-positive and equivocal patient cases were further evaluated and classified by FISH at respective laboratories. RESULTS Of the total 843 patient cases, 784 (93%) were classified as negative, 36 (4%) as positive, and 23 (3%) as equivocal at the three institutions using IHC/FISH. Of the 784 negative patient cases, 779 (99%) were also classified as negative by GHI RT-PCR assay. However, all 23 equivocal patient cases were reported as negative by GHI. Of the 36 positive cases, only 10 (28%; 95% CI, 14% to 45%) were reported as positive, 12 (33%) as equivocal, and 14 (39%) as negative. CONCLUSION There was an unacceptable false-negative rate for HER2 status with GHI HER2 assay in this independent study. This could create confusion in the decision-making process for targeted treatment and potentially lead to mismanagement of patients with breast cancer if only GHI HER2 information is used.

Immunohistochemical surrogate markers of breast cancer molecular classes predicts response to neoadjuvant chemotherapy: a single institutional experience with 359 cases.

Complete pathologic response to neoadjuvant chemotherapy (NACT) is predominantly seen in “ERBB2” and “basal‐like” tumors using expression profiling. We hypothesize that a similar response could be predicted using semiquantitative immunohistochemistry for estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER2).

Consensus recommendations on estrogen receptor testing in breast cancer by immunohistochemistry.

Estrogen receptor (ER) status in breast cancer is currently the most important predictive biomarker that determines breast cancer prognosis after treatment with endocrine therapy. Although immunohistochemistry has been widely viewed as the gold standard methodology for ER testing in breast cancer, lack of standardized procedures, and lack of regulatory adherence to testing guidelines has resulted in high rates of “false-negative” results worldwide. Standardized testing is only possible after all aspects of ER testing—preanalytical, analytical, and postanalytical, have been closely controlled. A meeting of the “ad-hoc committee” of expert pathologists, technologists, and scientists, representing academic centers, reference laboratories, and various agencies, issued standardization testing recommendations, aimed at optimization of clinical ER testing environment, as a step toward improved standardized testing.

Identification of the most sensitive and robust immunohistochemical markers in different categories of ovarian sex cord-stromal tumors.

Different immunohistochemical sex cord-stromal markers have been previously studied in various types of ovarian sex cord-stromal tumors; however, the sensitivity for sex cord-stromal lineage may vary between markers, and some markers may not be as sensitive in some types of sex cord-stromal tumors compared with other tumors in this spectrum of neoplasms. The goals of this study were to determine which immunohistochemical markers are the most sensitive and immunohistochemically robust for sex cord-stromal lineage within a given type of ovarian sex cord-stromal tumor, and to establish whether there are substantial differences of expression of these markers between different types of sex cord-stromal tumors. Immunohistochemical stains for markers which have known variable specificity for sex cord-stromal lineage [inhibin, calretinin, MART-1/melan-A, CD99, steroidogenic factor 1 (SF-1, adrenal 4-binding protein), and WT1], were performed in 127 cases of 5 different types of ovarian sex cord-stromal tumors: adult granulosa cell tumor (n=32), Sertoli cell tumor (n=27), Sertoli-Leydig cell tumor (n=18), steroid cell tumor (n=25), and fibroma/fibrothecoma (n=25). All cases in each type of sex cord-stromal tumor expressed SF-1. Inhibin and calretinin were expressed in all groups of tumors but with a lesser frequency (56% to 100% and 36% to 100% of cases, respectively). All types of tumors except steroid cell tumor expressed WT1. Fibroma/fibrothecoma was the only type of tumor that did not express CD99. The only tumor groups that showed expression of MART-1 were Sertoli-Leydig cell tumor (restricted to the Leydig cell component) and steroid cell tumor (94% and 96% of cases, respectively). The type of sex cord-stromal tumor that was least frequently positive for several of the different markers studied was fibroma/fibrothecoma. Among all tumor groups combined, inhibin and WT1 were the 2 markers showing the most diffuse expression. Likewise, the single marker showing the most optimal combination of diffuse and strong staining (immunohistochemical composite score: possible range, 1 to 12) varied between tumors: adult granulosa cell tumor-inhibin (score 10.0); Sertoli cell tumor-WT1 (score 10.8); Sertoli-Leydig cell tumor (Sertoli cell component)-WT1 (score 10.4); steroid cell tumor-inhibin (score 11.2); and fibroma/fibrothecoma-WT1 (score 8.9). We conclude that most immunohistochemical sex cord-stromal markers have sufficient sensitivity for sex cord-stromal lineage. Although each of the different types of sex cord-stromal tumors has a slightly unique immunoprofile in terms of frequency and extent of expression, these differences are relatively minor for most types of tumors with certain exceptions (eg, WT1 is not diagnostically useful in steroid cell tumor; CD99 is not diagnostically useful in fibroma/fibrothecoma; the only sex cord-stromal tumor for which MART-1 is diagnostically useful is steroid cell tumor; inhibin and calretinin are less diagnostically useful in fibroma/fibrothecoma than in the other types of tumors, but expression in fibrothecoma was higher than in fibroma). SF-1 is the most sensitive sex cord-stromal marker among the most common types of sex cord-stromal tumors. Given the findings relating to sensitivity and extent of expression in this study, and known specificity in the literature, the most informative sex cord-stromal markers to be used for the distinction from nonsex cord-stromal tumors are inhibin, calretinin, SF-1, and WT1 (the exact number of markers to be used should be based on the degree of difficulty of the case and level of experience of the pathologist); however, the utility of immunohistochemistry for the diagnosis of fibroma/fibrothecoma is somewhat limited.