HER2 in well differentiated breast cancer: is testing necessary?

Clinicopathological features of and neoadjuvant therapy for human epidermal growth factor receptor 2-positive classic invasive lobular carcinoma

Human epidermal growth factor receptor 2 (HER2)-positive classic invasive lobular carcinoma (ILC) is a rare entity, and its specific pathological characteristics and clinical behavior are unclear. Therefore, we retrospectively investigated the clinicopathological features of HER2-positive classic ILC and described HER2-targeted neoadjuvant chemotherapy outcome. Fourteen HER2-positive classic ILC cases were identified, their clinicopathological data were collected, and their clinical management was investigated. In general, HER2 positivity is associated with higher grade carcinoma in ductal lesions; however, our 14 cases had typical morphologic features of classic ILC. We did not identify unique morphologic features in HER2-positive classic ILC with the clinicopathological parameters examined, including age, menopausal status, histological grade, and hormone receptor status. Four of six patients who received HER2-targeted neoadjuvant chemotherapy had a pathological complete or partial response. Based on our findings, clinicopathological features of classic ILC may not predict HER2 overexpression or amplification. HER2-targeted neoadjuvant chemotherapy was effective against some HER2-positive classic ILCs. Taken together, these results demonstrate that HER2 immunohistochemistry and fluorescence in situ hybridization should be considered for all ILC patients regardless of subtype.

Diagnostics and Therapeutics in Targeting HER2 Breast Cancer: A Novel Approach

Breast cancer is one of the most commonly occurring cancers in women globally and is the primary cause of cancer mortality in females. BC is highly heterogeneous with various phenotypic expressions. The overexpression of HER2 is responsible for 15-30% of all invasive BC and is strongly associated with malignant behaviours, poor prognosis and decline in overall survival. Molecular imaging offers advantages over conventional imaging modalities, as it provides more sensitive and specific detection of tumours, as these techniques measure the biological and physiological processes at the cellular level to visualise the disease. Early detection and diagnosis of BC is crucial to improving clinical outcomes and prognosis. While HER2-specific antibodies and nanobodies may improve the sensitivity and specificity of molecular imaging, the radioisotope conjugation process may interfere with and may compromise their binding functionalities. Aptamers are single-stranded oligonucleotides capable of targeting biomarkers with remarkable binding specificity and affinity. Aptamers can be functionalised with radioisotopes without compromising target specificity. The attachment of different radioisotopes can determine the aptamer's functionality in the treatment of HER2(+) BC. Several HER2 aptamers and investigations of them have been described and evaluated in this paper. We also provide recommendations for future studies with HER2 aptamers to target HER2(+) BC.

Clinicopathologic features of unexpectedly HER2 positive breast carcinomas: An institutional experience

Human epidermal growth factor receptor 2 (HER2) overexpression occurs in 15-20 % of all breast carcinomas. These tumors are usually high-grade which often correlates with reduced overall survival and increased rates of recurrence. In a retrospective review, we identified 19 cases of unexpectedly HER2 positive (by immunohistochemistry and/or fluorescence in-situ hybridization) invasive breast carcinomas on core needle biopsies from a registry at Northwestern Memorial Hospital. These cases included low-grade tumors, invasive lobular carcinomas, classic type, and invasive carcinomas with special subtype features. Twelve of the tumors were histologic grade 1 and 7 were histologic grade 2. One of the grade 1 tumors had tubular features (8 %), 1 had cribriform features (8 %), 2 had mucinous features (17 %), 2 were invasive lobular carcinomas, classic type (17 %), and the rest were invasive carcinoma, no special type (50 %). The histologic grade 2 tumors included 5 invasive lobular carcinomas, classic type (71 %) and 2 invasive ductal carcinomas with mucinous features (29 %). By immunohistochemistry, 13 (65 %) were HER2 score 3+, 7 were score 2+ (35 %), and reflex fluorescence in-situ hybridization (FISH) testing showed amplification in 6 cases, with 1 equivocal case amplified on excision. Despite the HER2 positive status in the selected cases, no unique morphologic features that would indicate aggressive behavior were identified. In clinical follow up, two patients were found to have recurrences, five had lymph node metastasis, and one had distant metastasis. None of the patients with recurrent disease were treated with trastuzumab, despite their positive HER2 results. These findings support that our population of HER2 positive carcinomas showed a similar rate of lymph node metastases and recurrence as poorly-differentiated tumors, supporting HER2 positivity as a poor prognostic indicator, irrespective of morphologic features. We recommend continuing to test all breast cancers, regardless of grade or special subtype features, to provide the most comprehensive treatment and prognostic information for both clinicians and patients.

Frequency, Clinicopathologic Characteristics, and Follow-up of HER2-Positive Nonpleomorphic Invasive Lobular Carcinoma of the Breast

OBJECTIVES

To investigate human epidermal growth factor receptor 2 (HER2)-positive nonpleomorphic invasive lobular carcinoma (ILC), which has rarely been addressed.

METHODS

Clinicopathologic characteristics and follow-up of HER2-positive nonpleomorphic ILCs were collected and compared to those of HER2-negative counterparts.

RESULTS

Twenty-one cases of HER2-positive nonpleomorphic ILCs were identified, 6.3% of the study population. Compared to HER2-negative nonpleomorphic ILC, patients with HER2 positivity were older (P < .05), likely to be hormonal receptor negative (P < .01), and had higher histologic grade and angiolymphatic invasion (P < .01). HER2 positivity in nonpleomorphic ILCs was associated with higher recurrence/metastasis with hazard ratio of 2.03 (P < .05). No patient who received neoadjuvant therapy achieved pathologic complete response, and HER2-targeted therapy tended to reduce recurrence/metastasis in patients with HER2-positive nonpleomorphic ILC.

CONCLUSIONS

Our results highlight the existence of HER2 positivity in nonpleomorphic ILCs and reinforce that HER2 is associated with worse prognosis in nonpleomorphic ILC.

Well-differentiated invasive breast cancers with equivocal HER2 immunohistochemistry: what is the yield of routine reflex in-situ hybridization testing?

AIMS

The 2013 American Society of Clinical Oncology and the College of American Pathologists (ASCO/CAP) HER2 guidelines recommend testing all invasive breast cancers for HER2, typically with immunohistochemistry (IHC) followed by in-situ hybridization (ISH) when IHC is equivocal. As well-differentiated breast cancers are rarely HER2-positive, we assessed the value of routine reflex HER2 ISH testing for this subset of breast cancers.

METHODS AND RESULTS

We collected HER2 IHC 2+ cases and fluorescence in-situ hybridization (FISH) data from primary breast cancers with well-differentiated tumour types (grade 1 ductal carcinomas, classic lobular carcinomas, tubular, cribriform and pure mucinous carcinomas) at our centre from 2010 to 2015. Haematoxylin and eosin (H&E) and IHC slides were reviewed to confirm tumour type, grade and IHC score based on ASCO/CAP 2013 guidelines and their recent revisions. Of 4633 invasive carcinomas, 1133 had a well-differentiated tumour type; 177 of these were HER2 IHC equivocal, three of which were low-level amplified by FISH (0.3% of all well-differentiated tumours). One amplified case was classic invasive lobular carcinoma and two were invasive ductal carcinomas, grade 1. One amplified case had chromosome 17 monosomy, and one was rescored as HER2 IHC 1+ upon review. 'Basolateral' staining was noted in one amplified case and in 65 of 174 (37.4%) non-amplified cases. This incomplete membranous staining pattern was observed in the majority of invasive ductal carcinomas that were rescored as 1+ according to the revised 2013 guidelines.

CONCLUSIONS

The rate of HER2 amplification among well-differentiated breast cancers is very low. Basolateral staining in well-differentiated tumours may be overinterpreted as HER2 IHC 2+, but is rarely associated with HER2 amplification.

Characteristics of HER2-positive breast cancer diagnosed following the introduction of universal HER2 testing

The aim of this study was to determine the impact of universal HER2 testing on the clinico-pathologic profile of HER2+ breast cancer. Data were extracted from breast cancer pathology reports spanning two periods: before (2003/4, n = 379), and after (2008/9, n = 560) the introduction of universal testing. In 2003/4, 43.3% of breast cancers were tested for HER2 with 16% of tested cases HER2+. In 2008/9, 98.4% of cases were tested with 14.7% HER2+. In 2008/9, HER2+ status was associated with younger age, higher grade, increased tumour size, lymph node involvement, negative oestrogen and/or progesterone receptor status. HER2+ cases diagnosed in 2003/4 were not significantly different in respect of these features. The rate of HER2+ breast cancer amongst screen detected cases in 2008/9 was 8.3%. The phenotype of HER2+ breast cancer was stable following the introduction of universal testing. The overall rate of HER2+ breast cancer was influenced by screen detection.

Classical-type invasive lobular carcinoma with HER2 overexpression: clinical, histologic, and hormone receptor characteristics

The majority of invasive lobular carcinomas (ILCs) express estrogen receptor (ER) and progesterone receptor (PR) but lack ERBB2 (HER2) amplification. HER2 overexpression is traditionally considered to occur in the pleomorphic variant of ILCs. We describe 12 cases of classical-type ILCs with HER2 overexpression in a 3-year period. All tumors displayed the characteristic morphologic features of classical ILC with uniform cells and discohesive growth patterns. The lobular phenotype was confirmed by the absence of E-cadherin staining. Multiple variables regarding clinical, histologic, and hormone receptor characteristics of tumors were evaluated and compared with a set of HER2- classical ILCs. The study identified 2 main pathologic features associated with HER2 overexpression in classical type ILC: histiocytoid morphologic features and absence of PR expression. ER is still expressed in HER2+ classical ILCs, although the level of expression is significantly reduced compared with the HER2- cases. The implications of the findings are discussed.

Guidelines for HER2 testing in breast cancer: a national consensus of the Spanish Society of Pathology (SEAP) and the Spanish Society of Medical Oncology (SEOM)

Identifying breast cancers with HER2 overexpression or amplification is critical as these usually imply the use of HER2-targeted therapies. DNA (amplification) and protein (overexpression) HER2 abnormalities usually occur simultaneously and both in situ hybridisation and immunohistochemistry may be accurate methods for the evaluation of these abnormalities. However, recent studies, including those conducted by the Association for Quality Assurance of the Spanish Society of Pathology, as well as the experience of a number of HER2 testing National Reference Centres have suggested the existence of serious reproducibility issues with both techniques. To address this issue, a joint committee from the Spanish Society of Pathology (SEAP) and the Spanish Society of Medical Oncology (SEOM) was established to review the HER2 testing guidelines. Consensus recommendations are based not only on the panellists' experience, but also on previous consensus guidelines from several countries, including the USA, the UK and Canada. These guidelines include the minimal requirements that pathology departments should fulfil in order to guarantee proper HER2 testing in breast cancer. Pathology laboratories not fulfilling these standards should make an effort to meet them and, until then, are highly encouraged to submit to reference laboratories breast cancer samples for which HER2 determination has clinical implications for the patients.

Oncoprotein HCCR-1 expression in breast cancer is well correlated with known breast cancer prognostic factors including the HER2 overexpression, p53 mutation, and ER/PR status

Background

Oncoprotein HCCR-1 functions as a negative regulator of the p53 and contributes breast tumorigenesis. The serum HCCR-1 assay is useful in diagnosing breast cancer and mice transgenic for HCCR developed breast cancers. But it is unknown how HCCR-1 contributes to human breast tumorigenesis.

Methods

Oncogene HCCR-1 expression levels were determined in normal breast tissues, breast cancer tissues and cancer cell lines. We examined whether HCCR-1 protein expression in breast cancer is related to different biological characteristics, including ER, PR, p53 genotype, and HER2 status in 104 primary breast cancer tissues using immunohistochemical analyses.

Results

HCCR-1 was upregulated in breast cancer cells and tissues compared with normal breast tissues. In this study, overexpression of HCCR-1 was well correlated with known breast cancer prognostic markers including the presence of steroid receptors (ER and PR), p53 mutation and high HER2 overexpression. HCCR-1 was not detected in the ER-negative, PR-negative, p53 negative and low HER2 breast cancer tissues. These data indicate that the level of HCCR-1 in breast cancer tissues is relatively well correlated with known breast cancer factors, including the HER2 overexpression, p53 mutation, and ER/PR status.

Conclusion

Determination of HCCR-1 levels as options for HER2 testing is promising although it needs further evaluation.