Cytologic assessment of estrogen receptor, progesterone receptor, and HER2 status in metastatic breast carcinoma

Immunocytochemical markers, molecular testing and digital cytopathology for aspiration cytology of metastatic breast carcinoma

Fine-needle aspiration cytology (FNAC) is a versatile diagnostic procedure uniquely suited for tissue biopsy of breast carcinomas and axillary metastases and/or recurrences. With the expanding treatment options and accompanying theragnostic tests, it is crucial to recognize the developments on ancillary testing and digital cytopathology techniques related to aspiration cytology of metastatic breast carcinoma. In this review, we aim to summarize and update the evidence of immunocytochemistry, for the detection of carcinoma cells (epithelial markers), confirmation of breast primary (breast-specific markers), assessment of surrogate immunostains (hormone receptors, ki-67 proliferative index and HER2) and theragnostic biomarkers, with discussion on potential diagnostic pitfalls, followed by the application of molecular tests, and digital cytopathologic techniques for assessing metastatic breast carcinoma in cytology.

Discrepancies in Hormone Receptor and HER2 Expression between Malignant Serous Effusions and Paired Tissues from Primary or Recurrent Breast Cancers

INTRODUCTION

Immunohistochemistry (IHC) for the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) biomarkers has prognostic and therapeutic value in breast cancer. This study aimed to compare the expression of ER, PR, and HER2 between paired malignant effusions and tissue samples of breast cancer.

METHODS

Our electronic archive was searched for all effusions diagnosed as breast carcinomas within a pre-defined period (January 2018-October 2021). Next, their cell blocks (CBs) were subjected to ER, PR, HER2 IHC, or in situ hybridization, in addition to EGFR IHC. The expression of hormone receptors (HRs) and HER2 was subsequently compared between tissue and effusion cytology samples derived from the same patients.

RESULTS

Only 2/76 (2.6%) of the breast cancer patients analyzed showed a malignant effusion at their initial presentation. ER, PR, and HER2 discordance rates between paired malignant effusions and tissue samples obtained at initial diagnosis were 24.3% (17/73), 40.8% (29/71), and 9.1% (6/66), respectively. The HR-/HER2- status was found more often at effusions compared to paired tissue biopsies obtained at initial diagnosis (30/70 vs. 17/70; p < 0.001). In addition, the HR-/HER2- status was significantly associated with an earlier development of a malignant effusion, when found at initial diagnosis (p < 0.001; log-rank test), first recurrence/metastasis (either solid or effusion) (p = 0.012; log-rank test), effusion samples (p = 0.007; log-rank test), and any tumor sample obtained (p = 0.009; log-rank test). Lastly, EGFR overexpression in the HR-/HER2- effusion samples was significantly associated with a shorter post-effusion survival (p = 0.019; log-rank test).

CONCLUSION

Serous effusion cytology provides high-quality material for ancillary techniques, especially when CBs are prepared, reflecting cancer heterogeneity.

A New Landscape of Testing and Therapeutics in Metastatic Breast Cancer

Predictive biomarker testing on metastatic breast cancer is essential for determining patient eligibility for targeted therapeutics. The National Comprehensive Cancer Network currently recommends assessment of specific biomarkers on metastatic tumor subtypes, including hormone receptors, HER2, and BRCA1/2 mutations, on all newly metastatic breast cancers subtypes; programmed death-ligand 1 on metastatic triple-negative carcinomas; and PIK3CA mutation status on estrogen receptor-positive carcinomas. In select circumstances mismatch repair protein deficiency and/or microsatellite insufficiency, tumor mutation burden, and NTRK translocation status are also testing options. Novel biomarker testing, such as detecting PIK3CA mutations in circulating tumor DNA, is expanding in this rapidly evolving arena.

Comprehensive Review of Metastatic Breast Carcinoma in Cytology Specimens

Breast carcinomas are known to metastasize to various organs of the human body. Fine needle aspiration cytology or exfoliative cytology often are the standard method for diagnosis at these metastatic sites due to ease of procurement of diagnostic material, accessibility, less complications, high sensitivity, and specificity of diagnosis and evaluation of biomarker status needed to guide future management. This comprehensive review article discusses in detail metastatic patterns, cytomorphology of metastatic breast cancer at different body sites, immunohistochemistry needed for diagnosis of breast carcinoma, sensitivity and specificity of diagnosis and breast biomarker assays in the cytology material.

A New Landscape of Testing and Therapeutics in Metastatic Breast Cancer

Predictive biomarker testing on metastatic breast cancer is essential for determining patient eligibility for targeted therapeutics. The National Comprehensive Cancer Network currently recommends assessment of specific biomarkers on metastatic tumor subtypes, including hormone receptors, HER2, and BRCA1/2 mutations, on all newly metastatic breast cancers subtypes; programmed death-ligand 1 on metastatic triple-negative carcinomas; and PIK3CA mutation status on estrogen receptor-positive carcinomas. In select circumstances mismatch repair protein deficiency and/or microsatellite insufficiency, tumor mutation burden, and NTRK translocation status are also testing options. Novel biomarker testing, such as detecting PIK3CA mutations in circulating tumor DNA, is expanding in this rapidly evolving arena.

Efficacy of anti-HER2 therapy in metastatic breast cancer by discordance of HER2 expression between primary and metastatic breast cancer

PURPOSE

In stage IV breast cancer, the efficacy of human epidermal growth factor receptor 2 (HER2) targeted therapies in cases with discordance in HER2 expression between primary and metastatic site is not well known. We studied progression free (PFS) and overall survival (OS) by HER2 concordance when treating women with taxane-trastuzumab (± pertuzumab) in first or second line and trastuzumab-emtansine (T-DM1) or capecitabine-lapatinib in later lines.

PATIENTS AND METHODS

Retrospective monocentric study including all breast cancer patients receiving trastuzumab between January 2002 and September 2017 at the University Hospital in Leuven; we selected metastatic patients with an available HER2 status in primary and metastatic site. The Kaplan-Meier method was used for estimating PFS/OS and log-rank test for analyzing between group differences. A Cox model is used for testing difference between groups while correcting for Pertuzumab. Multivariable Cox regression is used to model overall survival as a function group, correcting for possible confounders.

RESULTS

We included 74 patients; 46 had an unchanged HER2 status (positive/positive), 9 lost HER2 (positive/negative), while 19 acquired HER2 amplification (negative/positive). 25 out of 28 cases with a discordant HER2 status were positive for ER and/or PgR in the primary site. HER2 positive/negative cases had a significantly lower PFS for taxane-trastuzumab-(pertuzumab) (PFS = 5.5 months), compared to HER2 positive/positive (PFS 9 months, p = 0.01) and HER2 negative/positive (PFS 14 months, p = 0.01) patients. PFS for later line T-DM1 (n = 30) was significantly higher for the HER2 positive/positive group (PFS 6.0 months) than for the discordant groups HER2 negative/positive (PFS 1.0 month, p = 0.04) and HER2 positive/negative (PFS 1.5 month, p = 0.01). After correcting for possible confounders, the HER2 positive/negative group had a significantly worse OS compared to HER2 positive/positive (HR 0.19, 95% CI 0.08-0.44) and negative/positive (HR 0.15, 95% 0.06-0.38).

CONCLUSION

Conversion of HER2 status was seen in 28 out of 74 cases and was mostly observed in hormone receptor-positive tumors. In contrast to patients with HER2 loss, patients with a positive conversion of HER2 status derived substantial benefit from first line treatment with taxane-trastuzumab-(pertuzumab). This study highlights the importance of re-biopsying the metastatic lesion and changing treatment according to the last HER2 result.

Hormone receptor and HER2 assessment in breast carcinoma metastatic to bone: A comparison between FNA cell blocks and decalcified core needle biopsies

BACKGROUND

Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) guide the clinical management of breast cancer metastases. Decalcification of bone core needle biopsies (CNBs) can affect IHC. In the current study, the authors sought to define whether fine-needle aspiration (FNA) would be a better alternative to CNB for reliable IHC.

METHODS

Patients with breast cancer metastases to bone that were sampled by both CNB and FNA were selected. ER, PR, and HER2 were performed in FNA cell blocks (FNA-CBs) and concurrent decalcified CNBs. Discrepancies were classified as minor when there was a difference of up to 30% nuclear staining in IHC for ER and PR between paired samples and as major when a clinically relevant change was observed (ie, positive vs negative). Quantitative reverse transcriptase-polymerase chain reaction of ESR1 messenger RNA levels was performed on FNA/CNB pairs with discrepancies for ER IHC. IHC status of the primary breast carcinoma was recorded.

RESULTS

Concordance rates for ER, PR, and HER2 were 89%, 67%, and 93%, respectively, between FNA-CB and CNB pairs from 27 patients. Major discrepancies were noted in approximately 11% of FNA/CNB pairs for ER IHC and in 33% of FNA/CNB pairs for PR. ESR1 messenger RNA levels of FNA/CNB matched samples were similar and did not explain the differences in ER IHC expression in the majority of cases. Two of 27 FNA/CNB pairs had different results for HER2 IHC that changed from negative on CNB to equivocal (2+) on FNA-CB. Both cases had prior HER2 amplification by fluorescence in situ hybridization.

CONCLUSIONS

FNA-CB and CNB appear to constitute acceptable methods for the assessment of ER, PR, and HER2 for clinical decision making.

CellBlockistry: Chemistry and art of cell-block making - A detailed review of various historical options with recent advances

Cell-blocks are paraffin-embedded versions of cytology specimens comparable to the formalin-fixed paraffin-embedded (FFPE) tissue from surgical pathology specimens. They allow various elective ancillary studies on a variety of specimens with enhanced cytopathologic interpretation, including opportunity to perform molecular tests. However, different dictionaries and internet search engines primarily project "cellblock" and "cell block" definition in relation to prisons. Most of the top searches lead to information related to "prison cells" followed by a few cytopathology-related searches. Due to this in the current review, it is recommended that the word for cytopathology purposes should be hyphenated and spelled as "cell-block." Cell-blocks have been increasingly indicated on most cytology specimens. Its role is growing further with the ongoing addition of new immunohistochemistry (IHC) markers with technical advances including multicolor IHC and the SCIP (subtractive coordinate immunoreactivity pattern) approach. In addition, it is an important source of tissue for many ancillary studies even as archived material retrospectively at later stage of management if the cell-blocks are improved qualitatively and quantitatively. Because of this, the significance of cell-block is critical with the increasing number of molecular markers standardized predominantly on FFPE tissue. As compared to core biopsies, high-quality cell-blocks prepared with enhanced methodologies predominantly contain concentrated diagnostic tumor cells required for the molecular tests without significant stromal contamination. This review introduces the terminology of CellBlockistry as the science of studying chemistry and the art of achieving quantitatively and qualitatively improved cell-blocks from different types of specimens. The review addresses the cell-block making process as "cell-blocking" and discusses different historical limitations with emphasis on recent advances.