Immunohistochemical assessment of primary breast tumors and metachronous brain metastases, with particular regard to differences in the expression of biological markers and prognosis

Single-center study on clinicopathological and typical molecular pathologic features of metastatic brain tumor

BACKGROUND

The metastatic brain tumor is the most common brain tumor. The aim of this study was to demonstrate the clinicopathological and molecular pathologic features of brain metastases (BM).

METHODS

A total of 269 patients were diagnosed with BM through surgical resection at Seoul St. Mary's Hospital from January 2010 to March 2020. We reviewed the clinicopathological features and molecular status of primary and metastatic brain tissues using immunohistochemistry and molecular pathology results.

RESULTS

Among 269 patients, 139 males and 130 females were included. The median age of primary tumor was 58 years (range, 13 to 87 years) and 86 patients (32.0%) had BM at initial presentation. Median BM free interval was 28.0 months (range, 1 to 286 months). The most frequent primary site was lung 46.5% (125/269), and followed by breast 15.6% (42/269), colorectum 10.0% (27/269). Epidermal growth factor receptor (EGFR) mutation was found in 50.8% (32/63) and 58.0% (40/69) of lung primary and BM, respectively. In both breast primary and breast cancer with BM, luminal B was the most frequent subtype at 37.9% (11/29) and 42.9% (18/42), respectively, followed by human epidermal growth factor receptor 2 with 31.0% (9/29) and 33.3% (14/42). Triple-negative was 20.7% (6/29) and 16.7% (7/42), and luminal A was 10.3% (3/29) and 7.1% (3/42) of breast primary and BM, respectively. In colorectal primary and colorectal cancer with BM, KRAS mutation was found in 76.9% (10/13) and 66.7% (2/3), respectively.

CONCLUSIONS

We report the clinicopathological and molecular pathologic features of BM that can provide useful information for understanding the pathogenesis of metastasis and for clinical trials based on the tumor's molecular pathology.

Molecular aspects of brain metastases in breast cancer

Brain metastases (BM) are a common and devastating manifestation of breast cancer (BC). BM are particularly frequent in the HER2-positive and triple-negative breast cancer phenotypes and usually occur following the metastatic spread to extracranial sites. Several genes mediating BM and biomarkers predicting their risk in BC have been reported in the past decade. These findings have advanced the understanding of BM pathobiology and paved the way for developing new therapeutic strategies but they still warrant a thorough clinical validation. Hence, a better understanding of the mechanistic aspects of BM and delineating the interactions of tumor cells with the brain microenvironment are of utmost importance. This review discusses the molecular basis of the metastatic cascade: the epithelial-mesenchymal transition, cancer, and tumor microenvironment interaction and intravasation, priming of the metastatic niche in the brain, and survival in the new site. We also outline the postulated mechanisms of BC cells' brain tropism. Finally, we discuss advances in the field of biomarkers (both tissue-based and liquid-based) that predict BM from BC.

Receptor discordance among primary tumors, brain metastases and extra-brain metastases in patients with breast cancer

Background: To investigate the expression status of estrogen receptor (ER), progesterone receptor (PR) and HER2 in patients with breast cancer brain metastases (BM). Methods: Patients who underwent craniotomy for BM were included. The status of ER, PR and HER2 (including HER2-low expression) in primary breast tumors (PT), BM and extra-BM (EM) was determined. Results: Between PT and BM, conversion of hormone receptor and HER2 occurred in 28% (30/107) and 12% (10/86) of cases. When considering three-tiered categorization of HER2, the conversion rate reached 31%. In the paired EM and BM (n = 39), the discordance rates were 18%, 3% and 22%, respectively. Conclusion: Receptor discordance was dynamic and relevant, especially using new HER2 categorization.

Estrogen/progesterone receptor and HER2 discordance between primary tumor and brain metastases in breast cancer and its effect on treatment and survival

BACKGROUND

Breast cancer treatment is based on estrogen receptors (ERs), progesterone receptors (PRs), and human epidermal growth factor receptor 2 (HER2). At the time of metastasis, receptor status can be discordant from that at initial diagnosis. The purpose of this study was to determine the incidence of discordance and its effect on survival and subsequent treatment in patients with breast cancer brain metastases (BCBM).

METHODS

A retrospective database of 316 patients who underwent craniotomy for BCBM between 2006 and 2017 was created. Discordance was considered present if the ER, PR, or HER2 status differed between the primary tumor and the BCBM.

RESULTS

The overall receptor discordance rate was 132/316 (42%), and the subtype discordance rate was 100/316 (32%). Hormone receptors (HR, either ER or PR) were gained in 40/160 (25%) patients with HR-negative primary tumors. HER2 was gained in 22/173 (13%) patients with HER2-negative primary tumors. Subsequent treatment was not adjusted for most patients who gained receptors-nonetheless, median survival (MS) improved but did not reach statistical significance (HR, 17-28 mo, P = 0.12; HER2, 15-19 mo, P = 0.39). MS for patients who lost receptors was worse (HR, 27-18 mo, P = 0.02; HER2, 30-18 mo, P = 0.08).

CONCLUSIONS

Receptor discordance between primary tumor and BCBM is common, adversely affects survival if receptors are lost, and represents a missed opportunity for use of effective treatments if receptors are gained. Receptor analysis of BCBM is indicated when clinically appropriate. Treatment should be adjusted accordingly.

KEY POINTS

1. Receptor discordance alters subtype in 32% of BCBM patients.2. The frequency of receptor gain for HR and HER2 was 25% and 13%, respectively.3. If receptors are lost, survival suffers. If receptors are gained, consider targeted treatment.

Subtype switching in breast cancer brain metastases: a multicenter analysis

Background

Breast cancer (BC) brain metastases (BM) can have discordant hormonal or human epidermal growth factor receptor 2 (HER2) expression compared with corresponding primary tumors. This study aimed to describe incidence, predictors, and survival outcomes of discordant receptors and associated subtype switching in BM.

Methods

BCBM patients seen at 4 tertiary institutions who had undergone BM resection or biopsy were included. Surgical pathology reports were retrospectively assessed to determine discordance between the primary tumor and the BCBM. In discordant cases, expression in extracranial metastases was also assessed.

Results

In BM from 219 patients, prevalence of any discordance was 36.3%; receptor-specific discordance was 16.7% for estrogen, 25.2% for progesterone, and 10.4% for HER2. Because estrogen and progesterone were considered together for hormonal status, 50 (22.8%) patients switched subtype as a result; 20 of these switches were HER2 based. Baseline subtype predicted switching, which occurred in up to 37.5% of primary HR+ patients. Moreover, 14.8% of initially HER2-negative patients gained HER2 in the BM. Most (63.6%) discordant patients with extracranial metastases also had discordance between BM and extracranial subtype. Loss of receptor expression was generally associated with worse survival, which appeared to be driven by estrogen loss (hazard ratio = 1.80, P = 0.03). Patients gaining HER2 status (n = 8) showed a nonsignificant tendency toward improved survival (hazard ratio = 0.64, P = 0.17).

Conclusions

In this multicenter study, we report incidence and predictors of subtype switching, the risk of which varies considerably by baseline subtype. Switches can have clinical implications for prognosis and treatment choice.

Picturing Breast Cancer Brain Metastasis Development to Unravel Molecular Players and Cellular Crosstalk

Simple Summary

Breast cancer is a devastating disorder affecting millions of women worldwide. With improved therapeutics for the primary tumor, the appearance of metastasis has been increasing. Breast cancer frequently metastasizes to the brain, constituting a major hurdle without cure and with a poor survival. It is imperative to better understand the mechanisms involved in malignant cell transposition of the brain microvasculature and parenchymal colonization by deciphering the alterations occurring in the tumor and microvascular cells, as well as the occurrence of intercellular communication during the process. We aimed to profile the process of the formation of breast cancer brain metastasis and the timeline of events governing it. We used a specific mouse model of the disease to perform extensive microscopic analyses. We identified phenotypic changes and the activation of relevant molecular players in tumorigenesis, together with vascular alterations, and the occurrence of crosstalk. Our findings unravel putative therapeutic targets to tackle breast cancer brain metastasis.

Abstract

With breast cancer (BC) therapy improvements, the appearance of brain metastases has been increasing, representing a life-threatening condition. Brain metastasis formation involves BC cell (BCC) extravasation across the blood–brain barrier (BBB) and brain colonization by unclear mechanisms. We aimed to disclose the actors involved in BC brain metastasis formation, focusing on BCCs’ phenotype, growth factor expression, and signaling pathway activation, correlating with BBB alterations and intercellular communication. Hippocampi of female mice inoculated with 4T1 BCCs were examined over time by hematoxylin-eosin, immunohistochemistry and immunofluorescence. Well-established metastases were observed at seven days, increasing thereafter. BCCs entering brain parenchyma presented mesenchymal, migratory, and proliferative features; however, with time, they increasingly expressed epithelial markers, reflecting a mesenchymal–epithelial transition. BCCs also expressed platelet-derived growth factor-B, β₄ integrin, and focal adhesion kinase, suggesting autocrine and/or paracrine regulation with adhesion signaling activation, while balance between Rac1 and RhoA was associated with the motility status. Intercellular communication via gap junctions was clear among BCCs, and between BCCs and endothelial cells. Thrombin accumulation, junctional protein impairment, and vesicular proteins increase reflect BBB alterations related with extravasation. Expression of plasmalemma vesicle-associated protein was increased in BCCs, along with augmented vascularization, whereas pericyte contraction indicated mural cells’ activation. Our results provide further understanding of BC brain metastasis formation, disclosing potential therapeutic targets.

Systematic review and meta-analysis of breast cancer brain metastasis and primary tumor receptor expression discordance

Background

Change in hormone receptor (estrogen [ER] and progesterone [PR]) and/or human epidermal growth factor receptor type 2 (HER2) status during the evolutionary course of metastatic breast cancer and the effect of tumor classification subtype switching remain understudied and underappreciated in brain metastasis patients.

Methods

Using preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, a systematic review of series published prior to April 2020 obtained from the Medline database of biopsied or resected breast cancer brain metastasis (BCBM) was performed. Weighted random effects models were used to calculate pooled estimates.

Results

15 full-text articles were included with receptor expression analyses on 1373 patients who underwent biopsy or resection of at least one intracranial lesion to compare to the primary tumor. Primary tumor receptor expression immunophenotypes were 45.0% ER+, 41.0% ER−, 31.0% PR+, 51.0% PR−, 35% HER2+, and 47.0% HER2−. Corresponding BCBM immunophenotypes were 19.0% ER+, 31.0% ER−, 13.0% PR+, 40.0% PR−, 21.0% HER2+, and 26.0% HER2−. On primary/BCBM comparison, 540 patients (42.6%) exhibited discordance in any receptor with 17.0% (95% CI: 13.0%–23.0%) discordant on ER, 23.0% (95% CI: 18.0%–30.0%) discordant on PR, and 12.0% (95% CI: 8.0%–16.0%) discordant on HER2 status. The most common receptor conversions found in BCBM were ER loss 11.0% (95% CI: 8.0%–16.0%), PR loss 15.0% (95% CI: 11.0%–21.0%), and HER2 gain 9.0% (95% CI: 7.0%–11.0%).

Conclusions

BCBM exhibits significant receptor expression discordance in comparison to primary tumors in approximately 40% of patients. Classification patterns need to be analyzed to determine factors predictive of BCBM/primary tumor discordance. Overall, tumor subtype switching and its effect on clinical management remains underappreciated.

Receptor Conversion in Distant Breast Cancer Metastases: A Systematic Review and Meta-analysis

Background

In metastatic breast cancer, hormone and/or human epidermal growth factor receptor 2 (HER2)-targeted therapy decision-making is still largely based on tissue characteristics of the primary tumor. However, a change of estrogen receptor alpha (ERα), progesterone receptor (PR), and HER2 status in distant metastases has frequently been reported. The actual incidence of this phenomenon has been debated.

Methods

We performed a meta-analysis including 39 studies assessing receptor conversion from primary breast tumors to paired distant breast cancer metastases. We noted the direction of change (positive to negative or vice versa) and performed subgroup analyses for different thresholds for positivity, the type of test used to assess HER2 receptor status, and metastasis location-specific differences (two-sided tests).

Results

Overall, the incidence of receptor conversion varied largely between studies. For ERα, PR, and HER2, we found that random effects pooled positive to negative conversion percentages of 22.5% (95% confidence interval [CI] = 16.4% to 30.0%), 49.4% (95% CI = 40.5% to 58.2%), and 21.3% (95% CI = 14.3% to 30.5%), respectively. Negative to positive conversion percentages were 21.5% (95% CI = 18.1% to 25.5%), 15.9% (95% CI = 11.3% to 22.0%), and 9.5% (95% CI = 7.4% to 12.1%). Furthermore, ERα discordance was statistically significantly higher in the central nervous system and bone compared with liver metastases (20.8%, 95% CI = 15.0% to 28.0%, and 29.3%, 95% CI = 13.0% to 53.5%, vs 14.3%, 95% CI = 11.3% to 18.1, P = .008 and P < .001, respectively), and PR discordance was higher in bone (42.7%, 95% CI = 35.1% to 50.6%, P < .001) and liver metastases (47.0%, 95% CI = 41.0% to 53.0%, P < .001) compared with central nervous system metastases (23.3%, 95% CI = 16.0% to 32.6%).

Conclusions

Receptor conversion for ERα, PR, and HER2 occurs frequently in the course of disease progression in breast cancer. Large prospective studies assessing the impact of receptor conversion on treatment efficacy and survival are needed. Meanwhile, reassessing receptor status in metastases is strongly encouraged.

Discordances in ER, PR, and HER2 between primary breast cancer and brain metastasis

When distant metastases are discovered, it is important to determine receptor profiles of these lesions through histologic examination. However, brain metastasis sites are difficult to reach to be routinely biopsied. The purpose of this study was to determine expression profiles of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) in breast cancer brain metastasis (BCBM) and the existence of discordance between primary breast cancer and brain metastasis. A total of 37 patients who underwent craniotomies for metastatic brain tumors arising from breast cancer at National Cancer Center (NCC) of Korea between 2002 and 2014 were retrospectively reviewed. Clinicopathologic data were collected from electronic medical records. Receptor profiles of primary breast cancer and brain metastasis in each patient were identified. Data of ER, PR, and HER2 expression in brain metastasis were available in electronic medical records for 21 (56.8%) of 37 cases. Results of ER, PR, and HER2 expression were positive in 47.6, 42.9, and 38.1% of patients with brain metastasis, respectively. Receptor conversion occurred in 11 (52.4%) of 21 patients (for ER, 9.5%; for PR, 38.1%; for HER2, 23.8%). Overall survival was longer in patients with concordant receptor expression patterns between primary breast cancer and brain lesion compared to that in patients with discordant patterns. However, such difference was not statistically significant (discordant vs. concordant median survival: 19.2 versus 31.1 months, p = 0.181). Receptor conversion in BCBMs was observed in over 50% of Korean patients used in this study. HER2 conversion was observed in 23.8% of patients in this study. Therefore, if resistance to anti-HER2 treatment is suspected in patients with BCBM, biopsy is needed to determine receptor profiles of brain lesion.

Estrogen, progesterone, and HER2/neu receptor discordance between primary and metastatic breast tumours-a review

Discordance in estrogen (ER), progesterone (PR), and HER2/neu status between primary breast tumours and metastatic disease is well recognized. In this review, we highlight how receptor discordance between primary tumours and paired metastasis can help elucidate the mechanism of metastasis but can also effect patient management and the design of future trials. Discordance rates and ranges were available from 47 studies (3384 matched primary and metastatic pairs) reporting ER, PR, and HER2/neu expression for both primary and metastatic sites. Median discordance rates for ER, PR, and HER2/neu were 14 % (range 0-67 %, IQR 9-25 %), 21 % (range 0-62 %, IQR 15-41 %), and 10 % (range 0-44 %, IQR 4-17 %), respectively. Loss of receptor expression was more common (9.17 %) than gain (4.51 %). Discordance rates varied amongst site of metastasis with ER discordance being highest in bone metastases suggesting that discordance is a true biological phenomenon. Discordance rates vary for both the biomarker and the metastatic site. Loss of expression is more common than gain. This can affect patient management as it can lead to a reduction in both the efficacy and availability of potential therapeutic agents. Future studies are recommended to explore both the mechanisms of discordance as well as its impact on patient outcome and management.

Fibroblastic reticular cell tumor of the breast: A case report and review of the literature

Fibroblastic reticular cells (FBRCs) are basic mesenchymal cells that belong to the dendritic cell family. Primary extranodal FBRC tumor (FRCT) cases are rare, with only 19 cases reported in the literature thus far. However, none of these cases originated in the breast tissue. To the best of our knowledge, the present study reported the first FRCT case of the breast in a 57-year-old woman. The patient complained of a painless mass that was located in the right breast and was ~3.5×2.5 cm in size. The patient underwent modified radical mastectomy subsequent to the diagnosis of FRCT after analysis of the lumpectomy specimen. Pathological examination revealed that the tumor was mainly composed of oval and spindle cells, and was infiltrated with lymphocytes and plasma cells. The tumor cells were immunoreactive for vimentin and negative for CD21, CD35 and S-100 protein. Six axillary lymph nodes were found to have been involved. Following surgery, the patient received four cycles of mesna, doxorubicin, ifosfamide and dacarbazine regimen chemotherapy (70 mg adriamycin day 1; 2.0 g ifosfamided days 1-3; 0.4 g dacarbazine day 1-3), which cycled every 21 days. The patient was uneventfully followed-up for 20 months following chemotherapy. In conclusion, the present study reported what appeared to be the first case of primary breast FRCT. The diagnosis, treatment and prognosis details presented in this study will help improve the diagnosis of the disease.