Clinical outcome in pleomorphic lobular carcinoma: a case-control study with comparison to classic invasive lobular carcinoma

Pathway-based signatures predict patient outcome, chemotherapy benefit and synthetic lethal dependencies in invasive lobular breast cancer

BACKGROUND

Invasive Lobular Carcinoma (ILC) is a morphologically distinct breast cancer subtype that represents up to 15% of all breast cancers. Compared to Invasive Breast Carcinoma of No Special Type (IBC-NST), ILCs exhibit poorer long-term outcome and a unique pattern of metastasis. Despite these differences, the systematic discovery of robust prognostic biomarkers and therapeutically actionable molecular pathways in ILC remains limited.

METHODS

Pathway-centric multivariable models using statistical machine learning were developed and tested in seven retrospective clinico-genomic cohorts (n = 996). Further external validation was performed using a new RNA-Seq clinical cohort of aggressive ILCs (n = 48).

RESULTS AND CONCLUSIONS

mRNA dysregulation scores of 25 pathways were strongly prognostic in ILC (FDR-adjusted P < 0.05). Of these, three pathways including Cell-cell communication, Innate immune system and Smooth muscle contraction were also independent predictors of chemotherapy response. To aggregate these findings, a multivariable machine learning predictor called PSILC was developed and successfully validated for predicting overall and metastasis-free survival in ILC. Integration of PSILC with CRISPR-Cas9 screening data from breast cancer cell lines revealed 16 candidate therapeutic targets that were synthetic lethal with high-risk ILCs. This study provides interpretable prognostic and predictive biomarkers of ILC which could serve as the starting points for targeted drug discovery for this disease.

Tumor-Infiltrating Lymphocytes and PD-L1 Expression in Pleomorphic Lobular Breast Carcinoma

BACKGROUND

The prognostic and predictive role of stromal tumor-infiltrating lymphocytes (sTILs) is undetermined in pleomorphic invasive lobular cancer (pILC). The same applies for the expression of PD-1/PD-L1 in this rare breast cancer subtype. Here, we aimed to investigate the expression of sTILs and analyze the PD-L1 expression levels in pILC.

METHODS

Archival tissues from sixty-six patients with pILC were collected. The sTIL density was scored as a percentage of tumor area using the following cut-offs: 0%; <5%; 5-9%; and 10-50%. The PD-L1 expression was analyzed using IHC on formalin-fixed, paraffin-embedded tissue sections using SP142 and 22C3 antibodies.

RESULTS

A total of 82% of the sixty-six patients were hormone receptor positive and 8% of cases were triple negative (TN), while 10% showed human epidermal growth factor receptor 2 (HER2) amplification. sTILs (≥1%) were present in 64% of the study population. Using the SP142 antibody, 36% of tumors demonstrated a positive PD-L1 score of ≥1%, and using the 22C3 antibody, 28% had a positive PD-L1 score of ≥1. There was no correlation between sTILs or PD-L1 expression and tumor size, tumor grade, nodal status, expression of estrogen receptor (ER), or amplification of HER2. Our data did not show any difference in survival between the three molecular subtypes of pILC with respect to sTILs and PD-L1 expression.

CONCLUSION

This study shows that pILCs show some degree of sTILs and PD-L1 expression; however, this was not associated with a survival improvement. Additional large trials are needed to understand immune infiltration in lobular cancer, especially in the pleomorphic subtype.

Genomic assays for lobular breast carcinoma

BACKGROUND

One of the current challenges in breast cancer is the appropriate treatment of invasive lobular breast cancer (ILC) and defining the high-risk group within ILC. The biological character of ILC typically translates to a good prognosis, however, several studies have indicated that the long-term prognosis is worse than for patients diagnosed with the more commonly invasive ductal carcinoma. Many genomic tests are now available to determine whether those patients are at high risk (HR) and enable tailored treatment. Unfortunately, most of the studies in which these genomic tests have been evaluated entail retrospective analysis of a prospective trial.

AIM

This review focuses on the validation of the available genomic assays based on trials performed in ILC patients, where in some instances, the various subtypes of ILC (classical, pleomorphic, and non-classic type) were taken into account.

RESULTS

Using Oncotype DX in retrospective studies, only 1.3%-8% of ILC tumors were categorized as HR tumors. For MammaPrint, 24% of patients were classified as HR, which was associated with poor outcome. In a recent sub-analysis of the MINDACT study comprising 487 ILC patients, 16.2% were high genomic risk. EndoPredict, Prosigna Breast Cancer Prognostic Gene Signature Assay, and the Breast Cancer Index have been validated in patients receiving only endocrine treatment.

CONCLUSION

Although ILC accounts for the second most common breast cancer subtype in women, none of these tests encompass tumor morphology in their algorithms. Prospective studies on ILC with genomic assays are warranted given the various subtypes of and treatment options for this underestimated, but frequently occurring cancer.

RELEVANCE FOR PATIENTS

Genomic assays can be employed in ILC patients to predict the risk of recurrence and identify those patients who might benefit from chemotherapy in addition to their standard treatment regimen.

Biomarker profile of invasive lobular carcinoma: pleomorphic versus classic subtypes, clinicopathological characteristics and prognosis analyses

PURPOSE

To compare the clinicopathologic features and prognosis of pleomorphic invasive lobular carcinoma (P-ILC) and classic ILC (C-ILC) according to the biomarker profile.

METHODS

A total of 667 C-ILCs and 133 P-ILCs between 2011 and 2021 were included. Clinicopathologic features and stromal tumor-infiltrating lymphocytes (sTILs) status were evaluated. P-ILCs were divided into subtypes based on ER/PR and HER2 expression. The overall survival and disease-free survival (DFS) of patients were compared among matched P-ILCs, C-ILCs, and invasive ductal carcinomas (IDCs) with biomarker subtypes.

RESULTS

Compared to C-ILCs, P-ILCs had greater tumor sizes and stages, fewer ER-positive, more HER2-positive, triple negative (TN), and Ki-67 > 20% tumors (P < 0.05). P-ILCs were subdivided into ER+ (63.1%), HER2+ (21.1%) and TN (15.8%). ER+ P-ILCs were mainly showed trabecular and solid growth patterns. Apocrine and solid features were more strongly associated with HER2+ P-ILCs and TN-P-ILCs, respectively. The prognosis of each biomarker group (ER+, HER2+ and TN) differed by subtype. The P-ILC biomarker subtypes had worse prognosis than the same subtypes in the IDC group, while there was no difference between the P-ILC and the C-ILC counterparts. Solid variants of P-ILC had the worst prognosis. Bone was the most common metastatic site in ER+ P-ILCs and TN-P-ILCs. HER2+ P-ILCs tended to metastasize to the brain and liver. DFS of HER2+ P-ILCs and TN-P-ILCs were worse than that of ER+ P-ILCs. Lacking lobular carcinoma in situ and sTILs ≤ 10% were associated with worse survival of ER+ P-ILCs and TN-P-ILCs, respectively. For HER2+ P-ILCs, Ki-67 > 20% and sTILs ≤ 10% were significant factors for lower DFS.

CONCLUSION

P-ILCs is an aggressive subtype of ILCs. Analyzing the prognostic factors of P-ILCs with heterogeneous morphological and biomarker characteristics is helpful for creating an individualized treatment.

Survival Outcomes in Invasive Lobular Carcinoma Compared to Oestrogen Receptor-Positive Invasive Ductal Carcinoma

Invasive lobular breast cancer (ILC) accounts for 10-15% of breast cancers and has distinct characteristics compared with the more common invasive ductal carcinoma (IDC). Studies have shown that ILC may be less sensitive to chemotherapy than IDC, with lower rates of complete pathological response after neo-adjuvant chemotherapy, but it is not clear how this affects long-term survival. Patients at Guy's and St Thomas' NHS Foundation Trust between 1975 and 2016 diagnosed with ER+ IDC or ER+ ILC were eligible for inclusion. Kaplan-Meier plots and Cox proportional-hazards regression models were used for analysis. There was no difference in overall survival comparing ER+ ILC to ER+ IDC (OR: 0.94, 95% CI: 0.83, 1.04) with a median follow-up time of 8.3 years compared to 8.4 years in IDC. However, ER+HER2- ILC had worse survival compared to ER+HER2- IDC in those that received chemotherapy (OR: 1.46, 95% CI: 1.06, 2.01). Here, median follow-up time was 7.0 years in ILC compared to 8.1 years in IDC. These results indicate worse overall survival after chemotherapy (neo-adjuvant and adjuvant) in ILC compared to ER+HER2- IDC even when correcting for tumour grade, age, size, and nodal involvement, but validation is needed in a larger study population.

Comprehensive Review of Molecular Mechanisms and Clinical Features of Invasive Lobular Cancer

Invasive lobular carcinoma (ILC) accounts for 10% to 15% of breast cancers in the United States, 80% of which are estrogen receptor (ER)-positive, with an unusual metastatic pattern of spread to sites such as the serosa, meninges, and ovaries, among others. Lobular cancer presents significant challenges in detection and clinical management given its multifocality and multicentricity at presentation. Despite the unique features of ILC, it is often lumped with hormone receptor-positive invasive ductal cancers (IDC); consequently, ILC screening, treatment, and follow-up strategies are largely based on data from IDC. Despite both being treated as ER-positive breast cancer, querying the Cancer Genome Atlas database shows distinctive molecular aberrations in ILC compared with IDC, such as E-cadherin loss (66% vs. 3%), FOXA1 mutations (7% vs. 2%), and GATA3 mutations (5% vs. 20%). Moreover, compared with patients with IDC, patients with ILC are less likely to undergo breast-conserving surgery, with lower rates of complete response following therapy as these tumors are less chemosensitive. Taken together, this suggests that ILC is biologically distinct, which may influence tumorigenesis and therapeutic strategies. Long-term survival and clinical outcomes in patients with ILC are worse than in stage- and grade-matched patients with IDC; therefore, nuanced criteria are needed to better define treatment goals and protocols tailored to ILC's unique biology. This comprehensive review highlights the histologic and clinicopathologic features that distinguish ILC from IDC, with an in-depth discussion of ILC's molecular alterations and biomarkers, clinical trials and treatment strategies, and future targets for therapy. IMPLICATIONS FOR PRACTICE: The majority of invasive lobular breast cancers (ILCs) are hormone receptor (HR)-positive and low grade. Clinically, ILC is treated similar to HR-positive invasive ductal cancer (IDC). However, ILC differs distinctly from IDC in its clinicopathologic characteristics and molecular alterations. ILC also differs in response to systemic therapy, with studies showing ILC as less sensitive to chemotherapy. Patients with ILC have worse clinical outcomes with late recurrences. Despite these differences, clinical trials treat HR-positive breast cancers as a single disease, and there is an unmet need for studies addressing the unique challenges faced by patients diagnosed with ILC.

Invasive pleomorphic lobular carcinoma of the breast with multiple metastases: A case report

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Invasive Pleomorphic Lobular Carcinoma(IPLC) accounts for less than 1% of breast cancer.

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This paper reports a case of IPLC with multiple metastases and gives review literature.

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The patient’s general condition improved after our specific treatment options, which has a certain reference for the treatment of this kind of patients in the future.

Introduction and importance

IPLC (Invasive Pleomorphic Lobular Carcinoma) accounts for less than 1% of breast cancer. To the best of our knowledge, this is one of the few reported cases in the IPLC with multiple metastases. The patient's general condition got improved after our treatment, which has a certain reference for the treatment of this kind of patient in the future.

Case presentation

A 42-year-old female with IPLC and multiple metastases. The IPLC malignant cells were positive for p120 (cytoplasmic) and human epidermal growth factor receptor 2, negative for estrogen receptor, progesterone receptor, and E-cadherin. There were nodular enhancement foci in the liver, which are considered the metastatic lesions of the breast, and the liver function was abnormal. Multiple metastatic lesions of the vertebral body, appendage of the whole spine, and sternum. And C7, T1, and T9 vertebrae showed compression fractures.

Clinical discussion

IPLC has systemic metastasis which molecular typing by immunohistochemistry is HER-2 overexpression can choose chemotherapy combined with targeted therapy to prolong the survival time and improve the quality of life of patients. The patient was followed up.

Conclusions

This paper reports a case of IPLC with multiple metastases and gives review literature. Our treatment of the patient can be a reference for other clinicians.

Deep learning-enabled breast cancer hormonal receptor status determination from base-level H&E stains

For newly diagnosed breast cancer, estrogen receptor status (ERS) is a key molecular marker used for prognosis and treatment decisions. During clinical management, ERS is determined by pathologists from immunohistochemistry (IHC) staining of biopsied tissue for the targeted receptor, which highlights the presence of cellular surface antigens. This is an expensive, time-consuming process which introduces discordance in results due to variability in IHC preparation and pathologist subjectivity. In contrast, hematoxylin and eosin (H&E) staining—which highlights cellular morphology—is quick, less expensive, and less variable in preparation. Here we show that machine learning can determine molecular marker status, as assessed by hormone receptors, directly from cellular morphology. We develop a multiple instance learning-based deep neural network that determines ERS from H&E-stained whole slide images (WSI). Our algorithm—trained strictly with WSI-level annotations—is accurate on a varied, multi-country dataset of 3,474 patients, achieving an area under the curve (AUC) of 0.92 for sensitivity and specificity. Our approach has the potential to augment clinicians’ capabilities in cancer prognosis and theragnosis by harnessing biological signals imperceptible to the human eye.

Determination of estrogen receptor status (ERS) in breast cancer tissue requires immunohistochemistry, which is sensitive to the vagaries of sample processing and the subjectivity of pathologists. Here the authors present a deep learning model that determines ERS from H&E stained tissue, which could improve oncology decisions in under-resourced settings.

Cell-cell adhesion and 3D matrix confinement determine jamming transitions in breast cancer invasion

Plasticity of cancer invasion and metastasis depends on the ability of cancer cells to switch between collective and single-cell dissemination, controlled by cadherin-mediated cell-cell junctions. In clinical samples, E-cadherin-expressing and -deficient tumours both invade collectively and metastasize equally, implicating additional mechanisms controlling cell-cell cooperation and individualization. Here, using spatially defined organotypic culture, intravital microscopy of mammary tumours in mice and in silico modelling, we identify cell density regulation by three-dimensional tissue boundaries to physically control collective movement irrespective of the composition and stability of cell-cell junctions. Deregulation of adherens junctions by downregulation of E-cadherin and p120-catenin resulted in a transition from coordinated to uncoordinated collective movement along extracellular boundaries, whereas single-cell escape depended on locally free tissue space. These results indicate that cadherins and extracellular matrix confinement cooperate to determine unjamming transitions and stepwise epithelial fluidization towards, ultimately, cell individualization.

Mitotic score and pleomorphic histology in invasive lobular carcinoma of the breast: impact on disease-free survival

PURPOSE

Pleomorphic invasive lobular carcinoma (ILC) has long been thought to have worse outcomes than classic ILC and is therefore often treated with chemotherapy. However, recent data question the utility of the pleomorphic designation, as the poor outcomes seen may be related to other associated high-risk features. Importantly, mitotic count may better define a subset of ILC with high risk of recurrence. We sought to determine the impact of pleomorphic histology versus mitotic count on disease-free survival (DFS) in pure ILC. Additionally, we evaluated whether pleomorphic histology was associated with receipt of chemotherapy when adjusting for other factors.

METHODS

We analyzed a cohort of 475 patients with stage I-III pure ILC. We used Kaplan-Meier estimates, and Cox proportional hazards and logistic regression for multivariate analyses. Pleomorphic histology was confirmed by central pathology review.

RESULTS

In a multivariate model, pleomorphic histology was not associated with reduced DFS. Only mitotic score, receptor subtype, and pathologic stage were independently and significantly associated with DFS. Patients with pleomorphic ILC were significantly more likely to receive chemotherapy than patients with classic ILC (adjusted odds ratio 2.96, p = 0.026).

CONCLUSIONS

The pleomorphic designation in ILC does not have clinical utility and should not be used to determine therapy. Rather, mitotic count identified clear prognostic groups in this cohort of pure ILC.

Intravital microscopy of collective invasion plasticity in breast cancer

Cancer invasion programs are adaptive by switching between metastatic collective and single-cell dissemination; however, current intravital microscopy models for epithelial cancer in mice fail to reliably recreate such invasion plasticity. Using microimplantation of breast cancer spheroids into the murine mammary fat pad and live-cell monitoring, we show microenvironmental conditions and cytoskeletal adaptation during collective to single-cell transition in vivo E-cadherin-expressing 4T1 and E-cadherin-negative MMT tumors both initiated collective invasion along stromal structures, reflecting invasion patterns in 3D organotypic culture and human primary ductal and lobular carcinoma. Collectively invading cells developed weakly oscillatory actin dynamics, yet provided zones for single-cell transitions with accentuated, more chaotic actin fluctuations. This identifies collective invasion in vivo as a dynamic niche and efficient source for single-cell release.

Invasive Lobular Breast Carcinoma: Pleomorphic Versus Classical Subtype, Associations and Prognosis

BACKGROUND

Invasive pleomorphic lobular carcinoma (IPLC) has been associated with a worse prognosis compared with classic invasive lobular carcinoma (cILC); however, studies are small and conflicting. We seek to examine the prognosis of women with IPLC compared with cILC.

METHODS

A retrospective review of women with breast cancer at a single institution from 2003 to 2012 identified 193 women with invasive lobular carcinoma (ILC). IPLC was defined as ILC with a pathological description of primarily pleomorphic features and Nottingham histological grade score of 7, 8, or 9 or overall grade of 3 or mixed classic/pleomorphic features and overall grade of 3. All others were designated cILCs. Clinicopathologic variables, progression-free survival (PFS), per STEEP criteria, and overall survival (OS), using all-cause mortality, were examined in both groups.

RESULTS

Of the 193 women, 46 (24%) had IPLC and 147 (76%) had cILC. The IPLC group had significantly higher stage at diagnosis and more Hispanic women, but there were no differences in other clinicopathologic features or treatment. Median follow-up was 57 months (0.1-155 months). In univariate analysis, IPLC was associated with worse PFS (log-rank P = .09, Wilcoxon P = .01) but no significant differences in OS (log-rank P = .20, Wilcoxon P = .16). In multivariate models adjusting for stage, IPLC was not significantly associated with PFS (hazard ratio [HR] 1.43; 95% confidence interval [CI], 0.73-2.79; P = .30) or OS (HR 1.52; 95% CI, 0.58-4.01; P = .40).

CONCLUSIONS

IPLC was initially associated with worse PFS, but this was attenuated after adjustment for cancer stage, and there were no differences in OS.

Pleomorphic lobular carcinoma of the breast: a comparison of cytopathological features with other lobular carcinoma variants

OBJECTIVE

Pleomorphic lobular carcinoma (PLC) is a subtype of breast cancer with unique morphological features, but it remains controversial whether PLC should be considered an independent disease entity. The aim of this study was to illustrate cytopathological characteristics of PLC in comparison with other lobular carcinoma variants.

METHODS

We investigated clinicopathological features of PLC (n = 11) compared with those of other variants of invasive lobular carcinoma (ILC, non-PLC) (n = 32). Histological variants of the non-PLC group consisted of classic (n = 25), solid (n = 2), alveolar (n = 1) and a tubulolobular type (n = 4). A review of cytological reports and fine needle aspiration (FNA) smear samples was performed for the PLC (n = 9) and non-PLC (n = 27) groups.

RESULTS

Patients with PLC were older, and had a higher nuclear grade and a higher incidence of axillary lymph node metastasis and triple negative phenotype than non-PLC patients (P = 0.007, P < 0.001, P = 0.02 and P < 0.001, respectively). Cytological findings in PLC included medium- to large-sized nuclei, prominent nucleoli, a moderate-to-severe degree of pleomorphism, apocrine change and background necrosis, none of which were evident in the smears of the non-PLC group (P < 0.001, P = 0.002, P < 0.001, P < 0.001, and P = 0.03, respectively). Despite these differences, patients with PLC and non-PLC showed similar clinical outcomes in our follow-up period.

CONCLUSIONS

Based on our results, a cytological diagnosis of PLC should be proposed if there are moderate- to large-sized nuclei, prominent nucleoli, a moderate-to severe degree of nuclear pleomorphism, apocrine change and necrosis in the background in FNA biopsy samples.

Expression of cancer-associated fibroblast-related proteins differs between invasive lobular carcinoma and invasive ductal carcinoma

Cancer-associated fibroblasts (CAFs) are classified into various functional subtypes such as fibroblast activation protein-α (FAP-α), fibroblast specific protein-1 (FSP-1), platelet-derived growth factor receptor-α (PDGFR-α), and PDGFR-β. In this study, we compared the expression of CAF-related proteins in invasive lobular carcinoma (ILC) with those in invasive carcinoma of no special type (NST) and assessed the implications of the differences observed. Using tissue microarrays of 104 ILC and 524 invasive carcinoma (NST) cases, immunohistochemistry for CAF-related proteins [podoplanin, prolyl 4-hydroxylase, FAP-α, FSP-1/S100A4, PDGFR-α, PDGFR-β, and chondroitin sulfate proteoglycan (NG2)] was conducted. In invasive carcinoma (NST), tumor cells expressed a high level of PDGFR-α, whereas ILC tumor cells expressed high levels of podoplanin, prolyl 4-hydroxylase, FAP-α, and FSP-1/S100A4. In stromal cells of invasive carcinoma (NST), high expression levels of prolyl 4-hydroxylase, PDGFR-α, and NG2 were observed, whereas ILC stromal cells expressed high levels of FAP-α, FSP-1/S100A4, and PDGFR-β. In ILC, tumoral FSP-1/S100A4 positivity was associated with higher Ki-67 labeling index (p = 0.010) and non-luminal A type cancer (p = 0.014). Stromal PDGFR-α positivity was associated with lymph node metastasis (p = 0.011). On survival analysis of entire cases, tumoral FSP-1/S100A4 positivity (p = 0.002), stromal podoplanin positivity (p = 0.041), and stromal FSP-1/S100A4 negativity (p = 0.041) were associated with shorter disease-free survival; only tumoral FSP-1/S100A4 positivity (p = 0.044) was associated with shorter overall survival. In ILC, the expression of FAP-α and FSP-1/S100A4 was higher in both tumor and stromal cells than that observed in invasive carcinoma (NST). These results indicate that CAFs are a potential target in ILC treatment.

Invasive Pleomorphic Lobular Carcinoma of the Breast: Pathologic, Clinical, and Therapeutic Considerations

Pleomorphic lobular carcinoma is an uncommon form of breast cancer and a subtype of invasive lobular carcinoma. It has unique histopathologic features that translate to a more aggressive phenotype with an associated poor prognosis. Unlike classical invasive lobular carcinoma, it can lose estrogen and progesterone receptor expression and demonstrate HER-2/neu amplification. It remains to be determined, however, whether the pleomorphic histology independently predicts a worse outcome or whether other known associated negative prognostic factors such as larger tumor size, increased metastatic disease, and associated worse molecular subtypes commonly present in pleomorphic carcinoma account for the poor prognosis. Here we present an updated review of the unique pathologic and clinical features of pleomorphic lobular carcinoma needed to guide management for women with this subtype of cancer.