Lobular breast cancer series: imaging

Variation in surgical treatment by body mass index in patients with invasive lobular carcinoma of the breast

PURPOSE

Patients with invasive lobular carcinoma (ILC) face high rates of positive margins and completion mastectomy, which can be improved with the use of specific techniques, such as oncoplastic surgery. However, prior studies have shown that type of breast cancer surgery performed is also associated with patient factors such as elevated body mass index (BMI). Thus, this study investigates whether BMI impacts the type of surgical interventions in patients with ILC.

METHODS

A retrospective analysis of 705 patients with stage I-III ILC from an institutional database was conducted. Patients were stratified by BMI (underweight, normal weight, overweight, obese). Pearson's Chi-square, ANOVA, and multivariable logistic regression were used to evaluate the relationship between BMI and surgical procedures.

RESULTS

Breast-conserving surgery (BCS) was the initial operation in 60% of patients, with no significant difference by BMI. Among those undergoing BCS, patients with obese BMI were significantly more likely to undergo oncoplastic surgery (46.9% vs. 7.7%, 37.3%, and 33.6% for underweight, normal, and overweight, respectively, p = 0.032). Obese BMI patients undergoing mastectomy were less likely to have reconstruction compared to those with underweight, normal weight, and overweight BMI (44.2% vs. 50%, 71.1%, and 64.1%, p = 0.002).

CONCLUSION

Overweight/obese BMI patients with ILC underwent different surgical interventions compared to those with lower BMI. While initial BCS rates were similar, overweight/obese patients had higher oncoplastic surgery rates in BCS and lower reconstruction rates in mastectomy. Further research is needed to understand BMI's impact on surgical decisions and outcomes in ILC.

E-Cadherin Mutational Landscape and Outcomes in Breast Invasive Lobular Carcinoma

Invasive lobular carcinomas (ILC) are characterized by the loss of E-cadherin expression and CDH1 gene inactivation. Diagnostic reproducibility for this tumor type is currently suboptimal and could be improved by a better understanding of its histomolecular and clinical heterogeneity. We have analyzed the relationship between the presence, type, or position of CDH1 mutations, E-cadherin expression, and clinicopathological features (including outcome) in a retrospective series of 251 primary ILC with a long follow-up (median: 9.5 years). The mutational status of E-cadherin gene (CDH1) was determined by RNA sequencing from frozen tumor samples. E-cadherin immunohistochemistry (IHC) was performed with antibodies directed against the intracellular domain (clone 4A2C7) and the extracellular domain (clone NCH38). IHC expression of p120 and β-catenin was also assessed in E-cadherin diffusely positive cases. Three major patterns of E-cadherin membrane expression were identified by IHC, with good agreement between the 2 clones (overall concordance: 83.8%, Kappa 0.67): null/focal expression (≤10%) (72.8% of cases for 4A2C7 and 83.8% for NCH38), heterogeneous expression (11%-89%) (19.2% of cases for 4A2C7 and 6.9% for NCH38), and diffuse expression (≥90%) (8% of cases for 4A2C7 and 9.3% for NCH38). E-cadherin membranous expression, when present, was abnormal (incomplete labeling and/or reduced intensity). ILC with diffuse E-cadherin expression showed abnormal β-catenin or p120-catenin staining in 21% of cases. Interestingly, these cases with diffusely expressed E-cadherin had a CDH1 mutation rate as high as the E-cadherin null/focal cases (∼70%) but were enriched in nontruncating mutations. Regarding CDH1 mutation location, intracytoplasmic domain mutations correlated with a divergent E-cadherin IHC phenotype between the 2 antibodies (4A2C7 ≤ 10%/NCH38 ≥ 10%). Clinico-pathological correlation analyses found that stromal amount (inversely correlated with tumor cellularity) and tumor-infiltrating lymphocytes were less abundant in ILC with E-cadherin null/focal cases. In addition, CDH1 truncating mutations were associated with radiohistologic size discordance and were identified in multivariate survival analysis as an independent poor prognosis factor in terms of metastasis risk and breast cancer-related mortality. Overall, our study highlights the importance of the precise mutational status of CDH1 in the clinical, radiological, histologic, and phenotypic expression of lobular carcinomas. These findings should be taken into account in future attempts to improve diagnostic criteria or methods for ILC, as well as for clinicobiological studies dedicated to this tumor type.

Characteristics and clinical outcomes of breast cancer in young BRCA carriers according to tumor histology

BACKGROUND

Young women with breast cancer (BC) have an increased chance of carrying germline BRCA pathogenic variants (PVs). Limited data exist on the prognostic impact of tumor histology (i.e. ductal versus lobular) in hereditary breast cancer.

METHODS

This multicenter retrospective cohort study included women aged ≤40 years with early-stage breast cancer diagnosed between January 2000 and December 2020 and known to carry germline PVs in BRCA1/2. Histology was locally assessed in each center. The Kaplan-Meier method and Cox regression analysis were used to assess disease-free survival and overall survival.

RESULTS

Of 4628 patients included from 78 centers worldwide, 3969 (86%) had pure ductal, 135 (3%) pure lobular, and 524 (11%) other histologies. Compared with ductal tumors, lobular tumors were more often grade 1/2 (57.7% versus 22.1%), stage III (29.6% versus 18.5%), and luminal A-like (42.2% versus 12.2%). Lobular tumors were more often associated with BRCA2 PVs (71.1% BRCA2), while ductal tumors were more often associated with BRCA1 PVs (65.7% BRCA1). Patients with lobular tumors more often had mastectomy (68.9% versus 58.3%), and less often received chemotherapy (83.7% versus 92.9%). With a median follow-up of 7.8 years, no significant differences were observed in disease-free survival (adjusted hazard ratio 1.01, 95% confidence interval 0.74-1.37) or overall survival (hazard ratio 0.96, 95% confidence interval 0.62-1.50) between patients with ductal versus lobular tumors. No significant survival differences were observed according to specific BRCA gene, breast cancer subtype, or body mass index.

CONCLUSIONS

In this large global cohort of young BRCA carriers with breast cancer, the incidence of pure lobular histology was low and associated with higher disease stage at diagnosis, luminal-like disease and BRCA2 PVs. Histology did not appear to impact prognosis.

Surveillance Strategies After Primary Treatment for Patients with Invasive Lobular Carcinoma of the Breast: Method of Local Recurrence Detection After Breast-Conserving Surgery

BACKGROUND

Invasive lobular carcinoma (ILC) is the second most common subtype of breast cancer. Although mammography is known to have low sensitivity for ILC, there are no data to guide the optimal surveillance after treatment. We explored surveillance strategies after breast-conserving surgery (BCS) for ILC and determined the proportion of imaging-detected recurrences versus interval cancers.

METHODS

From an institutional database of 813 women, we retrospectively identified patients who underwent BCS for stage I-III ILC and subsequently had a recurrence. We categorized patients by surveillance strategy and determined the modality of recurrence detection. Interval cancer rates for local recurrences were compared across surveillance strategies using the Chi-square test. We evaluated overall survival with the log-rank test and a Cox proportional hazards model.

RESULTS

We included 58 patients with ILC who had a recurrence after BCS. Of these, 22 (37.9%) had local recurrence, 27 (46.6%) had distant recurrence, and 9 (15.5%) had both local and distant recurrence. Most patients underwent routine mammographic surveillance (65.2%), with 19.6% having supplemental breast magnetic resonance imaging (MRI) and 15.2% having no surveillance. The interval cancer rate was significantly higher in the mammographic surveillance group compared with the MRI surveillance group (61.9% vs. 16.7%; p < 0.001).

CONCLUSION

In this study of patients with recurrence after BCS for primary treatment of stage I-III ILC, we found that most local recurrences were not detected by surveillance mammography. These data support further investigation of supplemental imaging beyond mammography specifically for patients with ILC who undergo BCS.

Is staging breast magnetic resonance imaging for invasive lobular carcinoma worthwhile?

BACKGROUND

Invasive lobular carcinoma (ILC) is challenging to stage accurately using mammography (MG) and ultrasound (US) with undiagnosed ipsilateral and contralateral cancer resulting in poor patient outcomes including return to surgery. Our institution employs routine staging breast MRI in ILC for this reason. However, increased time for further imaging/biopsies contributes to patient anxiety and potentially delays definite management. We aimed to quantify the frequency of staging MRI-detected additional lesions requiring biopsy or follow-up, the added cancer detection rate and MRI prompted change in surgical management.

METHODS

An observational study on staging breast MRI for newly diagnosed ILC at a tertiary Western Australian hospital from January 2019 to August 2022. Standardized 3T MRI protocol was performed, double read by unblinded fellowship-trained radiologists. Histopathology from biopsy, surgery, or first annual surveillance was the reference standard for additional MRI-detected lesions.

RESULTS

One hundred ten MRI studies demonstrated 49 (45%) patients had at least one additional clinically significant MRI-detected lesion. Thirty-one patients had an additional ipsilateral lesion detected, of which 18 (58%) proved malignant; 14 (45%) multifocal and 4 (13%) multicentric ILC. Additional work-up of MRI-detected lesions averaged a 9-day delay to definitive surgery compared to patients with a negative or definitively benign MRI. MRI changed surgical planning in 11 of 110 cases from breast conservation surgery (BCS) to mastectomy and there were two contralateral cancers diagnosed. BCS reoperation rate was 11%.

CONCLUSION

Staging MRI for ILC identifies clinically significant lesions in nearly half of patients, predominantly ipsilateral multifocal disease, without significant delay to definitive surgery.

Preoperative breast MR imaging influences surgical management in patients with invasive lobular carcinoma

INTRODUCTION

The purpose of the study is to assess the role of preoperative magnetic resonance (MR) imaging on the surgical management of invasive lobular carcinoma (ILC) and to evaluate whether breast density and background parenchymal enhancement (BPE) influence surgical treatment.

METHODS

This retrospective study was conducted on 56 patients who were diagnosed with ILC between 2014 and 2020. All patients had mammogram and ultrasound. Preoperative MRI was available in 34 patients. Age, menopausal status, breast density, BPE, multifocality/multicentricity and surgical treatment were collected.

RESULTS

Mean pathological tumour size was 36.4 mm (range 5-140 mm). Dense breasts had larger tumours compared to non-dense breasts (P = 0.072). Of the 34 patients with MRI, 6 opted for mastectomy. Of the remaining 28 cases, MRI findings upgraded surgery to mastectomy in 54% (15/28) because mammogram/ultrasound underestimated tumour extent in 25% (7/28), or multifocal/multicentric disease was identified in 29% (8/28). Tumour size was underestimated by MRI in 7% (2/28). In the non-MRI subgroup, 64% (14/22) of patients underwent breast-conserving surgery, but 29% of them (4/14) required a second-stage mastectomy due to extensive margin involvement. There was no difference in mastectomy rate between patients with MRI (62%) and without MRI (55%) (P = 0.061). Tumour size correlation between MRI and histopathology demonstrated an excellent intraclass correlation coefficient (P < 0.001). Surgical treatment recommendation was not significantly impacted by breast density or BPE.

CONCLUSION

Breast MRI improves surgical management of patients with ILC in providing additional diagnostic information often missed with standard imaging modalities, and without increasing mastectomy rate. Surgical treatment is not impacted by breast density or BPE.

Invasive lobular carcinoma of the breast; clinicopathologic profile and response to neoadjuvant chemotherapy over a 15-year period

INTRODUCTION

Invasive lobular carcinoma (ILC) accounts for 5-15% of invasive breast cancers. Typical ILC is oestrogen receptor (ER) positive and human epidermal growth factor receptor 2 (HER2) negative. Atypical biomarker profiles (ER- and HER2+, ER+ and HER2+ or triple negative) appear to differ from typical ILCs. This study compared subtypes of ILC in terms of clinical and pathological parameters, and response to neoadjuvant chemotherapy (NACT) according to biomarker profile.

METHODS

All patients with ILC treated in a single centre from January 2005 to December 2020 were identified from a prospectively maintained database. Clinicopathologic and outcome data was collected and analysed according to tumour biomarker profile.

RESULTS

A total of 582 patients with ILC were treated. Typical ILC was observed in 89.2% (n = 519) and atypical in 10.8% (n = 63). Atypical ILCs were of a higher grade (35% grade 3 vs 9.6% grade 3, p < 0.001). A larger proportion of atypical ILC received NACT (31.7% vs 6.9% p < 0.001). Atypical ILCs showed a greater response to NACT (mean RCB (Residual Cancer Burden Score) 2.46 vs mean RCB 3.41, p = 0.0365), and higher pathological complete response rates (15% vs 0% p = 0.017). Despite this, overall 5-year disease-free survival (DFS) was higher in patients with typical ILC (91% vs 83%, p = 0.001).

CONCLUSIONS

Atypical ILCs have distinct characteristics. They are more frequently of a higher grade and demonstrate a superior response to NACT. Despite the latter, atypical ILCs have a worse 5-year DFS which should be taken into consideration in terms of prognostication and may assist patient selection for NACT.

Special Types of Breast Cancer: Clinical Behavior and Radiological Appearance

Breast cancer is a complex disease that includes entities with different characteristics, behaviors, and responses to treatment. Breast cancers are categorized into subgroups based on histological type and grade, and these subgroups affect clinical presentation and oncological outcomes. The subgroup of "special types" encompasses all those breast cancers with insufficient features to belong to the subgroup "invasive ductal carcinoma not otherwise specified". These cancers account for around 25% of all cases, some of them having a relatively good prognosis despite high histological grade. The purpose of this paper is to review and illustrate the radiological appearance of each special type, highlighting insights and pitfalls to guide breast radiologists in their routine work.

The Challenges of Lobular Carcinomas from a Surgeon's Point of View

Invasive lobular breast cancer (ILC) presents unique challenges and considerations in the realm of surgical management. Characterized by its distinct histological features, including the loss of E-cadherin expression and dys-cohesive growth pattern, ILC often poses diagnostic and therapeutic dilemmas for clinicians. This abstract explores the surgical landscape of ILC, focusing on its epidemiology, clinical presentation, diagnostic modalities, and surgical interventions. Emphasizing the importance of individualized treatment strategies, this narrative delves into the nuances of surgical decision-making, including the role of breast-conserving surgery versus mastectomy, axillary staging, and the significance of margin status. Additionally, advancements in surgical techniques, such as oncoplastic approaches and sentinel lymph node biopsy, are examined in the context of optimizing oncologic outcomes and preserving cosmesis. Through a comprehensive review of current literature and clinical guidelines, this overview aims to provide a nuanced understanding of the surgical considerations inherent to the management of invasive lobular breast cancer.

Reporting on invasive lobular breast cancer in clinical trials: a systematic review

Invasive lobular breast cancer (ILC) differs from invasive breast cancer of no special type in many ways. Evidence on treatment efficacy for ILC is, however, lacking. We studied the degree of documentation and representation of ILC in phase III/IV clinical trials for novel breast cancer treatments. Trials were identified on Pubmed and clinicaltrials.gov. Inclusion/exclusion criteria were reviewed for requirements on histological subtype and tumor measurability. Documentation of ILC was assessed and ILC inclusion rate, central pathology and subgroup analyses were evaluated. Inclusion restrictions concerning tumor measurability were found in 39/93 manuscripts. Inclusion rates for ILC were documented in 13/93 manuscripts and varied between 2.0 and 26.0%. No central pathology for ILC was reported and 3/13 manuscripts had ILC sub-analyses. ILC is largely disregarded in most trials with poor representation and documentation. The current inclusion criteria using RECIST v1.1, fall short in recognizing the unique non-measurable metastatic infiltration of ILC.

Circulating tumor cells in early lobular versus ductal breast cancer and their associations with prognosis

This is a secondary data analysis of the TIPPING study, which included 1,121 patients with stage I-III breast cancer who had enumeration of CTCs (by either CellSearch or immunomagnetic enrichment and flow cytometry [IE/FC]) and disseminated tumor cells (DTCs) at the time of surgical resection between 1999 and 2012. The primary endpoint was mean number of CTCs by histology, taking into account method of detection and treatment type, and evaluation of histology specific prognostic cutpoints. Overall, patients with ILC had significantly higher CTC counts than those with IDC, a finding which persisted in the 382 patients with CTC enumeration by IE/FC method. Additionally, among those with primary surgery, patients with ILC had significantly higher mean CTC counts than those with IDC (mean 2.11 CTCs/mL versus 0.71 CTCs/mL respectively, p < 0.001), which persisted on multivariate analysis. Patients with ILC and CTC-high/DTC-high status trended towards reduced DRFS HR = 9.27, 95% CI 0.95-90.5, p = 0.055) and had significantly decreased BCSS (HR = 10.4, 95% CI 1.07-99.7, P = 0.043) compared with those who were CTC-low/DTC-low. In the IDC group, CTC-high/DTC-high status was not associated with either DRFS or BCSS. In neoadjvuantly treated patients, there was no significant difference in CTC counts in the ILC group versus the IDC group (mean 0.89 CTCs/mL versus 1.06 CTCs/mL respectively, p = 0.82). Our findings contribute to the limited literature on CTCs and DTCs in ILC, and suggest that clinical utility and optimal thresholds for CTC and DTC assays may differ by histologic subtype in early-stage breast cancer.

MRI of the Lactating Breast

The breasts undergo marked physiologic changes during lactation that can make conventional imaging evaluation with mammography and US challenging. MRI can be a valuable diagnostic aid to differentiate physiologic and benign processes from malignancy in patients who are lactating. In addition, MRI may allow more accurate delineation of disease involvement than does conventional imaging and assists in locoregional staging, screening of the contralateral breast, assessment of response to neoadjuvant chemotherapy, and surgical planning. Although the American College of Radiology recommends against patients undergoing contrast-enhanced MRI during pregnancy because of fetal safety concerns, contrast-enhanced MRI is safe during lactation. As more women delay childbearing, the incidence of pregnancy-associated breast cancer (PABC) and breast cancer in lactating women beyond the 1st year after pregnancy is increasing. Thus, MRI is increasingly being performed in lactating women for diagnostic evaluation and screening of patients at high risk. PABC is associated with a worse prognosis than that of non-PABCs, with delays in diagnosis contributing to an increased likelihood of advanced-stage disease at diagnosis. Familiarity with the MRI features of the lactating breast and the appearance of various pathologic conditions is essential to avoid diagnostic pitfalls and prevent delays in cancer diagnosis and treatment. The authors review clinical indications for breast MRI during lactation, describe characteristic features of the lactating breast at MRI, and compare MRI features of a spectrum of benign and malignant breast abnormalities. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Chikarmane in this issue.

Differential response to neoadjuvant endocrine therapy for Black/African American and White women in NCDB

PURPOSE

Compared to White women, there are higher mortality rates in Black/African American (BAA) women with hormone receptor-positive breast cancer (HR + BC) which may be partially due to differences in treatment resistance. We assessed factors associated with response to neoadjuvant endocrine therapy (NET).

METHODS

The National Cancer Database (NCDB) was queried for women with clinical stage I-III HR + BC diagnosed 2006-2017 and treated with NET. Univariate and multivariate analyses described associations between the sample, duration of NET, and subsequent treatment response, defined by changes between clinical and pathological staging.

RESULTS

The analytic sample included 9864 White and 1090 BAA women. Compared to White women, BAA women were younger, had more co-morbidities, were higher stage at presentation, and more likely to have > 24 weeks of NET. After excluding those with unknown pT/N/M, 3521 White and 365 BAA women were evaluated for NET response. On multivariate analyses, controlling for age, stage, histology, HR positivity, and duration of NET, BAA women were more likely to downstage to pT0/Tis (OR 3.0, CI 1.2-7.1) and upstage to Stage IV (OR 2.4, CI 1.002-5.6). None of the women downstaged to pT0/Tis presented with clinical stage III disease; only 2 of the women upstaged to Stage IV disease presented with clinical Stage I disease.

CONCLUSION

Independent of NET duration and clinical stage at presentation, BAA women were more likely to experience both complete tumor response and progression to metastatic disease. These results suggest significant heterogeneity in tumor biology and warrant a more nuanced therapeutic approach to HR + BC.

Effect of histological breast cancer subtypes invasive lobular versus non-special type on survival in early intermediate-to-high-risk breast carcinoma: results from the SUCCESS trials

BACKGROUND

Invasive lobular breast carcinomas (ILC) have different histological features compared to non-special type carcinomas (NST), but the effect of histological subtypes on survival is controversial. In this study, we compared clinicopathological characteristics and outcomes between ILC and NST based on a large pooled data set from three adjuvant breast cancer trials (SUCCESS A, B, and C) and investigated a potential differential effect of recurrence risk related to nodal stage on survival.

METHODS

From 2005 to 2017, the large randomized controlled SUCCESS A, B, and C trials enrolled 8190 patients with primary, intermediate-to-high-risk breast carcinoma. All patients received adjuvant chemotherapy, and endocrine and/or HER2-targeted treatment was given where appropriate. Survival outcomes in terms of disease-free survival (DFS), overall survival (OS), breast cancer-specific survival (BCSS), and distant disease-free survival (DDFS) were estimated using the Kaplan-Meier method and analyzed using log-rank tests as well as univariable and adjusted multivariable Cox regression models.

RESULTS

In the SUCCESS trials, 6284 patients had NST and 952 had ILC. The median follow-up time was 64 months. ILC patients were older, more likely to receive mastectomy, and more likely to have larger tumor sizes, lymph node infiltration, hormone receptor-positive, HER2neu-negative, and luminal A-like tumors than NST patients. In the overall cohort, no significant differences between ILC and NST were detectable regarding the four survival endpoints, with hazard ratios obtained in adjusted multivariable cox regressions of 0.96 (95% CI 0.77-1.21, p = 0.743) for DFS, 1.13 (95% CI 0.85-1.50, p = 0.414) for OS, 1.21 (95% CI 0.89-1.66, p = 0.229) for BCSS, and 0.95 (95% CI 0.73-1.24, p = 0.689) for DDFS. However, a differential effect of nodal stage on survival was observed, with better survival for ILC patients with pN0/pN1 tumors and worse survival for ILC patients with pN2/pN3 tumors compared to NST patients.

CONCLUSIONS

Our results revealed that ILC was associated with worse survival compared to NST for patients at high risk of recurrence due to advanced lymph node infiltration. These findings should be taken into account for treatment decisions and monitoring.

Digital mammography and digital breast tomosynthesis for detecting invasive lobular and ductal carcinoma

PURPOSE

Invasive lobular carcinoma (ILC) is a distinct histological subtype of breast cancer that can make early detection with mammography challenging. We compared imaging performance of digital breast tomosynthesis (DBT) to digital mammography (DM) for diagnoses of ILC, invasive ductal carcinoma (IDC), and invasive mixed carcinoma (IMC) in a screening population.

METHODS

We included screening exams (DM; n = 1,715,249 or DBT; n = 414,793) from 2011 to 2018 among 839,801 women in the Breast Cancer Surveillance Consortium. Examinations were followed for one year to ascertain incident ILC, IDC, or IMC. We measured cancer detection rate (CDR) and interval invasive cancer rate/1000 screening examinations for each histological subtype and stratified by breast density and modality. We calculated relative risk (RR) for DM vs. DBT using log-binomial models to adjust for the propensity of receiving DBT vs. DM.

RESULTS

Unadjusted CDR per 1000 mammograms of ILC overall was 0.33 (95%CI: 0.30-0.36) for DM; 0.45 (95%CI: 0.39-0.52) for DBT, and for women with dense breasts- 0.33 (95%CI: 0.29-0.37) for DM and 0.54 (95%CI: 0.43-0.66) for DBT. Similar results were noted for IDC and IMC. Adjusted models showed a significantly increased RR for cancer detection with DBT compared to DM among women with dense breasts for all three histologies (RR; 95%CI: ILC 1.53; 1.09-2.14, IDC 1.21; 1.02-1.44, IMC 1.76; 1.30-2.38), but no significant increase among women with non-dense breasts.

CONCLUSION

DBT was associated with higher CDR for ILC, IDC, and IMC for women with dense breasts. Early detection of ILC with DBT may improve outcomes for this distinct clinical entity.

Histologic tumor type as a determinant of survival in hormone receptor-positive, HER2-negative, pT1-3 invasive ductal and lobular breast cancer

PURPOSE

The aim of the study was to compare the difference in survival between invasive ductal (IDC) and lobular carcinoma (ILC).

METHODS

Data of patients (n = 1843) with a hormone receptor-positive, HER2-negative, pT1-3 IDC or ILC cancer without distant metastasis, treated at the Ghent University Hospital over the time period 2001-2015, were analyzed.

RESULTS

ILC represented 13.9% of the tumors, had a higher percentage of pT3 and pN3 stages than IDC, lymphovascular space invasion (LVSI) was less present and Ki-67 was mostly low. 73.9% of ILCs were grade 2, whereas IDC had more grade 1 and grade 3 tumors. Kaplan-Meier curves and log-rank testing showed a significant worse DFS for ILC with pN ≥ 1 than for their IDC counterpart. In a multivariable Cox regression analysis the histologic tumor type, ductal or lobular, was a determinant of DFS over 120 months (IDC as reference; hazard ratio for ILC 1.77, 95% CI 1.08-2.90) just as the ER Allred score (hazard ratio 0.84, 95% CI 0.78-0.91), LVSI (hazard ratio 1.75, 95% CI 1.12-2.74) and pN3 (hazard ratio 2.29, 95% CI 1.03-5.09). Determinants of OS over ten years were age (hazard ratio 1.05, 95% CI 1.02-1.07), LVSI (hazard ratio 3.62, 95% CI 1.92-6.82) and the ER Allred score (hazard ratio 0.80, 95% CI 0.73-0.89).

CONCLUSION

The histologic tumor type, ductal or lobular, determines DFS in hormone receptor-positive, HER2-negative, pT1-3 breast cancer besides the ER Allred score, LVSI and pN3.

Bright Is Not Always Better: A Pictorial Review of Hyperechoic Malignant Breast Masses

Hyperechogenic breast lesions are a relatively rare finding at breast ultrasonography and are traditionally thought to be benign. However, hyperechogenicity on the ultrasound alone does not provide enough evidence to rule out malignancy completely. We herein reported a short series of nine cases of echogenic malignant breast lesions, which include invasive ductal carcinoma, ductal carcinoma in situ, invasive lobular carcinoma, angiosarcoma, lymphoma, and metastasis to the breast. Echogenic breast lesions should be carefully evaluated and properly categorized based on any other suspicious sonographic characteristics and must be correlated with mammographic findings and clinical history to lower the threshold for biopsy and avoid delay in diagnosis. Hyperechogenicity should not be considered as a characteristically benign feature and should not supersede the less specifically benign features of the same lesion on the other examination.

Defining features of hereditary lobular breast cancer due to CDH1 with magnetic resonance imaging and tumor characteristics

Women with germline pathogenic variants in CDH1, which encodes E-cadherin protein, are at increased lifetime risk of invasive lobular carcinoma (ILC). The associated tumor characteristics of hereditary lobular breast carcinoma (HLBC) in this high-risk population are not well-known. A single-center prospective cohort study was conducted to determine the imaging and pathologic features of HLBC compared to population-based ILC using Surveillance, Epidemiology, and End Results (SEER) data. One hundred fifty-eight women with CDH1 variants were evaluated, of whom 48 (30%) also had an ILC diagnosis. The median age at CDH1 diagnosis was 45 years [interquartile range, IQR 34-57 years] whereas the median age at diagnosis of CDH1 with concomitant ILC (HLBC) was 53 [IQR 45-62] years. Among women with HLBC, 83% (40/48) were identified with CDH1 mutation after diagnosis of ILC. Among 76 women (48%, 76/158) undergoing surveillance for ILC with breast magnetic resonance imaging (MRI), 29% (22/76) had an abnormal MRI result with available biopsy data for comparison. MRI detected ILC in 7 out of 8 biopsy-confirmed cases, corresponding with high sensitivity (88%), specificity (75%), and negative predictive value (98%); however, false-positive and false-discovery rates were elevated also (25% and 68%, respectively). HLBC was most frequently diagnosed at age 40-49 years (44%, 21/48), significantly younger than the common age of diagnosis of ILC in SEER general population data (most frequent age range 60-69 years, 28%; p < 0.001). HLBC tumors were smaller than SEER-documented ILC tumors (median 1.40 vs. 2.00 cm; p = 0.002) and had a higher incidence of background lobular carcinoma in situ (88% vs. 1%; p < 0.001) as well as progesterone receptor positivity (95% vs. 81%, p = 0.032). These findings suggest that HLBC is often detected via conventional screening methods as an early-stage hormone receptor-positive tumor, thus the clinical benefit of intensive screening with MRI may be limited to a subset of women with germline CDH1 variants.

WCRC-25: A novel luminal Invasive Lobular Carcinoma cell line model

Breast cancer is categorized by the molecular and histologic presentation of the tumor, with the major histologic subtypes being No Special Type (NST) and Invasive Lobular Carcinoma (ILC). ILC are characterized by growth in a single file discohesive manner with stromal infiltration attributed to their hallmark pathognomonic loss of E-cadherin ( CDH1 ). Few ILC cell line models are available to researchers. Here we report the successful establishment and characterization of a novel ILC cell line, WCRC-25, from a metastatic pleural effusion from a postmenopausal Caucasian woman with metastatic ILC. WCRC-25 is an ER-negative luminal epithelial ILC cell line with both luminal and Her2-like features. It exhibits anchorage independent growth and haptotactic migration towards Collagen I. Sequencing revealed a CDH1 Q706* truncating mutation, together with mutations in FOXA1, CTCF, BRCA2 and TP53 , which were also seen in a series of metastatic lesions from the patient. Copy number analyses revealed amplification and deletion of genes frequently altered in ILC while optical genome mapping revealed novel structural rearrangements. RNA-seq analysis comparing the primary tumor, metastases and the cell line revealed signatures for cell cycle progression and receptor tyrosine kinase signaling. To assess targetability, we treated WCRC-25 with AZD5363 and Alpelisib confirming WCRC-25 as susceptible to PI3K/AKT signaling inhibition as predicted by our RNA sequencing analysis. In conclusion, we report WCRC-25 as a novel ILC cell line with promise as a valuable research tool to advance our understanding of ILC and its therapeutic vulnerabilities.

Financial support

The work was in part supported by a Susan G Komen Leadership Grant to SO (SAC160073) and NCI R01 CA252378 (SO/AVL). AVL and SO are Komen Scholars, Hillman Foundation Fellows and supported by BCRF. This project used the UPMC Hillman Cancer Center and Tissue and Research Pathology/Pitt Biospecimen Core shared resource which is supported in part by award P30CA047904. This research was also supported in part by the University of Pittsburgh Center for Research Computing, RRID:SCR_022735, through the resources provided. Specifically, this work used the HTC cluster, which is supported by NIH award number S10OD028483. Finally, partial support was provided by the Magee-Womens Research Institute and Foundation, The Shear Family Foundation, and The Metastatic Breast Cancer Network.

Association of body mass index with clinicopathological features and survival in patients with primary invasive lobular breast cancer

PURPOSE

Invasive lobular carcinoma (ILC) represents up to 15% of all breast carcinomas. While the proportion of women with overweight and obesity increases globally, the impact of body mass index (BMI) at primary diagnosis on clinicopathological features of ILC and the prognosis of the patients has not been investigated yet.

PATIENTS AND METHODS

We performed a multicentric retrospective study including patients diagnosed with non-metastatic pure ILC. The association of BMI at diagnosis with clinicopathological variables was assessed using linear or multinomial logistic regression. Univariable and multivariable survival analyses were performed to evaluate the association of BMI with disease-free survival (DFS), distant recurrence-free survival (DRFS), and overall survival (OS).

RESULTS

The data of 2856 patients with ILC and available BMI at diagnosis were collected, of which 2570/2856 (90.0%) had oestrogen receptor (ER)-positive and human epidermal growth factor receptor (HER2) not amplified/overexpressed (ER+/HER2-) ILC. Of these 2570 patients, 80 were underweight (3.1%), 1410 were lean (54.9%), 712 were overweight (27.7%), and 368 were obese (14.3%). Older age at diagnosis, a higher tumour grade, a larger tumour size, a nodal involvement, and multifocality were associated with a higher BMI. In univariable models, higher BMI was associated with worse outcomes for all end-points (DFS: hazard ratio (HR) 1.21, 95CI 1.12-1.31, p value<0.01; DRFS: HR 1.25, 95CI 1.12-1.40, p value<0.01; OS: HR 1.25, 95CI 1.13-1.37, p value<0.01). This association was not statistically significant in multivariable analyses (DFS: HR 1.09, 95CI 0.99-1.20, p value 0.08; DRFS: HR 1.03, 95CI 0.89-1.20, p value 0.67; OS: HR 1.11, 95CI 0.99-1.24, p value 0.08), whereas grade, tumour size, and nodal involvement were still prognostic for all end-points.

CONCLUSION

Worse prognostic factors such as higher grade, larger tumour size, and nodal involvement are associated with higher BMI in ER+/HER2- ILC, while there was no statistical evidence for an independent prognostic role for BMI. Therefore, we hypothesise that the effect of BMI on survival could be mediated through its association with these clinicopathological variables.

Clinicopathologic and genomic features of lobular like invasive mammary carcinoma: is it a distinct entity?

This study describes "lobular-like invasive mammary carcinomas" (LLIMCas), a group of low- to intermediate-grade invasive mammary carcinomas with discohesive, diffusely infiltrative cells showing retained circumferential membranous immunoreactivity for both E-cadherin and p120. We analyzed the clinical-pathologic features of 166 LLIMCas compared to 104 classical invasive lobular carcinomas (ILCs) and 100 grade 1 and 2 invasive ductal carcinomas (IDCs). Tumor size and pT stage of LLIMCas were intermediate between IDCs and ILCs, and yet often underestimated on imaging and showed frequent positive margins on the first resection. Despite histomorphologic similarities to classical ILC, the discohesion in LLIMCa was independent of E-cadherin/p120 immunophenotypic alteration. An exploratory, hypothesis-generating analysis of the genomic features of 14 randomly selected LLIMCas and classical ILCs (7 from each category) was performed utilizing an FDA-authorized targeted capture sequencing assay (MSK-IMPACT). None of the seven LLIMCas harbored CDH1 loss-of-function mutations, and none of the CDH1 alterations detected in two of the LLIMCas was pathogenic. In contrast, all seven ILCs harbored CDH1 loss-of-function mutations coupled with the loss of heterozygosity of the CDH1 wild-type allele. Four of the six evaluable LLIMCas were positive for CDH1 promoter methylation, which may partially explain the single-cell infiltrative morphology seen in LLIMCa. Further studies are warranted to better define the molecular basis of the discohesive cellular morphology in LLIMCa. Until more data becomes available, identifying LLIMCas and distinguishing them from typical IDCs and ILCs would be justified. In patients with LLIMCas, preoperative MRI should be entertained to guide surgical management.

Clinical outcomes and prognostic factors in triple-negative invasive lobular carcinoma of the breast

PURPOSE

Triple-negative invasive lobular carcinoma (TN-ILC) of breast cancer is a rare disease and the clinical outcomes and prognostic factors are not well-defined.

METHODS

Women with stage I-III TN-ILC or triple-negative invasive ductal carcinoma (TN-IDC) of the breast undergoing mastectomy or breast-conserving surgery between 2010 and 2018 in the National Cancer Database were included. Kaplan-Meier curves and multivariate Cox proportional hazard regression were used to compare overall survival (OS) and evaluate prognostic factors. Multivariate logistic regression was performed to analyze the factors associated with pathological response to neoadjuvant chemotherapy.

RESULTS

The median age at diagnosis for women with TN-ILC was 67 years compared to 58 years in TN-IDC (p < 0.001). There was no significant difference in the OS between TN-ILC and TN-IDC in multivariate analysis (HR 0.96, p = 0.44). Black race and higher TNM stage were associated with worse OS, whereas receipt of chemotherapy or radiation was associated with better OS in TN-ILC. Among women with TN-ILC receiving neoadjuvant chemotherapy, the 5-year OS was 77.3% in women with a complete pathological response (pCR) compared to 39.8% in women without any response. The odds of achieving pCR following neoadjuvant chemotherapy were significantly lower in women with TN-ILC compared to TN-IDC (OR 0.53, p < 0.001).

CONCLUSION

Women with TN-ILC are older at diagnosis but have similar OS compared to TN-IDC after adjusting for tumor and demographic characteristics. Administration of chemotherapy was associated with improved OS in TN-ILC, but women with TN-ILC were less likely to achieve complete response to neoadjuvant therapy compared to TN-IDC.

FDG and Non-FDG Radiopharmaceuticals for PET Imaging in Invasive Lobular Breast Carcinoma

Invasive lobular cancer (ILC) is the second most frequent histological type of breast cancer (BC) and includes a heterogeneous spectrum of diseases with unique characteristics, especially the infiltrative growth pattern and metastatic spread. [¹⁸F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) is extensively used in oncology and BC patient evaluation. Its role in ILCs is considered suboptimal due to its low FDG avidity. Therefore, ILCs could benefit from molecular imaging with non-FDG tracers that target other specific pathways, contributing to precision medicine. This narrative review aims to summarize the current literature on the use of FDG-PET/CT in ILC and to discuss future opportunities given by the development of innovative non-FDG radiotracers.

Evaluation of an Artificial Intelligence System for Detection of Invasive Lobular Carcinoma on Digital Mammography

Introduction Early breast cancer detection with screening mammography has been shown to reduce mortality and improve breast cancer survival. This study aims to evaluate the ability of an artificial intelligence computer-aided detection (AI CAD) system to detect biopsy-proven invasive lobular carcinoma (ILC) on digital mammography. Methods This retrospective study reviewed mammograms of patients who were diagnosed with biopsy-proved ILC between January 1, 2017, and January 1, 2022. All mammograms were analyzed using cmAssist^® (CureMetrix, San Diego, California, United States), which is an AI CAD for mammography. The AI CAD sensitivity for detecting ILC on mammography was calculated and further subdivided by lesion type, mass shape, and mass margins. To account for the within-subject correlation, generalized linear mixed models were implemented to investigate the association between age, family history, and breast density and whether the AI detected a false positive or true positive. Odds ratios, 95% confidence intervals, and p-values were also calculated. Results A total of 124 patients with 153 biopsy-proven ILC lesions were included. The AI CAD detected ILC on mammography with a sensitivity of 80%. The AI CAD had the highest sensitivity for detecting calcifications (100%), masses with irregular shape (82%), and masses with spiculated margins (86%). However, 88% of mammograms had at least one false positive mark with an average number of 3.9 false positive marks per mammogram. Conclusion The AI CAD system evaluated was successful in marking the malignancy in digital mammography. However, the numerous annotations confounded the ability to determine its overall accuracy and this reduces its potential use in real-life practice.

Clinical Outcomes and Prognostic Factors in Triple-Negative Invasive Lobular Carcinoma of the Breast

Purpose: Triple-negative invasive lobular carcinoma (TN-ILC) of breast cancer is a rare disease and the clinical outcomes and prognostic factors are not well-defined. Methods: Women with stage I-III TN-ILC or triple-negative invasive ductal carcinoma (TN-IDC) of the breast undergoing mastectomy or breast-conserving surgery between 2010 and 2018 in the National Cancer Database were included. Kaplan-Meier curves and multivariate Cox proportional hazard regression were used to compare overall survival (OS) and evaluate prognostic factors. Multivariate logistic regression was performed to analyze the factors associated with pathological response to neoadjuvant chemotherapy. Results: The median age at diagnosis for women with TN-ILC was 67 years compared to 58 years in TN-IDC (p<0.001). There was no significant difference in the OS between TN-ILC and TN-IDC in multivariate analysis (HR 0.96, p=0.44). Black race and higher TNM stage were associated with worse OS, whereas receipt of chemotherapy or radiation was associated with better OS in TN-ILC. Among women with TN-ILC receiving neoadjuvant chemotherapy, the 5-year OS was 77.3% in women with a complete pathological response (pCR) compared to 39.8% in women without any response. The odds of achieving pCR following neoadjuvant chemotherapy were significantly lower in women with TN-ILC compared to TN-IDC (OR 0.53, p<0.001). Conclusion: Women with TN-ILC are older at diagnosis but have similar OS compared to TN-IDC after adjusting for tumor and demographic characteristics. Administration of chemotherapy was associated with improved OS in TN-ILC, but women with TN-ILC were less likely to achieve complete response to neoadjuvant therapy compared to TN-IDC.

Invasive Lobular Carcinoma: A Review of Imaging Modalities with Special Focus on Pathology Concordance

Invasive lobular cancer (ILC) is the second most common type of breast cancer. It is characterized by a unique growth pattern making it difficult to detect on conventional breast imaging. ILC can be multicentric, multifocal, and bilateral, with a high likelihood of incomplete excision after breast-conserving surgery. We reviewed the conventional as well as newly emerging imaging modalities for detecting and determining the extent of ILC- and compared the main advantages of MRI vs. contrast-enhanced mammogram (CEM). Our review of the literature finds that MRI and CEM clearly surpass conventional breast imaging in terms of sensitivity, specificity, ipsilateral and contralateral cancer detection, concordance, and estimation of tumor size for ILC. Both MRI and CEM have each been shown to enhance surgical outcomes in patients with newly diagnosed ILC that had one of these imaging modalities added to their preoperative workup.

Non-enhancing malignant lesions of the breast: A case report and review of literature

Due to the elusive nature of invasive lobular carcinoma, mammography, ultrasound, and magnetic resonance imaging have their limitations in early detection. A 67-year-old woman presented for mammography and found retraction of breast parenchyma of the right breast. Magnetic resonance imaging and contrast mammography showed no contrast uptake in the region in question. Magnetic resonance imaging and ultrasound were found to be superior for the detection of invasive lobular carcinoma, with a sensitivity of more than 90%. On ultrasound examination, invasive lobular carcinoma may occur only with posterior acoustic shadowing. On breast magnetic resonance imaging, it is commonly described as an irregular mass and less commonly as non-mass enhancement. An additional advantage of magnetic resonance imaging is the higher detection rate of multifocal, multicentric, and contralateral breast lesions. The reason for no contrast enhancement in this particular tumor before neoadjuvant chemotherapy followed by enhancement after neoadjuvant chemotherapy is most likely at the molecular and histologic level and requires further investigation in similar cases.

Diagnostically Challenging Subtypes of Invasive Lobular Carcinomas: How to Avoid Potential Diagnostic Pitfalls

Invasive lobular carcinoma is the most common special breast carcinoma subtype, with unique morphological (discohesive cells, single-cell files, targetoid pattern) and immunohistochemical (loss of E-cadherin and β-catenin staining) features. Moreover, ILC displays a poor response to neoadjuvant therapy, a different metastatic pattern compared to invasive breast carcinoma of no special type, as well as unique molecular characteristics. In addition to the classic variant of invasive lobular carcinoma, several other well-recognized variants exist, including classic, alveolar, tubulolobular, solid, pleomorphic, signet-ring, and mixed. Furthermore, three novel variants of invasive lobular carcinoma, i.e., with extracellular mucin production, papillary features, and tubular elements, have been described during the last decade. We herewith focus on the unique morphological and immunohistochemical characteristics of these novel varieties of invasive lobular carcinoma, as well as differential diagnostic considerations and potential diagnostic pitfalls, especially when dealing with biopsy specimens.

Multimodality imaging in lobular breast cancer: Differences in mammography, ultrasound, and MRI in the assessment of local tumor extent and correlation with molecular characteristics

Introduction

Invasive lobular breast cancer (ILC) is a diagnostic challenge due to the diversity of morphological features. The objective of the study was to investigate the presentation and local extent of ILC using various imaging techniques and to assess the correlation between imaging and molecular profile.

Materials and methods

We reviewed 162 consecutive patients with ILC found on vacuum-assisted biopsy, who underwent evaluation of the lesion morphology and extent using ultrasound (US), mammography (MMG), and magnetic resonance imaging (MRI). Radiographic features were compared with ILC intrinsic subtype based on the expression of Ki-67 and estrogen, progesterone, and HER2 receptors.

Results

A total of 113 mass lesions and 49 non-mass enhancements (NMEs) were found in MRI. Masses were typically irregular and spiculated, showing heterogeneous contrast enhancement, diffusion restriction, and type III enhancement curve. NMEs presented mainly as the area of focal or multiregional distribution with heterogeneous or clumped contrast enhancement, diffusion restriction, and type III enhancement curve. Lesion extent significantly varied between MRI and MMG/ultrasonography (USG) (P < 0.001) but did not differ between MGF and ultrasonography (USG). The larger the ILC, the higher the disproportion when lesion extent in MRI was compared with MMG (P < 0.001) and ultrasonography (USG) (P < 0.001). In the study group, there were 97 cases of luminal A subtype (59.9%), 54 cases of luminal B HER2− (33.3%), nine cases of luminal B HER2+ (5.5%), and two cases of triple negative (1.2%). The HER2 type was not found in the study group. We did not observe any significant correlation between molecular profile and imaging.

Conclusion

MRI is the most effective technique for the assessment of ILC local extent, which is important for optimal treatment planning. Further studies are needed to investigate if the intrinsic subtype of ILC can be predicted by imaging features on MRI.

Perivascular infiltration reflects subclinical lymph node metastasis in invasive lobular carcinoma

Invasive lobular carcinoma (ILC) is characterized by discohesive cells due to irreversible loss of E-cadherin expression and multiple satellites, where individual cell migration is evident without disturbance of the stroma. Neoplastic cells sometimes infiltrate the surrounding vessel in satellites. Here, we aimed to clarify the specific role of perivascular infiltration (PVI) and ameboid migration, characterized by nondisturbance of the background stromal structure, in ILCs. A total of 139 cases with ILC and 122 cases with invasive breast carcinoma of no special type (IBC-NST) were evaluated retrospectively. PVI was significantly more common in ILC than in IBC-NST (50% [70 of 139 cases] vs. 9% [11 of 122 cases], p < 0.001). ILC cases with PVI showed a larger pathological tumour size than clinical tumour size (p < 0.01), a higher frequency of pathological node status pN2-pN3 when limited to clinically node-negative cases (p < 0.01) and lower circularity of tumour morphology on imaging (p < 0.01) than ILC cases without PVI. In the pathological evaluation, the intensity and occupancy of tumour cells expressing phospho-myosin light chain 2, which is a hallmark of ameboid migration, were significantly higher in ILC cases with PVI than in those without PVI at the tumour margins (p < 0.05). ILC with PVI is associated with irregular, poorly defined tumour margins and lymph node metastasis without adenopathy, which is difficult to assess using imaging. PVI may be caused by ameboid migration, as shown by the positive expression of phospho-myosin light chain 2. The presence of PVI may be a predictor for clinically node-negative pN2-pN3 in ILC patients.

Improving Invasive Breast Cancer Care Using Machine Learning Technology

Breast cancer (BC) is the most common malignancy in women worldwide. In the United States, the lifetime risk of developing an invasive form of breast cancer is 12.5% among women. BC arises in the lining cells (epithelium) of the ducts or lobules in the glandular tissue of the breast. The goal of the present study was to use machine learning (ML) as a novel technology to assess and compare the invasive forms of BC including, infiltrating ductal carcinoma, infiltrating lobular carcinoma, and mucinous carcinoma. To achieve this goal, we used ML algorithms and collected a dataset of 334 BC patients available at https://www.kaggle.com/amandam1/breastcancerdataset and interpreted this dataset based on the form of BC, age, sex, tumor stages, surgery type, and survival rate. Among the 334 patients, 70% were diagnosed with infiltrating ductal carcinoma, 27% with infiltrating lobular carcinoma, and 3% with mucinous carcinoma. Overall, out of 334 BC patients: 64 (19.16%) were in stage I, 189 (56.59%) in stage II, and 81 (24.25%) in stage III. Sixty-six, 67, 96, and 105 patients underwent lumpectomy, simple mastectomy, modified radical mastectomy, and other types of surgery, respectively. The survival rates were 83.4% for stage I, 79.1% for stage II, and 77% for stage III. Findings from the present study demonstrated that ML provides an important tool to curate large amount of BC data, as well as a scientific means to improve BC outcomes.

Current and future diagnostic and treatment strategies for patients with invasive lobular breast cancer

BACKGROUND

Invasive lobular breast cancer (ILC) is the second most common type of breast cancer after invasive breast cancer of no special type (NST), representing up to 15% of all breast cancers.

DESIGN

Latest data on ILC are presented, focusing on diagnosis, molecular make-up according to the European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets (ESCAT) guidelines, treatment in the early and metastatic setting and ILC-focused clinical trials.

RESULTS

At the imaging level, magnetic resonance imaging-based and novel positron emission tomography/computed tomography-based techniques can overcome the limitations of currently used imaging techniques for diagnosing ILC. At the pathology level, E-cadherin immunohistochemistry could help improving inter-pathologist agreement. The majority of patients with ILC do not seem to benefit as much from (neo-)adjuvant chemotherapy as patients with NST, although chemotherapy might be required in a subset of high-risk patients. No differences in treatment efficacy are seen for anti-human epidermal growth factor receptor 2 (HER2) therapies in the adjuvant setting and cyclin-dependent kinases 4 and 6 inhibitors in the metastatic setting. The clinical utility of the commercially available prognostic gene expression-based tests is unclear for patients with ILC. Several ESCAT alterations differ in frequency between ILC and NST. Germline BRCA1 and PALB2 alterations are less frequent in patients with ILC, while germline CDH1 (gene coding for E-cadherin) alterations are more frequent in patients with ILC. Somatic HER2 mutations are more frequent in ILC, especially in metastases (15% ILC versus 5% NST). A high tumour mutational burden, relevant for immune checkpoint inhibition, is more frequent in ILC metastases (16%) than in NST metastases (5%). Tumours with somatic inactivating CDH1 mutations may be vulnerable for treatment with ROS1 inhibitors, a concept currently investigated in early and metastatic ILC.

CONCLUSION

ILC is a unique malignancy based on its pathological and biological features leading to differences in diagnosis as well as in treatment response, resistance and targets as compared to NST.

Management of HR+/HER2+ lobular breast cancer and trends do not mirror better outcomes

PURPOSE

Treatment protocols for invasive lobular breast cancer (ILC) have largely followed those for invasive ductal breast cancer. This study compares treatment outcomes of endocrine therapy versus combined chemo-endocrine therapy in hormone-receptor-positive (HR+), HER2-positive (HER2+) ILC tumors in a large national registry.

METHODS

We sampled the National Cancer Database (2010-2016) for female patients with stages I-III, HR+/HER2+ ILC who underwent surgery. Cochran-Armitage trend test examined trends of treatment regimen administration: Surgery only (S), chemotherapy (C), endocrine therapy (ET), and combined chemo-endocrine therapy (CET), with or without anti-HER2 therapy. Cox proportional hazard model were used to compare overall survival (OS) across ET and CET cohorts, stratifying for anti-HER2 therapy, before and after propensity score match of cohorts (2013-2016). Kaplan-Meier (KM) survival curves were also produced.

RESULTS

N=11,421 were included. 58.7% of patients received Anti-Her2 therapy after 2013. CET conferred better OS over ET in the unmatched (adjusted-5-year-OS: 92.5% vs. 81.1%, p<0.001) and PS-matched (90.4% vs. 84.5%, p=0.001) samples. ET caused lower OS in patients who received Anti-Her2 therapy (HR: 2.56, 95% CI: 1.60-4.12, p<0.001) and patients who did not (HR: 1.84, 95% CI: 1.21-2.78, p=0.004), as compared to CET on multivariable analysis. KM modeling showed highest OS in the CET cohort who received Anti-Her2 (93.0%), followed by the CET cohort who did not receive Anti-Her2 (90.2%) (p=0.06).

CONCLUSION

Chemotherapy followed by endocrine therapy and Anti-Her2 therapy was shown to be the most effective treatment modality in HR+/HER2+ ILC, contrasting previous data on the inconclusive benefit of chemotherapy in patients with ILC.

Mammographically Occult Invasive Lobular Carcinoma With Intradermal Invasion

While shortcomings in the detection of invasive lobular carcinoma (ILC) continue to be studied, research is ongoing to determine detection rates using current breast imaging modalities in combination with physical examination findings. In the following case report, we describe the rare presentation of a patient diagnosed by punch biopsy with grade III, estrogen receptor (ER)-/progesterone receptor (PR)-positive invasive lobular carcinoma with intradermal invasion. This patient presented with findings similar to inflammatory breast cancer (IBC) including pain in the left nipple, skin warmth, and erythema circumferentially encompassing approximately two-thirds of the left breast. This case study is of significance as, to date, it is the first report of an invasive lobular carcinoma that presented clinically as inflammatory breast cancer and was occult on both diagnostic mammography and ultrasound. While imaging remains the primary method of breast cancer detection, it is important to note that clinical findings of dermal invasion of the breast may prompt further investigation with a biopsy and close follow-up, regardless of imaging results.

The prevalence and predictors of adjuvant chemotherapy use among patients treated with neoadjuvant endocrine therapy

PURPOSE

Neoadjuvant endocrine therapy (NET) facilitates clinical response and breast conservation in hormone receptor-positive (HR-positive) breast cancer. Patient selection for adjuvant chemotherapy (CT) post-NET is unclear and potentially evolving with use of genomic assays. We evaluated post-NET CT use in a national dataset.

METHODS

Using the National Cancer DataBase, we identified patients with cT2-3N0-3M0 HR-positive/human epidermal growth factor receptor 2-negative breast cancer treated between 2010 and 2017 with 3-12 months of NET prior to breast surgery. CT use was evaluated in the overall population, in patients with a pathologic complete response (pCR) and in patients with ypT1-2N0 disease (approximating PEPI 0). Exploratory analysis included patients > 50 years with ypN0-1, and 21-gene recurrence score (RS) ≤ 25 (approximating TAILORx/RxPONDER populations not benefiting from CT). Multivariable logistic regression was used to identify factors associated with CT.

RESULTS

Among 3624 eligible patients, 20.4% (740/3624) received CT. On multivariable analysis, age ≤ 50, lobular histology, grade 2, progesterone receptor negativity, ypT3, ypN + and RS ≥ 18 were associated with CT receipt. Co-morbidity, longer NET duration, ypT4, ypNx, and RS < 18 were associated with CT omission. CT was administered to 3.3% (1/30) of patients experiencing pCR and 5.5% (82/1483) with ypT1-2N0 disease. Among patients > 50 years with ypT0-3N0-1 residual disease, 13.8% (355/2569) received CT; RS was available for 24.8% (88/355) and 60% (53/88) had a score 0-25.

CONCLUSION

A minority of patients receive CT post-NET. This decision appears to be driven by younger age, RS and pathological nodal status. Increased consideration of these factors prior to neoadjuvant treatment choice may be warranted.

ROSALINE: a phase II, neoadjuvant study targeting ROS1 in combination with endocrine therapy in invasive lobular carcinoma of the breast

Invasive lobular carcinoma (ILC) is the most common histologic subtype of breast cancer after invasive ductal carcinoma (i.e., no special type [NST]). ILC differs from NST in clinical presentation, site-specific metastases and response to conventional therapies. Loss of E-cadherin protein expression, due to alterations in its encoding gene CDH1, is the most frequent oncogenic event in ILC. Synthetic lethality approaches have shown promising antitumor effects of ROS1 inhibitors in models of E-cadherin-defective breast cancer in in vivo studies and provide the rationale for testing their clinical activity in patients with ILC. Entrectinib is a tyrosine kinase inhibitor targeting TRK, ROS1 and ALK tyrosine kinases. Here, the authors present ROSALINE (NCT04551495), a phase II study testing neoadjuvant entrectinib and endocrine therapy in women with estrogen receptor-positive, HER2-negative early ILC.

Occult Invasive Lobular Carcinoma Presenting as an Axillary Skin Metastatic Lesion Underwent Neoadjuvant Endocrine Therapy and Surgical Resection: A Case Report and Review of Literature

Introduction

Invasive lobular carcinoma (ILC) is the second most common type of breast cancer accounting for 5–15% of all breast cancer cases. It usually presents with nonspecific signs and symptoms. Occult breast cancer presenting as an axillary mass is rare, with prevalence of 0.3–1%, less likely with isolated cutaneous breast metastasis as a first presentation. There are limited data in the literature on patients who underwent endocrine therapy and complete surgical resection.

Case Presentation

A 54-year-old woman with left axillary skin swelling that had been persisting for 6 years was diagnosed with ILC 18 months ago presenting with an ulcerated axillary skin lesion and was managed with letrozole in another facility as she was estrogen receptor (ER) and progesterone receptor (PR) positive. She received letrozole for 18 months and had a partial response in the form of healing of the ulcer with persistent subcutaneous nodules. Her breast mammogram, ultrasound, and magnetic resonance imaging findings were unremarkable; however, there were few prominent left axillary lymph nodes. A biopsy of the left axillary lymph node was positive for malignancy, consistent with ILC. A skin punch biopsy of the axillary skin lesion showed ILC extending to the dermis with no background breast tissue. The patient underwent left modified radical mastectomy with excision of the left axillary skin lesion. The breast specimen comprised 0.4 mm of ILC as the primary malignancy and nine positive axillary lymph node malignancies. The patient received adjuvant radiotherapy and continued to receive letrozole. There were no signs of complications or recurrence during the follow-up period.

Conclusion

Ulcerated skin lesions in the axilla should raise concerns regarding breast cancer metastasis. In cases of isolated cutaneous breast metastases, surgical excision can be considered in combination with endocrine therapy.

Microwave Imaging in Breast Cancer - Results from the First-In-Human Clinical Investigation of the Wavelia System

RATIONALE AND OBJECTIVES

Microwave Breast Imaging (MBI) is an emerging non-ionising technology with the potential to detect breast pathology. The investigational device considered in this article is a low-power electromagnetic wave MBI prototype that demonstrated the ability to detect dielectric contrast between tumour phantoms and synthetic fibroglandular tissue in preclinical studies. Herein, we evaluate the MBI system in the clinical setting. The capacity of the MBI system to detect and localise breast tumours in addition to benign breast pathology is assessed. Secondly, the safety profile and patient experience of this device is established.

MATERIALS AND METHODS

Female patients were recruited from the symptomatic unit to 1 of 3 groups: Biopsy-proven breast cancers (Group-1), unaspirated cysts (Group-2) and biopsy-proven benign breast lesions (Group-3). Breast Density was determined by Volpara VDM (Volumetric Density Measurement) Software. MBI, radiological, pathological and histological findings were reviewed. Subjects were surveyed to assess patient experience.

RESULTS

A total of 25 patients underwent MBI. 24 of these were included in final data analysis (11 Group-1, 8 Group-2 and 5 Group-3). The MBI system detected and localised 12 of 13 benign breast lesions, and 9 out of the 11 breast cancers. This included 1 case of a radiographically occult invasive lobular cancer. No device related adverse events were recorded. 92% (n = 23) of women reported that they would recommend MBI imaging to other women.

CONCLUSION

The MBI system detected and localized the majority of breast lesions. This modality may have the potential to offer a non-invasive, non-ionizing and painless adjunct to breast cancer diagnosis. Further larger studies are required to validate the findings of this study.

The incidence of discordant clinical and genomic risk in patients with invasive lobular or ductal carcinoma of the breast: a National Cancer Database Study

When molecular testing classifies breast tumors as low risk but clinical risk is high, the optimal management strategy is unknown. One group of patients who may be more likely to have such discordant risk are those with invasive lobular carcinoma of the breast. We sought to examine whether patients with invasive lobular carcinoma are more likely to have clinical high/genomic low-risk tumors compared to those with invasive ductal carcinoma, and to evaluate the impact on receipt of chemotherapy and overall survival. We conducted a cohort study using the National Cancer Database from 2010–2016. Patients with hormone receptor positive, HER2 negative, stage I-III breast cancer who underwent 70-gene signature testing were included. We evaluated the proportion of patients with discordant clinical and genomic risk by histology using Kaplan-Meier plots, log-rank tests, and Cox proportional hazards models with and without propensity score matching. A total of 7399 patients (1497 with invasive lobular carcinoma [20.2%]) were identified. Patients with invasive lobular carcinoma were significantly more likely to fall into a discordant risk category compared to those with invasive ductal carcinoma (46.8% versus 37.1%, p < 0.001), especially in the clinical high/genomic low risk subgroup (35.6% versus 19.2%, p < 0.001). In unadjusted analysis of the clinical high/genomic low-risk cohort who received chemotherapy, invasive ductal carcinoma patients had significantly improved overall survival compared to those with invasive lobular carcinoma (p = 0.02). These findings suggest that current tools for stratifying clinical and genomic risk could be improved for those with invasive lobular carcinoma to better tailor treatment selection.

Germline Pathogenic Variants in Cancer Predisposition Genes Among Women With Invasive Lobular Carcinoma of the Breast

PURPOSE

To determine the contribution of germline pathogenic variants (PVs) in hereditary cancer testing panel genes to invasive lobular carcinoma (ILC) of the breast.

MATERIALS AND METHODS

The study included 2,999 women with ILC from a population-based cohort and 3,796 women with ILC undergoing clinical multigene panel testing (clinical cohort). Frequencies of germline PVs in breast cancer predisposition genes (ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, PALB2, PTEN, RAD51C, RAD51D, and TP53) were compared between women with ILC and unaffected female controls and between women with ILC and infiltrating ductal carcinoma (IDC).

RESULTS

The frequency of PVs in breast cancer predisposition genes among women with ILC was 6.5% in the clinical cohort and 5.2% in the population-based cohort. In case-control analysis, CDH1 and BRCA2 PVs were associated with high risks of ILC (odds ratio [OR] > 4) and CHEK2, ATM, and PALB2 PVs were associated with moderate (OR = 2-4) risks. BRCA1 PVs and CHEK2 p.Ile157Thr were not associated with clinically relevant risks (OR < 2) of ILC. Compared with IDC, CDH1 PVs were > 10-fold enriched, whereas PVs in BRCA1 were substantially reduced in ILC.

CONCLUSION

The study establishes that PVs in ATM, BRCA2, CDH1, CHEK2, and PALB2 are associated with an increased risk of ILC, whereas BRCA1 PVs are not. The similar overall PV frequencies for ILC and IDC suggest that cancer histology should not influence the decision to proceed with genetic testing. Similar to IDC, multigene panel testing may be appropriate for women with ILC, but CDH1 should be specifically discussed because of low prevalence and gastric cancer risk.

Palpable multifocal and multicentric invasive lobular breast carcinoma in a young female

Breast cancer is the most common carcinoma plaguing women in the United States. Invasive lobular carcinoma is the second most prevalent type of breast carcinoma with an incidence rate of 5% and 15% with high propensity for multifocal manifestation of disease. Multifocal disease is defined by two or more malignant foci within a single quadrant. Invasive lobular carcinoma is strongly associated with early menarche, late menopause, late age at first birth, and is typically seen in women ages 50 and older. Invasive lobular carcinoma can be difficult to detect clinically because lesions typically fail to form palpable masses, and it can be challenging to diagnose mammographically due to subtle imaging features of the lesions. Here we present a rare case of a palpable, unilateral, multifocal and multicentric lobular breast carcinoma in a young, previously healthy 41-year-old woman with no family history of breast cancer.

St Gallen 2019 guidelines understage the axilla in lobular breast cancer: a population-based study

BACKGROUND

The St Gallen 2019 guidelines for primary therapy of early breast cancer recommend omission of completion axillary lymph node dissection (cALND), regardless of histological type, in patients with one or two sentinel lymph node (SLN) metastases. Concurrently, adjuvant chemotherapy is endorsed for luminal A-like disease with four or more axillary lymph node (ALN) metastases. The aim of this study was to estimate the proportion of patients with invasive lobular cancer (ILC) versus invasive ductal cancer of no special type (NST) with one or two SLN metastases for whom cALND would have led to a recommendation for adjuvant chemotherapy.

METHODS

Patients with ILC and NST who had surgery between 2014 and 2017 were identified in the National Breast Cancer Register of Sweden. After exclusion of patients with incongruent or missing data, those who fulfilled the St Gallen 2019 criteria for cALND omission were included in the population-based study cohort.

RESULTS

Some 1886 patients in total were included in the study, 329 with ILC and 1507 with NST. Patients with ILC had a higher metastatic nodal burden and were more likely to have a luminal A-like subtype than those with NST. The prevalence of at least four ALN metastases was higher in ILC (31.0 per cent) than NST (14.9 per cent), corresponding to an adjusted odds ratio of 2.26 (95 per cent c.i. 1.59 to 3.21). Luminal A-like breast cancers with four or more ALN metastases were over-represented in ILC compared with NST, 52 of 281 (18.5 per cent) versus 43 of 1299 (3.3 per cent) (P < 0.001).

CONCLUSION

Patients with ILC more often have luminal A-like breast cancer with at least four nodal metastases. Omission of cALND in patients with luminal A-like invasive lobular cancer and one or two SLN metastases warrants future attention as there is a risk of nodal understaging and undertreatment in one-fifth of patients.

Prolonged Time from Diagnosis to Breast-Conserving Surgery is Associated with Upstaging in Hormone Receptor-Positive Invasive Ductal Breast Carcinoma

BACKGROUND

Time to surgery (TTS) has been suggested to have an association with mortality in early-stage breast cancer.

OBJECTIVE

This study aims to determine the association between TTS and preoperative disease progression in tumor size or nodal status among women diagnosed with clinical T1N0M0 ductal breast cancer.

METHODS

Women diagnosed with clinical T1N0M0 ductal breast cancer who had breast-conserving surgery as their first definitive treatment between 2010 and 2016 (n = 90,405) were analyzed using the National Cancer Database. Separate multivariable logistic regression models for hormone receptor (HR)-positive and HR-negative patients, adjusted for clinical and demographic variables, were used to assess the relationship between TTS and upstaging of tumor size (T-upstaging) or nodal status (N-upstaging).

RESULTS

T-upstaging occurred in 6.76% of HR-positive patients and 11.00% of HR-negative patients, while N-upstaging occurred in 12.69% and 10.75% of HR-positive and HR-negative patients, respectively. Among HR-positive patients, odds of T-upstaging were higher for 61-90 days TTS (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.05-1.34) and ≥91 days TTS (OR 1.47, 95% CI 1.17-1.84) compared with ≤30 days TTS, and odds of N- upstaging were higher for ≥91 days TTS (OR 1.35, 95% CI 1.13-1.62). No association between TTS and either T- or N-upstaging was found among HR-negative patients. Other clinical and demographic variables, including grade, tumor location, and race/ethnicity, were associated with both T- and N-upstaging.

CONCLUSION

TTS ≥61 and ≥91 days was a significant predictor of T- and N-upstaging, respectively, in HR-positive patients; however, TTS was not associated with upstaging in HR-negative breast cancer. Delays in surgery may contribute to measurable disease progression in T1N0M0 ductal breast cancer.