Clinicopathological characteristics and survival outcomes of invasive lobular carcinoma in different races

Area Deprivation Index in Patients with Invasive Lobular Carcinoma of the Breast: Associations with Tumor Characteristics and Outcomes

BACKGROUND

Although investigators have shown associations between socioeconomic status (SES) and outcomes in breast cancer, there is a paucity of such data for invasive lobular carcinoma (ILC), the second most common type of breast cancer. Herein we evaluated the relationship between SES with tumor features and outcomes in stage I to III patients with ILC.

METHODS

We analyzed a prospectively maintained institutional ILC database and utilized the area deprivation index (ADI) to determine neighborhood adversity, an indicator of SES. We used Cox proportional hazards models in Stata 17.0 to evaluate relationships between ADI quintile (Q), race, body mass index (BMI), clinicopathologic features, treatment type, and event-free survival (EFS).

RESULTS

Of 804 patients with ILC, 21.4% lived in neighborhoods classified as ADI Q1 (least resource-deprived) and 19.7% in Q5 (most resource-deprived). Higher deprivation was significantly associated with larger tumor size (3.6 cm in Q5 vs. 3.1 cm in Q1), increased presence of lymphovascular invasion (8.9% in Q5 vs. 6.7% in Q1), and decreased use of adjuvant endocrine therapy (67.1% in Q5 vs. 73.6% in Q1). On multivariable analysis, tumor size, receptor subtypes, and omission of adjuvant endocrine therapy were associated with reduced EFS.

CONCLUSIONS

These data show that patients with ILC and higher ADI experience more aggressive tumors and differences in treatment. More data evaluating the complex relationships between these factors is needed to optimize outcomes for patients with ILC, regardless of SES.

IMPACT

ADI is associated with differences in patients with ILC.

Differences in Tumour Aggressiveness Based on Molecular Subtype and Race Measured by [18F]FDG PET Metabolic Metrics in Patients with Invasive Carcinoma of the Breast

Breast cancer in women of African descent tends to be more aggressive with poorer prognosis. This is irrespective of the molecular subtype. [¹⁸F]FDG PET/CT metrics correlate with breast cancer aggressiveness based on molecular subtype. This study investigated the differences in [¹⁸F]FDG PET/CT metrics of locally advanced invasive ductal carcinoma (IDC) among different racial groups and molecular subtypes. Qualitative and semiquantitative readings of [¹⁸F]FDG PET/CT acquired in women with locally advanced IDC were performed. Biodata including self-identified racial grouping and histopathological data of the primary breast cancer were retrieved. Statistical analysis for differences in SUVmax, MTV and TLG of the primary tumour and the presence of regional and distant metastases was conducted based on molecular subtype and race. The primary tumour SUVmax, MTV, TLG and the prevalence of distant metastases were significantly higher in Black patients compared with other races (p < 0.05). The primary tumour SUVmax and presence of distant metastases in the luminal subtype and the primary tumour SUVmax and TLG in the basal subtype were significantly higher in Black patients compared with other races (p < 0.05). The significantly higher PET parameters in Black patients with IDC in general and in those with luminal and basal carcinoma subtypes suggest a more aggressive disease phenotype in this race.

Mixed invasive ductal lobular carcinoma is clinically and pathologically more similar to invasive lobular than ductal carcinoma

BACKGROUND

Mixed invasive ductal lobular carcinoma (mDLC) remains a poorly understood subtype of breast cancer composed of coexisting ductal and lobular components.

METHODS

We sought to describe clinicopathologic characteristics and determine whether mDLC is clinically more similar to invasive ductal carcinoma (IDC) or invasive lobular carcinoma (ILC), using data from patients seen at the University of Pittsburgh Medical Center.

RESULTS

We observed a higher concordance in clinicopathologic characteristics between mDLC and ILC, compared to IDC. There is a trend for higher rates of successful breast-conserving surgery after neoadjuvant chemotherapy in patients with mDLC compared to patients with ILC, in which it is known to be lower than in those with IDC. Metastatic patterns of mDLC demonstrate a propensity to develop in sites characteristic of both IDC and ILC. A meta-analysis evaluating mDLC showed shared features with both ILC and IDC with significantly more ER-positive and fewer high grades in mDLC compared to IDC, although mDLCs were significantly smaller and included fewer late-stage tumours compared to ILC.

CONCLUSIONS

These findings support clinicopathologic characteristics of mDLC driven by individual ductal vs lobular components and given the dominance of lobular pathology, mDLC features are often more similar to ILC than IDC. This study exemplifies the complexity of mixed disease.

Clinicopathological Features and Outcomes Comparing Patients With Invasive Ductal and Lobular Breast Cancer

BACKGROUND

There is increasing interest in better understanding the biology and clinical presentation of invasive lobular cancer (ILC), which is the most common special histological subtype of breast cancer. Limited large contemporary data sets are available allowing comparison of clinicopathologic features between ILC and invasive ductal cancer (IDC).

METHODS

The Great Lakes Breast Cancer Consortium was formed to compare clinical behavior of ILC (n = 3617) and IDC (n = 30 045) from 33 662 patients treated between 1990 and 2017 at 3 large clinical centers. We used Kaplan-Meier analysis, Cox proportional hazards modeling, and propensity score matching to evaluate treatment differences and outcomes. All statistical testing used 2-sided P values.

RESULTS

Compared with IDC, patients with ILC were more frequently diagnosed at later stages and with more lymph node involvement (corrected P < .001). Estrogen receptor-positive ILCs were of lower grade (grade 1 and 2: 90% in ILC vs 72% in IDC) but larger in size (T3 and 4: 14.3% in ILC vs 3.4% in IDC) (corrected P < .001), and since 1990, the mean ILC size detected at diagnosis increased yearly. Patients with estrogen receptor (ER)-positive ILC underwent statistically significantly more mastectomies compared with ER-positive IDC (57% vs 46%). Using Kaplan-Meier analysis, patients with ER-positive ILC had statistically significantly worse disease-free survival and overall survival than ER-positive IDC although 6 times more IDCs were classified as high risk by OncotypeDx Breast Recurrence Score assay.

CONCLUSIONS

This large, retrospective, collaborative analysis with 3 clinical centers identified meaningful differences in clinicopathological features between ILC and IDC, providing further evidence that these are 2 different entities requiring different clinical management.

Invasive lobular carcinoma: clinicopathological features and subtypes

Objective

To analyze the characteristics of invasive lobular carcinoma (ILC) compared with invasive ductal carcinoma (IDC) and to investigate the impact of histology on axillary lymph node (ALN) involvement in luminal A subtype tumors.

Methods

We retrospectively analyzed patients diagnosed with ILC or IDC from 2012 to 2016 who underwent surgery. Patients constituted 493 primary early breast cancer cases (82 ILC; 411 IDC).

Results

Compared with IDC, ILC tumors were significantly more likely to be grade 2, estrogen receptor- (ER) positive (+), have a lower proliferation rate (Ki67 <14%), and a higher pathological T stage (pT2–4). The luminal A subtype was significantly more common in ILC compared with IDC. In a multivariate regression model, grade 2, ER+, progesterone receptor-positive, pT2, and pT3 were significantly associated with ILC. Additionally, with the luminal A subtype, ALN involvement (pathological node stage (pN)1–3) was significantly more frequent with ILC versus IDC.

Conclusions

Our data suggest that grade 2, positive hormone receptor status, and higher pathological T stage are associated with ILC. With the luminal A subtype, ALN involvement was more frequent with ILC versus IDC.

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.