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

Abstract

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 ERpositive 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. The Oncologist 2021;25:1-11 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.

Circulating Glypican-4 Is a Predictor of 24-Month Overall Survival in Metastatic Breast Cancer

“…With regard to the latter, plasma GPC4 levels were highly and significantly increased in patients with ILC compared to NST breast cancer patients. Although ILC remains an understudied entity, long-term survival and clinical outcomes in patients with ILC seem to be worse than in stage-and grade-matched patients with IDC [26]. In our study, both ILC and GPC4 were associated with a worse prognosis, but our study's multivariable Cox regression analysis revealed that the significant association between GPC4 and OS was independent of the histologic type of tumor.…”

Quantification of Extracellular Volume in CT in Neoadjuvant Chemotherapy in Breast Cancer: New Frontiers in Assessing the Cardiotoxicity of Anthracyclines and Trastuzumab

“…The main adjuvant and neoadjuvant chemotherapy regimens involve [ 5 ] the use of anthracyclines (AC), although recently new AC-free schemes are recommended for Her-2 positive BC [ 6 , 7 ] and in postmenopausal women presenting with a luminal-like lobular histotype where an endocrine therapy is preferred [ 8 , 9 ]. Indeed, AC and trastuzumab are among the most efficient antineoplastic drugs, particularly in triple negative BC (TNBC) and HER-2 positive BC, respectively, but they are burdened with an important cardiotoxicity (CTX) rate [ 10 , 11 ], especially doxorubicin (DOX) [ 12 ].…”

Diagnostic Challenge of Invasive Lobular Carcinoma of the Breast: What Is the News? Breast Magnetic Resonance Imaging and Emerging Role of Contrast-Enhanced Spectral Mammography

“…Invasive lobular carcinoma is an independent entity among breast cancers with specific epidemiological, biological and clinical characteristics [ 1 , 2 , 3 , 4 ].…”

“…Invasive lobular carcinoma (ILC) is the second most common type of invasive breast cancer accounting for 5–15% of cases [ 1 , 2 , 3 ]. The incidence of ILC is highest in white older women [ 4 ] and over the last two decades it has increased, also due to the use of hormone replacement therapies [ 5 , 6 , 7 , 8 , 9 ].…”