Types of carcinoma breast

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Types of Carcinoma Breast: An Overview

Breast cancer is a heterogeneous disease with various histological subtypes, each with distinct clinical, pathological, and molecular characteristics. Understanding these subtypes is crucial for accurate diagnosis, prognosis, and treatment. This article provides an overview of the different types of breast carcinoma, focusing on their unique features and clinical implications.

Invasive Ductal Carcinoma (IDC)

Prevalence and Characteristics

Invasive ductal carcinoma not otherwise specified (IDC NOS) is the most common type of breast cancer, accounting for approximately 75% of all cases. IDC NOS is characterized by its lack of specific histological features that would classify it into other subtypes.

Molecular Subtypes

IDC NOS can be further classified into molecular subtypes such as luminal A, luminal B, HER2-positive, and basal-like, based on gene expression profiles. These subtypes have different prognostic and therapeutic implications.

Invasive Lobular Carcinoma (ILC)

Prevalence and Characteristics

Invasive lobular carcinoma (ILC) is the second most common type, accounting for up to 15% of breast cancer cases. ILC is noted for its lack of E-cadherin function, leading to a discohesive growth pattern with cells arranged in single file.

Molecular Features

ILC tumors are typically luminal in molecular subtype, being estrogen and progesterone receptor-positive and HER2-negative. Recent research has focused on the genomic landscape of ILC, revealing potential therapeutic targets.

Special Histological Types

Salivary Gland-Type Carcinomas

These rare types of breast carcinoma resemble those found in salivary glands and include adenoid cystic carcinoma and secretory carcinoma. They often share molecular genetic alterations with their salivary gland counterparts but have diverse prognostic outcomes.

Mucinous, Tubular, and Papillary Carcinomas

Mucinous, tubular, and papillary carcinomas are generally associated with a favorable prognosis. These types are less likely to present at an advanced stage and often have lower rates of node metastasis .

Medullary and Metaplastic Carcinomas

Medullary carcinoma, characterized by a high grade and lymphoid stroma, and metaplastic carcinoma, known for its diverse histologies, are associated with more aggressive clinical behavior. Medullary carcinoma often presents as triple-negative, while metaplastic carcinoma shows varied molecular profiles .

Micropapillary Carcinoma

Invasive micropapillary carcinoma (IMPC) is noted for its high potential for lymphovascular invasion and higher histological grade. IMPC often requires extended surgical margins and vigilant preoperative axillary staging due to its aggressive nature.

Molecular and Histological Correlations

Genotypic-Phenotypic Correlations

Recent studies have identified specific genetic alterations associated with certain histological types. For example, secretory carcinomas consistently harbor the ETV6-NTRK3 fusion gene, while adenoid cystic carcinomas display the MYB-NFIB translocation. These genetic markers are crucial for accurate diagnosis and targeted therapy.

Prognostic Implications

Histological special types of breast cancer, such as medullary and adenoid cystic carcinomas, often display molecular profiles associated with poor prognosis, such as the basal-like transcriptome. However, their clinical outcomes can vary, highlighting the importance of precise histological classification for prognostication and treatment planning.

Conclusion

Breast carcinoma encompasses a diverse group of histological and molecular subtypes, each with unique clinical and prognostic features. Accurate classification and understanding of these subtypes are essential for effective diagnosis, treatment, and management of breast cancer. Advances in molecular genetics continue to refine our understanding, offering new avenues for targeted therapies and improved patient outcomes.