Types of Lobular Breast Cancer

Breast cancer is a heterogeneous disease with diverse subtypes, each with its own distinct characteristics and treatment implications. Lobular breast cancer, while less common than ductal breast cancer, presents unique challenges due to its distinct histological features and clinical behavior. In this article, we will delve into the various types of lobular breast cancer, shedding light on their differences, diagnostic considerations, and treatment approaches.

What is Lobular Breast cancer?

Lobular breast cancer arises from the lobules, the milk-producing glands of the breast. Unlike ductal breast cancer, which originates from the milk ducts, lobular breast cancer accounts for approximately 10–15% of all breast cancer cases. Lobular breast cancer is characterized by a unique growth pattern, with cancer cells infiltrating the surrounding breast tissue in a single-file pattern, making it less likely to form a distinct mass on imaging studies such as mammograms.

Types of Lobular Breast Cancer

Lobular breast cancer encompasses several histological subtypes, each with its own distinct features and implications for diagnosis and treatment. The main types of lobular breast cancer include the following:

1. Invasive Lobular Carcinoma (ILC):

Invasive lobular carcinoma (ILC) is the most common type of lobular breast cancer, accounting for approximately 5–15% of all breast cancer cases. In ILC, cancer cells invade the surrounding breast tissue in a linear or single-file pattern, often without forming a well-defined tumor mass. This infiltrative growth pattern can make ILC challenging to detect on imaging studies and may require additional diagnostic modalities such as magnetic resonance imaging (MRI) or breast ultrasound for accurate diagnosis.

2. Pleomorphic Lobular Carcinoma (PLC):

Pleomorphic lobular carcinoma (PLC) is a rare and aggressive subtype of lobular breast cancer characterized by the presence of pleomorphic or irregularly shaped cancer cells with enlarged nuclei and prominent nucleoli. PLC often presents with higher-grade features and more aggressive clinical behavior compared to classic ILC. Due to its rarity and aggressive nature, PLC may require more aggressive treatment approaches, including chemotherapy and targeted therapy.

3. Mixed Lobular and Ductal Carcinoma:

Mixed lobular and ductal carcinoma refers to breast cancer tumors that contain both lobular and ductal features. These tumors may arise from a common precursor cell or represent a collision tumor, where two distinct types of breast cancer develop independently within the same breast. Mixed lobular and ductal carcinomas may present unique challenges in diagnosis and treatment planning, requiring a multidisciplinary approach to management.

Diagnostic Strategies

Diagnosing lobular breast cancer can be challenging due to its subtle imaging characteristics and infiltrative growth pattern. Key diagnostic considerations for lobular breast cancer include:

1. Imaging Studies: Mammography is often the initial imaging modality used for breast cancer screening and detection. However, ILC may present as subtle asymmetries or architectural distortions on mammograms, making it less conspicuous compared to ductal breast cancer. Breast ultrasound and MRI may be more sensitive for detecting ILC, particularly in women with dense breast tissue.

2. Pathological Evaluation: Definitive diagnosis of lobular breast cancer requires histological examination of tissue samples obtained through biopsy or surgical excision. Invasive lobular carcinoma is characterized by the presence of single-file or linear infiltrating cancer cells within the breast tissue, often lacking the cohesive architecture seen in ductal carcinoma.

3. Molecular Profiling: Molecular profiling of lobular breast cancer tumors can provide valuable information about their biological characteristics, including hormone receptor status, HER2 status, and expression of other molecular markers. This information helps guide treatment decisions and identify potential therapeutic targets for personalized therapy approaches.

Lines Of Treatment

Treatment approaches for lobular breast cancer depend on various factors, including tumor size, grade, hormone receptor status, HER2 status, and the patient’s overall health and preferences. Treatment options may include:

1. Surgery: Surgical options for lobular breast cancer may include lumpectomy (partial mastectomy) or mastectomy (complete removal of the breast). A sentinel lymph node biopsy or axillary lymph node dissection may be performed to assess lymph node involvement.

2. Radiation Therapy: Radiation therapy may be recommended following breast-conserving surgery (lumpectomy) to reduce the risk of local recurrence. In some cases, radiation therapy may also be recommended after mastectomy, depending on the presence of certain high-risk features.

3. Hormonal Therapy: Hormonal therapy, also known as endocrine therapy, is often recommended for hormone receptor-positive lobular breast cancer. This may include drugs such as tamoxifen, aromatase inhibitors, or ovarian suppression to block the effects of estrogen on cancer cells.

4. Chemotherapy: Chemotherapy may be recommended for certain subtypes of lobular breast cancer, particularly those with higher-grade features or aggressive clinical behavior. Chemotherapy may be used as neoadjuvant therapy (before surgery) or adjuvant therapy (after surgery) to reduce the risk of recurrence and improve outcomes.

5. Targeted Therapy: Targeted therapy drugs such as trastuzumab (Herceptin) or pertuzumab (Perjeta) may be recommended for HER2-positive lobular breast cancer. These drugs specifically target cancer cells that overexpress the HER2 protein, leading to improved treatment outcomes.

Final Note

Lobular breast cancer represents a heterogeneous group of tumors with distinct histological subtypes and clinical characteristics. Despite its challenges in diagnosis and treatment, advances in imaging technology, molecular profiling, and targeted therapies have improved our understanding of lobular breast cancer and expanded treatment options for patients. By embracing a multidisciplinary approach to management and tailoring treatment strategies to individual patient needs, healthcare providers can optimize outcomes and improve quality of life for individuals affected by lobular breast cancer.