Lobular breast cancer is a rare but distinct type of breast cancer that begins in the breast’s milk-producing glands, or lobules. Although lobular breast cancer only makes up 10–15% of all cases of breast cancer, it has distinct pathological and clinical characteristics that affect diagnosis, management, and treatment.
In this article, we will look at the various subtypes of lobular breast cancer, how they differ from ductal cancers, and what diagnostic and treatment strategies are used to manage them successfully.
What is Lobular Breast Cancer?
Lobular breast cancer develops in the lobules and typically spreads in a single-file pattern through breast tissue. Unlike ductal carcinoma, lobular carcinoma may not form a distinct lump, making it more difficult to detect using standard imaging, such as mammograms.
This subtle growth pattern frequently leads to a delayed diagnosis, emphasizing the importance of understanding the symptoms, subtypes, and clinical behavior.
Types of Lobular Breast Cancer
There are several subtypes of lobular breast cancer, each with its own characteristics and treatment implications.
1. Invasive Lobular Carcinoma (ILC)
ILC is the most common subtype, accounting for 5% to 15% of all breast cancer cases. Small cancer cells invade surrounding tissue in a linear or single-file pattern. Because ILC rarely produces a defined tumor mass, mammograms may miss it and require advanced imaging, such as MRI or ultrasound.
- No well-defined lump
- Often hormone receptor-positive
- Slow-growing but can be bilateral or multifocal
2. Pleomorphic Lobular Carcinoma (PLC)
This is a rare and aggressive subtype of cancer that is distinguished by pleomorphic (abnormally shaped) cells with enlarged nuclei. It is classified as a high-grade tumor, with faster progression and a higher risk of recurrence.
Key Features:
- Higher-grade, fast-growing
- May require aggressive treatment (chemo + targeted therapy)
- Poorer prognosis compared to classic ILC
3. Mixed Lobular and Ductal Carcinoma
This hybrid tumor exhibits both ductal and lobular features. It could represent two different cancers in one breast or have a common cause.
Key Features:
- Variable response to treatment
- needs a thorough histopathological examination.
- A multidisciplinary approach is often used in management.
Diagnosing Lobular Breast Cancer
Because lobular breast cancer does not form masses, diagnosing it is more complicated than other types. This is how physicians usually assess it:
Imaging Tests
- Mammography: Often shows subtle architectural distortion or asymmetry.
- Ultrasound: Capable of identifying anomalies not visible on mammograms.
- Breast MRI: The best method for identifying ILC, particularly in women who have dense breasts or may have multifocal disease.
Biopsy & Pathology
To confirm the diagnosis, a surgical excision or core needle biopsy is needed. ILC is identified by small, round cancer cells infiltrating the breast tissue linearly.
Molecular Profiling
Assessing the tumor’s HER2 status, hormone receptor (HR) status, and other indicators aids in treatment customization. The majority of lobular cancers are HER2 negative and estrogen receptor (ER) positive.
Treatment Options for Lobular Breast Cancer
Treatment is based on the tumor subtype, stage, grade, hormone status, and patient preferences. Options include:
1. Surgery
- Lumpectomy (breast-conserving surgery): Removes only the tumor with margins.
- Mastectomy: Required if the tumor is large or multifocal.
- Sentinel lymph node biopsy: Determines if cancer has spread to lymph nodes.
2. Radiation Therapy
Typically given after lumpectomy to reduce the risk of local recurrence. May also be used post-mastectomy if certain high-risk features are present.
3. Hormonal Therapy
Since most lobular tumors are hormone receptor-positive, patients often benefit from
- Tamoxifen
- Aromatase inhibitors
- Ovarian suppression therapy (in premenopausal women)
These drugs work by blocking estrogen, which fuels tumor growth.
4. Chemotherapy
Indicated for:
- High-grade tumors
- Hormone receptor-negative cancers
- Patients with aggressive subtypes like PLC
May be used before (neoadjuvant) or after surgery (adjuvant).
5. Targeted Therapy
Patients with HER2-positive lobular cancer may receive:
- Trastuzumab (Herceptin)
- Pertuzumab (Perjeta)
These drugs specifically target cancer cells overexpressing the HER2 protein.
Final Thoughts
Lobular breast cancer is a distinct and frequently underdiagnosed type of breast cancer. Its subtle imaging characteristics and infiltrative growth pattern necessitate specialized diagnostic approaches. Fortunately, advances in molecular profiling, imaging, and targeted therapies have improved prognosis as well as treatment personalization.
The best results for patients with this complicated form of breast cancer can be ensured by clinicians who are aware of its various types, including ILC, PLC, and mixed types, and who adjust care plans accordingly.
FAQs
Why is lobular breast cancer harder to detect than other types?
Lobular breast cancer is less noticeable on routine imaging tests like mammograms because it spreads in a single-file pattern and frequently does not form a noticeable lump. It typically requires advanced imaging such as MRI or ultrasound for accurate detection.
What are the main subtypes of lobular breast cancer?
Pleomorphic Lobular Carcinoma (PLC), Invasive Lobular Carcinoma (ILC), and Mixed Lobular and Ductal Carcinoma are the main subtypes. Each has unique characteristics, progression rates, and treatment responses.
How is pleomorphic lobular carcinoma different from classic ILC?
Compared to classic ILC, pleomorphic lobular carcinoma (PLC) is more aggressive, has irregularly shaped cancer cells, and progresses more quickly. It often requires more intensive treatment, including chemotherapy and targeted therapy.
What imaging techniques are most effective for diagnosing lobular breast cancer?
Particularly in women with dense breast tissue, MRI is thought to be the most sensitive imaging modality for detecting lobular breast cancer. Additionally, abnormalities that mammography may overlook may be detected by ultrasound.
Why is molecular profiling important in treating lobular breast cancer?
By identifying the hormone receptor and HER2 status of the tumor, molecular profiling enables physicians to better tailor treatments such as hormonal therapy or targeted medications.
