Invasive Lobular Carcinoma (ILC) is a type of breast cancer that starts in the lobules—tiny glands in the breast that produce milk. These lobules are part of the terminal duct lobular units, which also help carry milk to the nipple. When cancer cells grow in these lobules and begin to spread into nearby breast tissue, it’s known as invasive lobular carcinoma.
Invasive Lobular Carcinoma (ILC) is the second most common type of breast cancer, accounting for 10–15% of all invasive cases and affecting around 31,000 to 46,000 women annually in the U.S. Known for its slow and subtle growth, ILC often lacks a distinct lump, making it harder to detect through physical exams or mammograms. Most cases are hormone receptor-positive, meaning they grow in response to estrogen, which helps guide treatment. While early diagnosis improves outcomes, ILC can still spread or recur years after treatment, emphasizing the need for ongoing monitoring.
Symptoms of Invasive Lobular Carcinoma (ILC)
Early Stages May Show No Signs
In the beginning, invasive lobular breast cancer often doesn’t cause noticeable symptoms. Because it tends to grow slowly and doesn’t usually form a hard lump, it can be difficult to detect during a self-exam or routine screening.
Common Symptoms as ILC Progresses
As the cancer grows, you may begin to notice some changes in your breast, including:
- A thickened area in a part of the breast
- A swelling in one area of the breast
- Dimpling or thickening of the skin over the breast
- An inverted nipple (turned inward)
- Subtle changes in breast shape or size
Unlike other breast cancers, ILC is less likely to cause a firm or easily felt lump, which makes it harder to spot without imaging.
When to See a Doctor
It’s important to talk to a healthcare provider if you notice:
- Any unusual changes in your breast
- A new lump, even if it feels soft or hard to define
- An area of puckered or thickened skin
- Nipple discharge not related to breastfeeding
Don’t Skip Routine Screening
Speak with your healthcare provider about when to start regular breast cancer screening. In most cases, screening is recommended starting in your 40s, but it may vary based on personal risk factors and family history.
Causes of Invasive Lobular Carcinoma (ILC)
The exact cause of invasive lobular breast cancer is still not fully understood. Like many other cancers, it begins when cells in the breast lobules develop changes (mutations) in their DNA. These mutations tell the cells to grow and divide uncontrollably, eventually forming cancer. Over time, these abnormal cells can invade surrounding tissue and even spread to other parts of the body.
Hormonal Influence
ILC is often sensitive to hormones, especially estrogen. This means the cancer may grow in response to estrogen in the body. That’s why hormone-related factors—like early menstruation, late menopause, or hormone replacement therapy (HRT)—may increase the risk of developing ILC.
Genetic Mutations
In some cases, inherited gene mutations like BRCA1, BRCA2, or CDH1 may play a role in causing lobular breast cancer. These mutations can be passed down through families, increasing the risk of ILC and other types of breast cancer.
Cell Adhesion Changes
ILC often involves the loss of a protein called E-cadherin, which helps cells stick together. When this protein is missing or not working properly, it becomes easier for cancer cells to spread into surrounding tissue, which is a key feature of how ILC breast cancer behaves differently from other types.
Still Under Research
Researchers continue to study what triggers these mutations and how lifestyle, environment, and hormones contribute. While we know some risk factors, the actual cause in most cases remains unknown.
Diagnosis of Invasive Lobular Carcinoma (ILC)
Invasive lobular carcinoma is a slow-growing breast cancer but detecting it early can be difficult. Unlike some other breast cancers, ILC often doesn’t form a clear lump and may not show up well on a standard mammogram. As a result, tumors may become quite large by the time they are found.
Diagnostic Tests for ILC
To confirm a diagnosis, especially if a mammogram or physical exam reveals something unusual, your doctor may recommend further testing:
1. Breast MRI (Magnetic Resonance Imaging)
A breast MRI creates detailed images of the inside of your breast using magnetic fields. It helps detect the exact size of the tumor, whether there are multiple tumors, and if the cancer has spread within the breast tissue. This test is especially useful in identifying ILC breast cancer, which can be hard to spot using other methods.
2. Breast Ultrasound
This test uses sound waves to create images of your breast tissue. It’s completely painless and involves moving a small device (called a transducer) over the skin. An ultrasound helps detect abnormal areas that might not be visible on a mammogram.
3. Breast Needle Biopsy
If an abnormal area is found, a needle biopsy is usually the next step. During this procedure:
- The breast is numbed.
- A radiologist uses a thin needle to remove a small sample of breast tissue.
- The tissue sample is examined under a microscope by a pathologist, who looks for signs of cancer cells and confirms the diagnosis.
Treatment for Invasive Lobular Carcinoma (ILC)
Treatment for invasive lobular breast cancer often involves a combination of approaches. Your care team will personalize your treatment plan based on the stage of cancer, hormone receptor status, and your overall health.
1. Surgery
Surgery is usually the first step and may include:
- Lumpectomy – removal of the tumor and a small margin of surrounding tissue.
- Mastectomy – removal of one or both breasts, depending on the size and spread of the tumor.
Your doctor may also remove nearby lymph nodes to check if the cancer has spread.
2. Chemotherapy
Chemotherapy may be given:
- Before surgery (neoadjuvant) to shrink the tumor and make it easier to remove.
- After surgery (adjuvant) to destroy any remaining cancer cells and lower the risk of recurrence.
3. Hormone Therapy
If your ILC is estrogen receptor-positive (ER+), hormone therapy can help block the effect of estrogen on cancer cells. This treatment is usually long-term and helps prevent the cancer from coming back.
4. Radiation Therapy
Radiation is often used after breast-conserving surgery to kill any leftover cancer cells in the breast or chest wall. It helps reduce the chance of recurrence.
5. Targeted Therapy
Targeted therapy focuses on specific genetic mutations that fuel cancer growth. Unlike chemotherapy, it attacks only cancer-related changes in cells, causing less damage to healthy tissue.
Other Types of Breast Cancer
In addition to ductal carcinoma in situ (DCIS), there are several other types of breast cancer. Each has distinct features, treatment approaches, and outcomes. These include:
- Triple-Negative Breast Cancer:
Triple-negative breast cancer lacks estrogen, progesterone, and HER2 receptors, making it more aggressive and harder to treat.
- Inflammatory Breast Cancer:
Inflammatory breast cancer is a rare but fast-growing cancer that causes redness and swelling, often without a lump.
- HER2-Positive Breast Cancer:
HER2-positive breast cancer overexpresses the HER2 protein, leading to rapid cancer cell growth.
- Metastatic Breast Cancer (Stage IV):
Metastatic breast cancer is breast cancer that has spread beyond the breast to other parts of the body.
- Metaplastic Breast Cancer:
Metaplastic breast cancer is a rare form that involves a mix of cell types and is often triple-negative.
- Mucinous Carcinoma:
Mucinous carcinoma is a slow-growing cancer made up of mucus-producing cancer cells.
- Invasive Ductal Carcinoma:
Invasive ductal carcinoma is the most common type, starting in the milk ducts and invading nearby tissues.
- Secondary Breast Cancer:
Secondary breast cancer, also called recurrent or advanced breast cancer, is cancer that returns or spreads after initial treatment.
- Fungating Breast Cancer:
Fungating breast tumors are uncommon tumors that break through the skin of the breast, often forming open wounds.
The Importance of Participating in Breast Cancer Research
Breast cancer clinical trials are essential for finding better treatments. They test new treatments and help doctors learn what works best. For example, ongoing Metastatic breast cancer trials continue to explore advanced options, offering hope for patients facing the most challenging stage of the disease.
Conclusion:
In conclusion, invasive lobular carcinoma (ILC) is a distinct and often hard-to-detect form of breast cancer that requires timely diagnosis and treatment. To help advance care, patients may also consider participating in paid research studies focused on better therapies and long-term solutions.
Frequently Asked Questions
What is a Lobular Mass in the Breast?
A lobular mass in the breast is a growth that originates in the lobules—the glands that produce milk. It may be benign or malignant, such as invasive lobular carcinoma, and typically requires imaging and biopsy for diagnosis.
What is the Survival Rate for ILC Cancer?
According to a 2024 study, the 5-year survival rate for invasive lobular carcinoma (ILC) is 88.6%, while the 10-year survival rate is 73.6%.
What are the Early Signs of ILC?
Early signs of Invasive Lobular Carcinoma (ILC) may include breast dimpling, thickening, swelling, or nipple changes like inversion or discharge. Unlike other cancers, ILC often doesn’t form a clear lump and may feel like a firm or thickened area.
Is ILC Hereditary?
Invasive Lobular Carcinoma (ILC) can be hereditary in some cases, especially when linked to inherited gene mutations like BRCA1 or BRCA2. However, not all ILC cases are inherited.
How ILC Differs from Invasive Ductal Carcinoma (IDC)?
While Invasive Ductal Carcinoma (IDC) starts in the milk ducts and often forms a noticeable lump, ILC spreads in a thin, single-file pattern throughout the breast tissue. This makes it less likely to form a distinct mass, and therefore, harder to detect early.
