An Overview of Invasive Lobular Carcinoma (ILC)

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Invasive lobular carcinoma (ILC) is a type of breast cancer that starts in the lobules of the breast, where milk is produced. At first, the cancer cells are found in the lining of the milk lobes, but later these cells infiltrate the nearby tissue outside of the lobes. ILC is a multi-focal cancer, which means there may be more than one area of cancer within the breast. It is also a bilateral cancer, which means it can affect both breasts. 

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Verywell / Nusha Ashjaee

Here's what you should know about invasive lobular carcinoma, including its prevalence, symptoms, causes, and treatment, and how to cope.


ILC is the second most common type of breast cancer after invasive ductal carcinoma (cancer that begins in the milk-carrying ducts and spreads beyond it). According to the American Cancer Society, 10 percent of all breast cancers are ILC.

ILC can affect women of any age, but is more often seen in women age 55 and older.

Signs and Symptoms

ILC cancers break though the wall of the lobule and start to invade breast tissues. Over time, ILC can spread to lymph nodes and other parts of the body. 

Early on, ILC does not usually cause symptoms. Sometimes, however, there is a thickening or hardening in the breast. Other symptoms may include:

  • Breast fullness
  • Skin texture changes
  • An inward nipple

ILC may also cause the symptoms seen in all types of breast cancer, which may include:

  • Swelling in all or part of the breast
  • Skin irritation
  • Breast and/or nipple pain
  • Nipple discharge other than breast milk
  • Lump in the underarm area
  • Breast or nipple skin that appears red, scaly, or thick

If you have any of these symptoms, it is a good idea to have them checked out by a health professional right away.


Researchers don’t have a clear idea of what causes ILC. They do, however, know that it starts when cells in one of the milk-producing glands start to develop DNA mutations. Mutations lead to an inability to control cell growth, causing cells to divide and grow quickly. If the cancer cells are aggressive, they can quickly spread to other parts of the body.

While the causes of ILC are unknown, there are known risk factors that might increase your chances of developing it.

  • Being female: Women are more likely to develop breast cancer, but men can also have breast cancer.
  • Age: The risk of ILC breast cancer increases as you age. Women with ILC are usually older than women who are diagnosed with other types of breast cancer.
  • Hormone use: Use of estrogen and progesterone during and after menopause can contribute to the development of ILC.
  • Genetics: Women who have certain inherited genes may have an increased risk for breast cancer.
  • Lobular carcinoma in situ (LCIS): LCIS is condition that causes abnormal cells within breast lobules. It is not a type of cancer, but it increases the risk for invasive cancer.


Diagnosing invasive lobular carcinoma requires a combination of steps, including a physical exam and imaging studies. Because ILC may affect multiple parts of both breasts, diagnosis involves examination of both breasts and surrounding tissues.

Physical Exam

Your healthcare provider may find areas in the breast that are thick or hard during a physical exam. Lumps are not usually felt with ILC.

Your practitioner may also feel the lymph nodes in the armpits to see if there is any swelling or abnormal changes. 


A mammogram creates X-ray images of the breast. Though it may be used, ILC doesn’t always show clearly on a mammogram because of the tendency of cells to grow in a single file line, rather than as a mass. If the mammogram does find ILC, the tumor may appear smaller than it really is.

Anytime a mammogram shows areas of concern, additional testing is done, including ultrasounds and magnetic resonance imaging (MRI).


Ultrasound bounces soundwaves off the breast to create images of breast tissue. It is usually used in conjunction with a mammogram because ultrasound offers more accuracy in detecting ILC. However, as with mammograms, on an ultrasound the tumor may appear smaller than it actually is.

Magnetic Resonance Imaging

An MRI uses a magnetic field to create pictures of the breast. A breast MRI is helpful for evaluating areas of concern when mammograms and ultrasound imaging are inclusive. An MRI can also help determine the extent and location of cancer in the breast. 

Breast Biopsy

To get a clear diagnosis of ILC, a breast biopsy must be performed to obtain a sample of the tissue for examination by a pathologist. A breast biopsy can determine the subtype of ILC under a microscope.

For example, the classic type, which is the most common, causes cells to line up in a single file. Other types, which are rarer, cause cells to grow in sheets; in groups of 20 or more cells; with structures; as large, differentiated cells; or as cells filled with mucus.


Once a diagnosis of ILC is made, your healthcare provider will determine if additional tests are needed for staging. Most of the time, imaging, the physical exam, and blood work offer enough information to determine the cancer stage a person is currently in.

Staging confirms that someone with cancer gets the best treatment. 

Staging is based on three main factors:

  • The size of the tumor and its growth into any areas around it
  • Spread of cancer to nearby lymph nodes
  • Spread of cancer to other parts of the body

Your healthcare provider will use this information to assign a Roman numeral to the appropriate stage. Breast cancer stages range from zero to IV, where stage 0 indicates a cancer that is small and invasive and stage IV is metastatic breast cancer, which means cancer has spread to other parts of the body.


Even through ILC is difficult to diagnose in comparison to other types of breast cancer, it is generally not aggressive. That means there is time to create a treatment plan to increase the chances of recovery.

Treatment options include surgery, chemotherapy, radiation, and hormone therapies, such as anti-estrogen therapy.


Surgical treatment varies depending on the stage of cancer. Small tumors are treated with a procedure called a lumpectomy, which involves removal of only part of the breast tissue. Mastectomy, on the other hand, involves having the entire breast removed. Any surgery (lumpectomy or mastectomy) also involves removal of at least some lymph nodes for evaluation, or possibly removing lymph nodes that are known to be involved with cancer.


Chemotherapy drugs kill cancer cells. Treatments usually involve two or more medicines in different combinations. Chemotherapy is given either in pill form, through a vein, or both. Sometimes, it is recommended after surgery to kill any cancer cells that remain. Chemotherapy may also be administered to help shrink a tumor prior to surgery.

Radiation Therapy

Radiation treatment involves the use of high-powered energy, including X-rays, to destroy cancer cells.

A radiation procedure involves lying down on a table while a large machine moves around you, directing energy beams to affected parts of the breast.

Hormone Therapy

Hormone therapy can be used to keep cancer from returning after surgery. If cancer has spread, hormone therapy may shrink and control tumors.  

Alternative and Complementary Therapies

There are no alternative medicine treatments that cure breast cancer. Instead, alternative treatments assist in coping with the symptoms and side effects of treatment.  

Many alternative therapies may hold great value, but there isn’t enough research regarding risks, benefits, side effects, and interactions with cancer treatment plans to confirm their efficacy or safety. However, research is expanding, and more and more healthcare providers are recommending alternative therapies to their ILC patients.

Some alternative treatments for cancer, such as acupuncture, have been researched. One small study from 2016 shows acupuncture may help relieve hot flashes caused by breast cancer treatments. Yoga, massage, and meditation have also been proven helpful for managing hot flashes.

Other alternative treatments may help with cancer treatment-related symptoms too. For example, ginger may be helpful for nausea relief.

Your healthcare provider is in the best position to create a treatment plan designed especially for your health and current situation. Talk to your healthcare provider before starting any alternative treatments for managing the side effects of cancer treatments.

Breast Cancer Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman


A diagnosis of ILC breast cancer is, no doubt, daunting. There is no right or wrong way to feel or act when it comes to your cancer diagnosis.

With time, it will get easier to cope with your feelings. You can help yourself by taking the following steps.

  • Educating yourself: The more you learn about ILC, the more comfortable you will feel as you make decisions about treatments and your overall health.
  • Seeking support: Your friends and family are a support system to help you cope. They can help with things you don’t have the energy to do on your own and listen when you need someone to talk to.
  • Connect with others with ILC: Other people with cancer can offer unique insight and support, because they understand what you are going through. Ask your healthcare provider about support groups or get in touch with your local American Cancer Society. There are also support groups online.
  • Take care of yourself: Take care of yourself by getting enough sleep, eating a diet full of healthy food options, staying physically active, and taking time to relax. Try to maintain your daily routine, including hobbies and social activities, as much as is feasible.

A Word From Verywell

The long-term outlook for someone with ILC depends on several things, including cancer stage, grade, and subtype; how close the cancer cells are to the tissue removed from the breast; a person’s age and overall health; and how well they respond to treatment. Another factor that may affect ILC outcomes is whether certain receptors (e.g., human epidermal growth factor receptor 2, or HER2) and hormones are found on the surface of cancer cells.

Early diagnosis and appropriate treatments are key to a good prognosis. Current survival rates for ILC are high, with the majority of people surviving five years post-diagnosis and staying cancer-free.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Cancer Society. Invasive Breast Cancer (IDC/ILC).

  2. Invasive Lobular Carcinoma (ILC).

  3. Signs and Symptoms of ILC.

  4. Breast Cancer Research Foundation. Invasive Lobular Breast Cancer: The Second Most Common Form of Invasive Breast Cancer is Understudied.

  5. Penn Medicine. Invasive Lobular Carcinoma Risks & Prevention.

  6. Tests for Diagnosing ILC.

  7. Makki J. Diversity of Breast Carcinoma: Histological Subtypes and Clinical Relevance. Clin Med Insights Pathol. 2015;8:23-31. doi:10.4137/CPath.S31563

  8. Penn Medicine. Staging Invasive Lobular Carcinoma.

  9. Local Treatments for ILC: Surgery and Radiation Therapy.

  10. Systemic Treatments for ILC: Chemotherapy, Hormonal Therapy, Targeted Therapies.

  11. Lesi G, Razzini G, Musti MA, et al. Acupuncture As an Integrative Approach for the Treatment of Hot Flashes in Women With Breast Cancer: A Prospective Multicenter Randomized Controlled Trial (AcCliMaT). J Clin Oncol. 2016;34(15):1795-802. doi:10.1200/JCO.2015.63.2893

  12. National Center for Complementary and Integrative Health. Cancer: In Depth.

By Pam Stephan
Pam Stephan is a breast cancer survivor.