Invasive lobular carcinoma is a common type of breast cancer that can spread to other parts of the body. Early diagnosis and treatment can help improve the long-term outlook for this condition.

Also known as infiltrating lobular carcinoma or lobular breast cancer, invasive lobular carcinoma (ILC) is cancer in the milk-producing glands. People with ILC are unlikely to feel the telltale lumps.

ILC grows and spreads differently from other breast cancers like invasive ductal carcinoma (IDC), or cancer of the milk ducts.

When cancer spreads, it’s called metastatic. In ILC, the cancer starts in the breast lobules and move to the surrounding breast tissue. It can also travel to lymph nodes and other organs in the body.

It’s estimated that nearly 298,000 women in the United States will receive an invasive breast cancer diagnosis in 2023. ILC makes up about 10% of those diagnoses.

Sex and gender exist on spectrums. This article uses the term “women” to refer to a person’s sex assigned at birth.

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ILC develops differently from more common types of breast cancer. It’s less likely to have obvious lumps. In the early stages, there could be no signs or symptoms. But as the cancer grows, you may notice your breasts:

  • thickening or hardening in a certain area
  • swelling or feeling full in a certain area
  • changing in texture or skin appearance, such as dimpling
  • developing a newly inverted nipple
  • changing in size or shape

Other signs may include:

  • breast pain
  • nipple pain
  • discharge other than breast milk
  • a lump around the underarm area

These are usually the first signs of breast cancer, including ILC. See a doctor if you notice these signs or symptoms.

What causes ILC is unclear. However, this type of cancer starts when the cells in your milk-producing glands form a DNA mutation that normally controls cell growth and death.

The cancer cells start dividing and spreading out like branches, which is why you’re unlikely to feel a lump.

Several factors can increase the risk of developing ILC, including:

Lobular carcinoma in situ (LCIS)

Your risk of developing ILC may increase if you’ve had an LCIS diagnosis. LCIS is when atypical or abnormal cells are found, but these cells are confined to the lobules and haven’t invaded surrounding breast tissue.

LCIS isn’t cancer and is considered an uncommon condition.

Doctors use several different imaging tests to help diagnose lobular breast cancer. These tests include:

ILC has a few subtypes, which are based on the appearance of the cells under the microscope. In the classic type of ILC, the cells line up in a single file.

Other less common types of growth include the following:

  • Solid: grow in large sheets
  • Alveolar: grow in groups of 20 or more cells
  • Tubulolobular: some cells are single-file formation and some form tube-like structures
  • Pleomorphic: larger than classic ILC with nuclei that look different from each other
  • Signet ring cell: cells are filled with mucus


Mammograms can give false-negative results for lobular cancer. This is because, in an X-ray, lobular cancer looks similar to normal tissue.

ILC also spreads through the breast tissue differently from IDC.

Well-formed tumors and calcium deposits aren’t as common, making it hard for a radiologist to distinguish ILC from normal breast tissue on a mammogram.

It’s also more likely to develop in more than one area of the breast or in both breasts. If it’s seen on a mammogram, it may appear smaller than it actually is.

Staging ILC

Breast cancer staging is when a doctor determines how advanced the cancer is or how far it has spread from the breast.

Staging is based on:

  • the size of the tumor
  • how many lymph nodes have been affected
  • whether the cancer has spread to other parts of the body

There are four stages of ILC, from 1 to 4.

Like IDC, if ILC spreads, it tends to show up in the:

Unlike IDC, ILC is more likely to spread to unusual places like the:

  • stomach and intestines
  • abdomen lining
  • reproductive organs

To determine whether the cancer cells have spread, a doctor may order tests to check your lymph nodes, blood, and liver function.

Your best treatment option will depend on your cancer stage, age, and general health. Treating ILC usually involves surgery and additional therapy.

Choosing your surgeon carefully is especially important because of ILC’s unusual growth pattern. A surgeon with experience in treating patients with ILC is key.

Less aggressive surgeries like lumpectomy have similar results to aggressive treatments like a mastectomy.

A lumpectomy may be a good option if only a small portion of the breast has cancer. In this surgery, the surgeon only removes the cancer tissue.

If more breast tissue is involved, a doctor may recommend a mastectomy, or complete breast removal.

Other options include removing lymph nodes near your breast, a procedure called sentinel lymph node biopsy, and armpit, which is known as axillary lymph node dissection.

You may need additional treatment, such as radiation, hormonal therapy, or chemotherapy, to reduce the risk of the cancer growing back after surgery.

Complementary and alternative treatments

While complementary and alternative medicine (CAM) treatments aren’t known to cure breast cancer, they can help relieve some of the symptoms and side effects of cancer and its treatments.

For example, people taking hormone therapy for breast cancer can experience hot flashes, or sudden, intense warmness, and sweating.

You may find relief through:

Always talk to a doctor before trying a new medication or supplement. They may interact with your current treatment and cause unintended side effects.

Hormone therapy (HT) may be recommended if your cancer cells are sensitive to hormones like estrogen and progesterone.

This is usually the case in lobular breast cancer. HT can block your body’s hormones from signaling the cancer cells to grow.

Lobular carcinoma, like other breast cancers, can develop in otherwise healthy individuals. You can reduce your risk by:

If you’re considering HRT, discuss the risks and benefits of this therapy with a doctor. HRT may raise the risk of lobular carcinoma and other types of breast cancer.

If you do choose to take HRT, you should take the lowest effective dose for the shortest possible time.

Getting a breast cancer diagnosis of any type can be overwhelming. Learning about breast cancer and the treatment options may help you feel more at ease as you move through your journey.

Places you can turn to for support if you’re diagnosed with lobular breast cancer include:

There’s an increased risk of developing invasive breast cancer if you’re diagnosed with LCIS. You can take medications, like tamoxifen, to lower your risk.

A doctor may also suggest a mastectomy if you have a family history of breast cancer.

The breast cancer community is a visible and vocal one. Local support groups may be helpful in connecting you with others who are going through similar experiences.

Early diagnosis and advances in treatment help increase your chance of living a long and healthy life. The long-term outlook of ILC depends on multiple factors, such as:

  • the stage of cancer
  • grade and subtype
  • surgical margins, or how close the cancer cells are to the tissue removed from the breast
  • your age
  • your overall health
  • how well you respond to treatment

Another factor that affects outcome in ILC is whether estrogen, progesterone, or HER2 (human epidermal growth factor receptor 2) receptors are found on the surface of the cancer cells.