Invasive Lobular Breast Carcinoma

Invasive lobular carcinoma is the second most common type of breast cancer, accounting for 10 to 15 percent of all invasive breast cancers. Unlike other breast cancers that form lumps, this type grows differently, making it harder to detect but still treatable with proper diagnosis and care.

Table of contents

• What Is Invasive Lobular Carcinoma
• Where This Cancer Starts
• How Common Is This Type of Cancer
• Signs and Symptoms
• Who Is at Higher Risk
• Unusual Complications
• How Doctors Diagnose This Cancer
• Treatment Options

What Is Invasive Lobular Carcinoma

Invasive lobular carcinoma is a type of breast cancer that begins as a growth of cells in the milk-producing glands of the breast. These glands are called lobules, which are small, round sacs in the breast that produce milk for breastfeeding.^[1] The term “invasive” means that the cancer cells have broken out of the lobule where they began and spread into the surrounding breast tissue. The cells have the potential to spread to the lymph nodes and other areas of the body.^[1]

• Breast lobules (milk-producing glands)
• Breast tissue
• Lymph nodes

This cancer is different from other breast cancers in several important ways. In invasive lobular carcinoma, the cells lack the ability to “stick together,” a characteristic referred to as “cell-to-cell adhesion.” Because of this, the cancer does not form a mass the way other breast tumors do. Instead, the tumors may grow in what is called a “diffusely infiltrating” manner, or more simply, as lines of separate cells. Early on, these cells spread out in a single file to form strands or strings of cancer cells.^[3][15]

It is important to note that invasive lobular carcinoma is different from lobular carcinoma in situ (LCIS). LCIS is not cancer, while invasive lobular carcinoma is a true cancer that requires treatment.^[7]

Where This Cancer Starts

Invasive lobular carcinoma begins in the lobules of the breast. The lobules are the glands that make milk when breastfeeding. This location distinguishes it from the most common type of breast cancer, called invasive ductal carcinoma, which begins in the milk ducts rather than in the milk-producing glands.^[2]

How Common Is This Type of Cancer

Invasive lobular carcinoma makes up a small but significant portion of all breast cancers. It accounts for approximately 10 to 15 percent of all invasive breast cancers.^[2][3] An estimated 43,000 to 47,500 new cases of invasive lobular breast cancer are diagnosed every year in the United States.^[2][5]

Over the past two decades, the number of cases of lobular carcinoma has increased.^[2] This type of breast cancer affects an estimated 31,000 to 46,000 women in the United States each year.^[3] Invasive lobular carcinoma usually occurs in women who are older, with 68 percent of all new diagnoses occurring in women over the age of 60.^[5] The average age at diagnosis is three years greater than for invasive ductal carcinoma.^[9]

Breast cancer is very rare in men, and it is also very unusual for a man to have an invasive lobular type of breast cancer.^[7]

Signs and Symptoms

At first, invasive lobular carcinoma may cause no signs and symptoms. As it grows larger, it may cause noticeable changes in the breast.^[1] Because this cancer grows slowly and may not form a lump, it may not cause noticeable changes in the breasts for some time. You may have invasive lobular carcinoma for years before it’s seen on a mammogram or causes symptoms.^[3]

Invasive lobular breast cancer doesn’t always form a firm lump. Instead, you are more likely to have a thickened area of breast tissue.^[7] When symptoms do appear, they can include:

• A change in the texture or appearance of the skin over the breast, such as dimpling or thickening^[1]
• A new area of fullness or swelling in the breast^[1]
• An area of thickening in part of the breast^[1]
• A newly inverted nipple (a nipple that points into your breast instead of pointing out)^[1][3]
• A change in the nipple, for example it might turn inwards (become inverted)^[7]
• Breast pain or warmth^[3]
• Breast skin that looks or feels thicker than usual or has dimples, tiny dents or puckers^[3]
• Changes in breast size and shape, like an area of swelling or fullness^[3]
• Lump near your armpit^[3]
• Nipple discharge^[3]
• Skin discoloration that appears reddish or darker than usual^[3]

Make an appointment with a doctor or other healthcare professional if you notice a change in your breasts. Changes to look for may include a lump, an area of puckered or otherwise unusual skin, a thickened region under the skin, and nipple discharge.^[1]

Who Is at Higher Risk

Invasive lobular carcinoma happens when genetic mutations (changes) turn healthy cells into cancer cells. Experts aren’t sure what causes the mutations. Researchers believe the following factors increase your risk of having invasive lobular carcinoma:^[3]

• Being age 55 and older
• Giving birth after age 30 or not giving birth
• Having had breast cancer previously
• Having a family history of breast cancer or ovarian cancer
• Having lobular carcinoma in situ (LCIS)
• Inheriting certain genetic mutations
• Starting menopause later than usual (after age 55)
• Starting your period earlier than usual (before age 12)
• Receiving certain types of hormone therapy for menopause symptoms

Unusual Complications

Invasive lobular carcinoma may cause two unusual complications that make it different from other types of breast cancer:^[3]

First, it can spread to a larger-than-usual range of organs and tissues. While breast cancer that spreads (metastatic breast cancer) typically affects the brain, bones, liver and lungs, invasive lobular carcinoma may spread to those areas and also to less common areas, including:^[3]

• The digestive system, including the colon, small intestine and stomach
• Female reproductive organs, including the ovaries and uterus
• The leptomeninges (the lining of the brain and spinal cord)
• The peritoneum (lining of the abdomen)
• Tissues around the eye (orbital tissues)

Unlike invasive ductal carcinoma, which typically spreads to the lung, liver or bone, invasive lobular carcinoma has been found to spread to the gastrointestinal tract, peritoneum and retroperitoneum.^[6]

Second, you can develop metastatic invasive lobular carcinoma, which means it spreads to areas of your body far from your breast, 10 to 15 years after your diagnosis and treatment.^[3] A high level of suspicion is needed for metastatic breast cancer in patients with history of invasive lobular carcinoma, regardless of disease-free interval, since it frequently spreads to unusual sites and presents with a wide spectrum of symptoms.^[6]

How Doctors Diagnose This Cancer

Diagnosing invasive lobular carcinoma and other kinds of breast cancer often begins with an exam and a discussion of your symptoms.^[8] Your doctor may refer you to a breast clinic if you have any symptoms that could be due to invasive lobular breast cancer. You may also be referred to a breast clinic for tests if your screening mammogram shows an abnormal area.^[7]

At the breast clinic, the doctor or specialist nurse takes your medical history and examines your breasts. They also feel for any swollen (enlarged) lymph nodes under your arms and at the base of your neck.^[7]

You usually have a number of tests to check for breast cancer, including:^[7]

• Mammogram: A mammogram is an X-ray of the breast tissue. Mammograms are commonly used to screen for breast cancer.^[8] However, invasive lobular carcinoma is less likely to be detected on a mammogram than other types of breast cancer. This is because invasive lobular breast cancer doesn’t always form a firm lump, making it harder to detect. Still, a mammogram is a useful diagnostic test.^[8]
• Ultrasound: If you are under 35, you are more likely to have an ultrasound scan instead of a mammogram. Ultrasound uses sound waves to make pictures of structures inside the body. A breast ultrasound may give your healthcare team more information about a breast lump.^[7][8]
• Biopsy: A small sample of cells or tissue is taken from your breast and looked at under a microscope. To confirm whether there is cancer or not, a sample of tissue is removed from the breast for testing.^[7][8]
• Breast MRI scan: This imaging test can provide additional information about the breast tissue.^[7]

Under a microscope, invasive lobular cancer cells most often appear in a single file order. Because invasive lobular carcinoma tumors grow in this way, there may not be a mass (lump) present.^[20]

Treatment Options

The treatment for invasive lobular breast cancer is the same as for the more common type of breast cancer, known as invasive breast cancer No Special Type.^[7] Treatment is not based on whether the cancer is invasive lobular carcinoma, invasive ductal carcinoma or other tumor type. Treatment is based on breast cancer stage and other factors, such as the biomarkers hormone receptor status and HER2 status.^[20]

Invasive lobular carcinoma tends to be hormone receptor-positive and HER2-negative.^[20] This cancer usually grows in response to estrogen, the main female hormone. It grows slowly.^[3]

Your doctor considers many things before deciding the best treatment for you. Some of these factors include:^[7]

• The size of the cancer and whether it has spread (the stage)
• How abnormal the cells look under the microscope (the grade)
• Whether the cells have receptors for particular cancer drugs
• Your general health and level of fitness
• Whether you have had the menopause

This is why your treatment may be different from other people with breast cancer. Your doctor and breast cancer nurse will talk to you about your individual treatment plan.^[7]

The following treatment options are possible for invasive lobular breast cancer:

Surgery

You usually have either breast conserving surgery or a mastectomy. Breast conserving surgery removes the area of cancer and a surrounding area of healthy tissue. This operation is also called a wide local excision or lumpectomy.^[7]

Invasive lobular breast cancer is sometimes found in more than one area within the breast. In that case, it might not be possible to remove just the area of the cancer. Your doctor may then recommend removal of the whole breast, called a mastectomy.^[1][7] If you choose to, you can have a new breast made (breast reconstruction) at the same time as mastectomy or some time afterwards.^[7]

Compared to invasive ductal cancer, invasive lobular carcinoma is more likely to be multicentric (when there’s more than one tumor in the breast) and bilateral (when cancer occurs in both breasts).^[20]

You may also have surgery to remove the lymph nodes in your armpit. This is called a sentinel lymph node biopsy. This means having about 3 to 5 lymph nodes removed. Sometimes surgeons have to remove more lymph nodes. Your surgeon will let you know whether you need this.^[7]

Drug Treatments Before Surgery

You might have chemotherapy or hormone therapy before surgery. This is known as neo-adjuvant treatment.^[7]

Drug Treatments After Surgery

After surgery, you may need additional treatment, which can include:^[7]

• Chemotherapy
• Hormone therapy
• Targeted therapy
• Radiation therapy

Early diagnosis and treatment may cure invasive lobular carcinoma. But this cancer can spread to other areas of your body many years after your diagnosis and treatment.^[3]