Lobular Carcinoma in Situ (LCIS)

Lobular carcinoma in situ (LCIS) is a noncancerous breast condition that affects your lobules. These are the glands in your breasts that make breast milk. The abnormal cells are “in situ.” This means they don’t spread like cancer cells can.

LCIS isn’t breast cancer, but it’s important to know if you have it because it increases your future breast cancer risk. People with LCIS are seven to 10 times more likely to develop breast cancer than the general population. The risk applies to both breasts, not just the one with abnormal cells. Your overall breast cancer risk increases by about 1% to 2% each year.

Most people with this condition never develop breast cancer. If you have LCIS, frequent breast cancer screenings may find cancer early on, when it’s easier to treat. And there are treatments to reduce your risk.

LCIS types

Healthcare providers classify lobular carcinoma in situ by how the abnormal cells look under a microscope. The types are:

• Classic LCIS: Some abnormal cells fill and expand some lobules but stay inside them.
• Pleomorphic LCIS: More irregular, larger abnormal cells fill the lobules but stay inside them.
• Florid LCIS: Abnormal cells form a mass in your lobules. Tests may show dead cells in the middle of the mass.

Treatment varies based on the type.

Symptoms of lobular carcinoma in situ

It doesn’t cause symptoms. Unlike breast cancer, this condition doesn’t cause changes like a lump.

Instead, healthcare providers usually find the abnormal cells when viewing results from a breast biopsy done for another reason.

LCIS causes and risk factors

Researchers know that changes in your genes cause normal cells in your lobules to change into abnormal cells. But they don’t know what triggers the change.

Most people diagnosed are females in their mid-40s who haven’t gone through menopause. Males can get this condition, but it’s rare.

How doctors diagnose this condition

Lobular carcinoma in situ is almost always an “incidental” finding from a breast biopsy. This means that healthcare providers find the cells by chance while investigating another condition.

After they find LCIS, your healthcare provider may recommend more imaging or surgery to remove the area. This is especially the case if the biopsy and imaging results don’t fully match or if you have pleomorphic or florid LCIS.

How is lobular carcinoma in situ treated?

Your treatment depends on the type. For example, if you have classic LCIS, your healthcare provider may recommend active surveillance or preventive therapy. If you have pleomorphic or florid LCIS, you may need surgery.

Active surveillance

Active surveillance involves regular follow-up breast exams and tests. Your provider may do a breast exam every six to 12 months. You’ll likely need a yearly mammogram. They may recommend a breast MRI, which shows breast tissue in more detail.

Preventive therapy

Preventive therapy may keep abnormal cells from becoming cancer cells. Medications include:

• Selective estrogen receptor modulators (SERMs): You may have this treatment if you have an increased risk of ER-positive breast cancer.
• Aromatase inhibitors: Like SERMs, this is treatment if you’re at risk for ER-positive breast cancer.

Surgery

Your provider may recommend breast cancer surgery if tests show you have pleomorphic or florid LCIS. These types tend to grow faster than the classic type. Removing the cells and a section of healthy tissue makes sure no abnormal cells remain. Options include:

• Lumpectomy: This surgery removes abnormal cells and a small amount of healthy breast tissue.
• Bilateral mastectomy: This surgery removes both of your breasts. It’s rarely used to treat LCIS alone. But it may be an option to consider if you have a strong family history of breast cancer, a high-risk genetic mutation or other factors that significantly increase your cancer risk.

When should I see my healthcare provider?

Your provider will help you schedule regular breast exams. And don't forget to do monthly breast self-exams. Checking your breasts helps you find changes more easily. Let your provider know about any differences, like a new lump. The change may not be cancer. But if it is, catching it early makes it easier to treat.

Ask your provider about ways to reduce your breast cancer risk. They can advise you on lifestyle changes that may help.

What can I expect if I have LCIS?

That depends on your situation, including your age, family history and the type of LCIS that you have.

Most people with this condition never develop breast cancer. But LCIS does increase your risk over time. A recent study shows the percentages of women who developed cancer at 5, 10, 15 and 20 years after their diagnosis: 

• 5 years: 7%
• 10 years: 11%
• 15 years: 16%
• 20 years: 20%

Related, the lifetime breast cancer risk if you have LCIS is around 20%.

How long does it take for LCIS to become invasive?

LCIS usually doesn’t turn into invasive breast cancer. Instead, it’s a marker that your risk of developing breast cancer increases over time and can affect either breast. If cancer does develop, it can occur over many years rather than on a set timeline. When found early, it’s often highly treatable and may be curable.

What is the difference between DCIS and lobular carcinoma?

Lobular carcinoma in situ (LCIS) is a breast condition that affects your milk glands. Ductal carcinoma in situ (DCIS) is early-stage breast cancer in your milk ducts. Both involve cells that are unlikely to spread. But DCIS is a cancer while LCIS is not.

If you have LCIS, your risk of one day having DCIS is higher than average.