Lobular Carcinoma in Situ (LCIS)

What is lobular carcinoma in situ (LCIS)?

Lobular carcinoma in situ (LCIS) is a rare condition that happens when you have abnormal cells in your lobules — the glands in your breasts that produce breast milk.

LCIS isn’t breast cancer even though its name includes the term “carcinoma” (cancer). The abnormal cells in your breast glands aren’t cancerous. They’re “in situ,” meaning they don’t become invasive cancer that’s spreading from your lobules to another part of your breast.

Having LCIS doesn’t mean you have a serious illness. But a diagnosis of LCIS does increase the chance that you’ll develop breast cancer later on.

LCIS types

Healthcare providers classify lobular carcinoma in situ by the way abnormal cells appear when viewed under a microscope:

• Classic LCIS: Tests show there are cells lining your lobules that are smaller than normal cells.
• Pleomorphic LCIS: Cells are larger than normal cells and look very different.
• Florid LCIS: Abnormal cells are forming a mass in your lobules. Tests may show an area of dead cells in the middle of the mass.

Is LCIS a common condition?

No, it’s not. It affects between 4 and 11 per 100,000 women and people assigned female at birth (AFAB). It’s even less common in men and people assigned male at birth (AMAB) — 1 in 100,000 people AMAB have LCIS.

What are the symptoms of lobular carcinoma in situ?

LCIS may not cause symptoms. For example, some people learn they have breast cancer after finding a lump in their breast that a test shows is a cancerous tumor. Instead, healthcare providers typically detect LCIS while viewing results from a breast biopsy done for another reason.

What causes LCIS?

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

What are the complications of LCIS?

While it doesn’t happen often, lobular carcinoma in situ may develop into ductal carcinoma in situ (DCIS) or lobular breast cancer. Studies show that 1 in 10 people with LCIS develop DCIS or lobular breast cancer. If you have LCIS, ask your provider to explain what you can expect.

How is LCIS diagnosed?

If test results show abnormal cells in your lobules, your healthcare provider may order another biopsy to find and remove any other abnormal cells. A pathologist will examine abnormal cells under a microscope to identify the type of LCIS that you have.

How is lobular carcinoma in situ treated?

Your treatment depends on the type of LCIS. 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 examinations and tests. For example, your healthcare provider may do a breast examination every six months. They’ll probably recommend that you have a mammogram every year. They may recommend additional tests, like a breast magnetic resonance imaging (MRI) scan.

Preventive therapy

As the name implies, preventive therapy is a treatment intended to keep abnormal cells in your lobules from becoming cancerous cells. Medications may include:

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

Surgery

If tests show you have pleomorphic or florid LCIS, your oncologist may recommend breast cancer surgery, including:

• Lumpectomy: This surgery removes abnormal cells and a small amount of healthy breast tissue.
• Prophylactic bilateral mastectomy: This surgery removes both of your breasts. Your provider may recommend mastectomy if an immediate family member, such as your mother, daughter or sister, had or has breast cancer.

Can LCIS be prevented?

Unfortunately, researchers don’t have enough information about LCIS to recommend ways to prevent it. But there are steps you can take to reduce your risk:

• Manage your weight: Having obesity increases your breast cancer risk.
• Get some exercise: Health providers typically recommend getting 150 minutes of moderate exercise per week. That’s 30 minutes, five days a week.
• Avoid beverages containing alcohol: Research shows a link between breast cancer and alcohol. The American Medical Association recommends women and people AFAB limit alcohol to one drink a day.
• Manage your medications: Hormone therapy or some types of birth control pills may increase your breast cancer risk. If you take hormone therapy or birth control pills, ask your healthcare provider to explain any risk you might have because you have LCIS. They may recommend that you change medications.

What can I expect if I have LCIS?

That depends on your situation, including the type of LCIS that you have. If you wonder what to expect, ask your healthcare provider to explain what’s going on in your breast and your treatment options. Understanding your options will help you feel more confident about your plan for living with LCIS.

How do I take care of myself?

There’s a lot you can do to take care of yourself if you have LCIS, like eating well, getting regular exercise and avoiding beverages that contain alcohol. Here are some other suggestions:

• Understand what changes in your breasts could be signs that LCIS is becoming a type of invasive breast cancer.
• Examine your breasts monthly. You might notice changes that have nothing to do with LCIS but could be signs of issues.
• Attend all follow-up appointments.

What questions should I ask my doctor?

Lobular carcinoma in situ is a rare condition that increases your risk of developing breast cancer. Understanding your risk and your options can help you feel more confident and in control of your situation. Here are some suggestions:

• What’s my risk of developing breast cancer?
• What are my treatment options?
• What are treatment side effects?

How long does it take for LCIS to become invasive?

LCIS may not become invasive breast cancer, but it can happen. When it does, it can take 10 to 15 years to happen. Even so, treatment often cures invasive breast cancer that started as lobular carcinoma in situ. For example, one analysis of LCIS cases shows that 98% of people who had surgery to treat LCIS were alive 10 years after treatment.