Breast oncologist Dr. Sherry Shen is a co-director of MSK’s new program focused on lobular breast cancer, which behaves and grows differently than other types of breast cancer.
A type of breast cancer that can be difficult to detect and challenging to treat is the focus of a new program at Memorial Sloan Kettering Cancer Center (MSK). Known as lobular breast cancer (LBC), it’s the second most common breast cancer.
“This kind of breast cancer has its own unique features, which require a different approach to screening, diagnosis, and treatment,” says MSK breast oncologist Sherry Shen, MD.
Dr. Shen, MSK breast surgeon Anita Mamtani, MD, and MSK breast pathologist Fresia Pareja, MD, co-direct the new Lobular Breast Cancer Program at MSK. Their goal is to improve outcomes for people with LBC and conduct more research into the biology of the disease.
Drs. Shen and Mamtani answer common questions about lobular breast cancer and discuss essential differences in diagnosis and treatment.
What is lobular breast cancer and how common is it?
LBC, also known as invasive lobular carcinoma, forms in the lobules, which are the small round sacs that make breast milk. LBC accounts for about 15% of all breast cancers. This year, more women will be diagnosed with LBC than ovarian and cervical cancer combined.
The most common type of breast cancer is invasive ductal carcinoma, or ductal breast cancer (DBC). It accounts for nearly 80% of breast cancer cases.
How is lobular breast cancer different than ductal breast cancer?
The biggest difference is that DBC forms in the ducts that carry breast milk to the nipple, whereas LBC forms in the lobules that make breast milk. There are also differences in the symptoms and growth patterns of these two breast cancers.
Lobular breast cancer cells don’t stick together and form a tumor like DBC and other breast cancers. Instead, they tend to grow in a line, in sheets, or as scattered cells that aren’t attached to one another.
What are the symptoms of lobular breast cancer?
“People with LBC might feel a vague sensation, fullness, engorgement, or firmness in their breasts, or notice redness, skin or nipple changes, or discharge from the nipple,” says Dr. Mamtani. “Those are the most common signs in patients with an advanced lobular breast cancer that’s been hiding in their breast for a long time.”
When LBC is caught early, most people will have no symptoms, adds Dr. Mamtani.
Ductal breast cancer, however, often forms a lump that’s visible on a screening mammogram and sometimes felt during a breast exam.
Are lobular breast cancers harder to detect?
“LBC grows in a way that’s not cohesive, so people are less likely to feel a mass or nodule, and it’s not easily detected on screening mammograms,” says Dr. Shen. “As a result, some people are diagnosed at a later stage when the tumor is bigger.”
MSK breast surgeon Dr. Anita Mamtani
“Lobular breast cancers are sneaky,” adds Dr. Mamtani. “Both their size and lymph node involvement tend to be notoriously underestimated on scans and during breast exams.”
This means that a tumor may be larger, and that the cancer may have spread to more lymph nodes than what was initially seen on mammography.
Despite this characteristic of LBC, with appropriate screening, most lobular cancers can still be detected at an early stage.
Using additional screening tools like ultrasound, contrast enhanced mammogram, or MRI can more accurately detect LBC. However, those tests aren’t typically ordered until symptoms are reported, or a suspicious area is detected during breast cancer screening.
How is lobular breast cancer treated?
Treatment guidelines for LBC are often based on research done in people with DBC. Recognizing the need to refine treatment approaches for LBC was a key reason MSK created the new program.
“We treat our patients using the latest imaging technology, surgical techniques, radiation and drug therapies, and clinical trials,” says Dr. Shen. “We know each case is different, and our experts will make sure people with LBC get the most specialized and up-to-date care.”
Currently, LBC that has spread and progressed to stage 4 is also treated the same as DBC.
Stage 4 breast cancer requires treatment with oral medications or intravenous therapies that go through the whole body to target breast cancer cells wherever they are. Treatment needs to be ongoing to shrink the cancer and keep it under control.
“This is where there’s a lot of innovation happening,” notes Dr. Shen. “There’s an urgent need to develop new treatments that improve upon our standard of care.”
For example, researchers have discovered that LBC has different gene mutations than DBC. This is especially important in stage 4 disease because certain treatments have been developed to target specific mutations.
MSK uses a genetic test called MSK-IMPACT® to find mutations and other critical changes in tumors that other tests can miss. Doctors can quickly find out whether a cancer will respond to certain treatments.
Is the prognosis for lobular breast cancer similar to other types of breast cancer?
“It’s unclear whether the survival rates for lobular breast cancer are all that different from ductal breast cancer, because there are so many different factors,” says Dr. Shen.
MSK medical oncologist Dr. Sherry Shen
A major factor is the stage at diagnosis. The lower the stage, the less likely the patient will have a recurrence. Stage 3 has the highest risk of the cancer returning. Lobular breast cancer can recur much later than the ductal type, often many years after the primary diagnosis.
When LBC affects areas of the body outside the breast, the biology and spreading pattern are unique. Because lobular cancer cells don’t tend to clump together, they can spread along the linings of organs, such as the ovaries, the uterus, the gastrointestinal tract, and even the lining of the brain and spinal cord. In contrast, ductal cancers don’t tend to spread to those organs and instead form distinct tumors.
A very small number of people — 5% or less — are initially diagnosed with stage 4 disease.
Is lobular breast cancer always invasive?
According to Dr. Mamtani, there is no such thing as “noninvasive cancer.”
“Cancer is, by definition, an invasive process capable of spreading and moving through the breast and to other parts of the body,” she explains. “The fact that a cancer is localized in the breast at the time of diagnosis doesn’t make it noninvasive. It means that it has been caught at an early stage, but still warrants prompt and comprehensive evaluation and treatment.”
What are the “in situ” growths in the breast that are noninvasive?
There are precancerous breast conditions found in the ducts, which are called “in situ” and are not invasive. For example, ductal carcinoma in situ (DCIS) is stage 0, with no potential to spread beyond the breast.
On the other hand, LBC that is diagnosed at stage 1, 2, 3, or 4 is invasive and requires treatment. A breast biopsy can determine whether a breast tissue sample contains precancerous or cancerous cells.
A number of noncancerous conditions grouped under the term lobular neoplasia, such as atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS), can raise a person’s risk for getting cancer.
“Lobular neoplasias are not a precursor to cancer,” says Dr. Mamtani. “We do not remove them, but it means that a person is at higher risk of getting breast cancer. They should be monitored with a good screening plan, and may be offered medications to reduce their risk of breast cancer.”
What are other types of lobular breast cancer?
LBC has several subtypes. These include:
- Pleomorphic LBC, which is rare but considered aggressive.
- Invasive ductal carcinoma-lobular (IDC‐L) is a “mixed” version in which people have both DBC and LBC.
- Bilateral LBC, which occurs when people are diagnosed with LBC in both breasts. LBC has a slightly higher likelihood of developing in both breasts compared to DBC.
Why should people with lobular breast cancer come to MSK?
Because MSK’s breast cancer experts across all specialties — including surgeons, radiologists, radiation oncologists, pathologists, and medical oncologists — focus only on breast cancer, they’re able to work together to create personalized treatment options for every patient. This includes clinical trials that offer people with LBC the chance to access treatments that are not available at other hospitals.
“That’s another reason to come to MSK, especially if you have stage 4 lobular breast cancer,” says Dr. Shen. “We can do genetic testing of your cancer to learn what those unique genetic mutations are and use that information to possibly match you to clinical trials that will benefit you most.”
Adds Dr. Shen, “There’s a different biology behind lobular breast cancer, and different genetic characteristics. As we develop new clinical trials specific to lobular breast cancers and their genetic profiles, we will learn how to treat them more precisely.”