Lobular Breast Cancer

Lobular Cancer is different…

Lobular Breast Cancer is different from other breast cancers. Let’s talk about it…

Lobular carcinoma is the second most common form of breast cancer, representing only 10% to 15% of all breast cancers. The more common ductal carcinoma accounts for 80 - 85% of all breast cancers (Dana Farber Cancer Institute, 2025; Limaiem et al., 2023; Lobular Breast Cancer Alliance, 2025; The University of Texas MD Anderson Cancer Center, 2025; Napolitano, 2024). But Lobular is very different from the other breast cancers. 

There are important differences in presentation, behavior, spread, drivers, and visualizability in scans between lobular and ductal cancers, and lobular cancers’ unique characteristics have implications for diagnosis and treatment. Understanding these differences is critical in both management and treatment strategies. Because most breast cancers are ductal, breast cancer research and treatment plans historically have not distinguished between the two diseases, but these differences in how invasive lobular carcinoma behaves mean it needs different treatment. As of 2025, lobular is now recognized as a biologically distinct disease from invasive ductal carcinoma, and researchers are now studying ILC more closely (The University of Texas MD Anderson Cancer Center, 2025). However, conceptualizing this disease and the standard of care across the cancer care institutions is slow to catch up.

Lobular breast cancer is missing the protein E-Cadherin. As a result, lobular cancer cells are not cohesive and don’t cluster together or form lumps. It tends to spread out in either lines, sheets that marble through the tissues, or as scattered cells that are not attached to one another making it harder to feel during a breast exam, harder to detect in imaging scans of all types, and is often diagnosed at later stages (Napolitano, 2024; Limaiem et al., 2023; The University of Texas MD Anderson Cancer Center, 2025). Dr. Anita Mamtani of Memorial Sloan Kettering explains, “Lobular breast cancers are sneaky. Both their size and lymph node involvement tend to be notoriously underestimated on scans and during breast exams” (Napolitano, 2024).

When screening for or monitoring existing metastatic lobular breast cancer, regular PET/CT scans, MRIs, and Mammograms may not be very effective. FES PET CTs and 3D mammography better visualize this type of breast cancer, but it is still often missed (Dana Farber Cancer Institute, 2025; Limaiem et al., 2023). Lobular cancers are often poorly circumscribed and can even be missed on fine-needle aspirations and needle core biopsies (Napolitano, 2024).

Researchers have discovered that lobular cancer has different gene mutations than ductal cancer. This is especially important in stage 4 disease because certain treatments have been developed to target specific mutations (Barroso-Sousa, 2016; Limaiem et al., 2023). 

Invasive lobular breast cancer also differs in other ways. Lobular cancers are almost always hormone driven whereas ductal cancer can be hormone, HER2 positive, or triple negative and lobular tends to be less responsive to chemotherapy and more responsive to hormone therapies (Dana Farber Cancer Institute, 2025; Limaiem et al., 2023; Lobular Breast Cancer Alliance, 2025; Napolitano, 2024; The University of Texas MD Anderson Cancer Center, 2025).

It tends to recur in longer intervals (more than 10 years) after initial treatment (The University of Texas MD Anderson Cancer Center, 2025) and spread to all the same places that other hormone positive cancers spread to, but it also tends to go to more places in the body, that hormone driven ductal breast cancers generally don’t, such as the the brain (Dana Farber Cancer Institute, 2025). Spread to the leptomeningeal membrane around the brain is one of the rare but possible locations of the metastasis of ILC and there is a higher frequency of metastasis to the bone, gastrointestinal tract, uterus, meninges, ovary, lung and diffuse serosal involvement in Lobular than in Ductal (Limaiem et al., 2023: Napolitano, 2024).

Determining the extent of invasive lobular carcinoma is very important in deciding the treatment modality, but this is hard to do. The treatment of invasive lobular carcinomas has been a topic of debate due to its tendency to show up in both breasts, its lack of responsiveness to chemotherapy, and poor visualizability in scans. Even in surgery, it is difficult for surgeons and pathologists to find clear margins because the naked eye can’t see single cancer cells ( Limaiem et al., 2023). 

The multidisciplinary approach to the treatment includes surgery, radiation therapy, hormone therapy, and chemotherapy if appropriate, but if adequate preoperative investigations find no extensive or distant disease, conservative treatment excluding chemotherapy is often most appropriate for lobular carcinomas. Radiation therapy following breast surgery remains the standard of care. It decreases the incidence of recurrence within the breast but also improves overall survival (Limaiem et al., 2023; Napolitano, 2024).

Lobular Breast Cancer is simply different, and the public, physisicans and oncologists should be reeducated about how to screen for, diagnose and treat this disease.

“Throughout my almost 12-year cancer journey, I have been misdiagnosed repeatedly and had my diagnosis delayed on 3 separate occasions; twice at one of the best cancer hospitals in the nation, because the oncologists I was working with lacked basic awareness of the lobular cancer subtype. As recently as 2024, my symptoms were continuously dismissed because they were assessed against ductal cancer characteristics, not the unique characteristics of lobular cancer. This led to a 2-year delay in the diagnosis of leptomeningeal brain mets, leading to a dire outcome. At each one of my intervals with active cancer, despite repeated reports of symptoms to my doctors, I was told my symptoms didn’t track with hormone-positive cancer. This is a falsehood, and had my doctors understood lobular better, I very well could have been spared metastatic disease. I feel it is critical to shine a spotlight on this information to support others who have faced similar experiences, but also to draw attention to this issue, so that it doesn’t happen to anyone else”. - Stacy Withrow