Global Lobular Breast Cancer Day shines spotlight on ILC challenges and breakthroughs
Last week, invasive lobular breast cancer (ILC) patients and their care teams gathered at Fred Hutch Cancer Center for a focused two-hour program. The event, held on October 15 to mark Global Lobular Breast Cancer Awareness Day, brought patient stories, epidemiological insights, and the latest developments in screening and clinical trials for this common breast cancer subtype. Across the U.S. and in many parts of the world, the day has inspired state proclamations and renewed attention to a cancer subtype that accounts for about 15% of breast cancer diagnoses each year.
During the event, Fred Hutch experts and patient advocates explored how ILC is changing the landscape of breast cancer research and care. The American Cancer Society released its first report detailing the occurrence and outcomes of ILC, underscoring a concerning rise in rates in recent years.
Why ILC often shows up at later stages
Radio-oncologic imaging specialist Diana Lam, MD, explained that ILC frequently presents without a palpable lump. As a result, tumors can be less conspicuous on clinical exams and some imaging modalities, delaying diagnosis and potentially allowing progression to more advanced stages with broader lymph node involvement.
Stefanie LeJeunesse, a metastatic lobular breast cancer survivor who spoke at the event, recounted her experience with diagnostic delays. After initial testing—including mammography, ultrasound-guided biopsy, MRI, and a bone scan—she was told her cancer was stage II with limited nodal involvement. A second opinion later revealed a far more extensive disease, with a 14-centimeter spread and multiple metastases. Her message was clear: second opinions can be life-changing for those with suspected ILC.
Epidemiology and hormonal drivers of ILC
epidemiologist Christopher Li, MD, PhD, discussed how the incidence of ILC has risen more sharply than other breast cancer subtypes. A landmark 2000 finding linked hormone exposure to lobular risk: combined hormone replacement therapy (HRT) roughly doubles the risk of ILC, with longer use amplifying this risk. The Seattle-area Hormones And Reproductive Epidemiology study (SHARE) further showed that longer, combined HRT use could quadruple ILC risk in some populations. Li noted that at the peak of HRT usage, an estimated 30–40% of U.S. women were using hormone therapy, highlighting a historic public health exposure that disproportionately affected lobular cancers.
Other hormonal factors emerged as contributors, including alcohol consumption. Large studies found that alcohol notably raises estrogen levels and carries a higher relative risk for ILC than for ductal breast cancer. The take-home, Li said, is that ILC is a highly hormonally sensitive cancer, where lifestyle and hormonal therapies intersect with tumor biology.
Screening, diagnosis, and evolving trial designs
Hannah Linden, MD, of Fred Hutch, highlighted advances in imaging and trial inclusion criteria. The FDA-approved FES-PET tracer binds estrogen receptors and has become a valuable tool for identifying candidates for endocrine therapies and enrolling patients into trials who might otherwise be deemed ineligible due to non-measurable disease. While traditional FDG-PET remains useful for certain assessments, FES-PET addresses the hormone-driven nature of ILC and can help capture bone-dominant disease for trial participation.
Linden also clarified that ILC can metastasize to organs like bone, lung, lymph nodes, brain, and even peritoneal surfaces, which demands a broader diagnostic approach. She cautioned that standard diagnostics sometimes underfund workups for ILC, noting under-diagnosis issues in some settings and calling for more consistent biopsy practices in suspected metastatic disease.
Trials on the horizon: targeted therapies and precision care
Looking ahead, several clinical trials hold promise for ER-positive lobular patients. The Evangeline trial will study endoxifen in premenopausal women, while FFNP PET/CT investigations will evaluate progesterone receptor–positive tumor imaging. Additional studies are exploring KAT6 inhibitors, fibroblast activation protein inhibitors (FAPI), and theranostic approaches that combine diagnostic imaging with targeted radiotherapy. Linden described FAPI as a potentially transformative avenue for lobular cancer, aiming to map the tumor microenvironment and deliver targeted treatments with minimized toxicity.
These advances align with a broader shift in cancer care toward endocrine-based strategies and targeted therapies that may reduce reliance on traditional chemotherapy for ER-positive tumors. The overarching message from the event was hopeful: as detection improves and therapies become more precisely tailored, patients with ER+ lobular cancers may experience better outcomes with fewer side effects.
Voices from the patient community: a call for access and consistency
In a Q&A, experts emphasized avoiding risky combined HRT for people diagnosed with ER+ breast cancer and highlighted alcohol’s damaging effects on lobular risk. A poignant takeaway from patient stories was the variability in diagnostic infrastructure across regions. LeJeunesse urged patients to seek care at reputable, often NCI-designated, centers to ensure access to the latest screening, diagnostics, and trials. The event underscored the importance of ongoing education for both patients and clinicians to close gaps in diagnosis and care for ILC.
Conclusion: a turning point for lobular cancer care
Global Lobular Breast Cancer Awareness Day events like this Fred Hutch gathering emphasize that lobular cancer is not a rare or static disease. With rising incidence, evolving imaging, and a growing pipeline of targeted trials, there is reason for optimism. As researchers expand our understanding of ILC biology and refine diagnostic and treatment pathways, patients can look forward to earlier detection, more precise therapies, and improved quality of life.
