Raising Awareness for a Less-Recognized Breast Cancer Subtype
Last week, lobular breast cancer patients and their providers gathered at Fred Hutch Cancer Center for a two-hour program timed to Global Lobular Breast Cancer Awareness Day. The event highlighted patient stories, epidemiological findings, and the latest developments in screening and clinical trials for invasive lobular carcinoma (ILC), the second most common breast cancer subtype. With 24 state governors issuing proclamations in support, the day underscored the growing focus on ILC as a distinct disease with its own challenges and research opportunities.
Why ILC Often Appears at a Later Stage
ILC has a reputation for presenting at more advanced stages, often with larger tumors and lymph node involvement. A key reason is its tendency to grow in a “lumpless” pattern, forming fewer obvious masses and making early detection harder through standard exams and imaging. This underdiagnosis means patients can present with more extensive disease when discovered.
Stefanie LeJeunesse, a patient advocate and educator diagnosed with metastatic lobular breast cancer at 39, shared a powerful account of diagnostic challenges. Despite multiple tests at a rural hospital, she was initially told her cancer was stage II with likely benign lymph nodes. A second opinion at Fred Hutch revealed a 2-centimeter primary tumor that had already spread extensively, including metastases to the spine and ribs. Her story illustrates the real-world consequences of diagnostic uncertainty in ILC.
What Elevates ILC Risk: Hormones, Alcohol, and Beyond
From an epidemiological perspective, researchers at Fred Hutch emphasize that ILC is highly hormonally driven. Dr. Christopher Li highlighted a striking rise in ILC rates, noting a 65% increase over a short interval compared with a 4% rise for all breast cancers. The Seattle-area SHARE study linked long-term combined hormone therapy (estrogen plus progestin) to significantly higher ILC risk, with some analyses showing risk increases up to fourfold in certain subgroups.
Alcohol also emerges as a consistent dietary risk factor, especially for lobular cancer. Large studies indicate that moderate-to-heavy drinking correlates with higher estrogen levels, a key driver for ER-positive ILC. Li cautions against long-term use of combined HRT and notes that some hormonal contraceptives (e.g., certain forms of Depo-Provera) may further elevate risk. These findings underscore the importance of personalized risk assessment in breast cancer prevention and screening strategies.
New Imaging and Trial Frontiers: Paving the Way for Better Outcomes
Clinical researchers are advancing both imaging and trial design to better capture ILC, particularly ER-positive disease. Dr. Hannah Linden highlighted the FDA-approved FES-PET tracer, which targets estrogen receptors and offers an alternative to the traditional FDG-PET, helping to stage and monitor lobular disease more accurately. This tracer is especially useful for enrolling patients in trials, including those with bone metastases who were previously excluded due to lack of measurable disease under older criteria.
Beyond imaging, researchers are refining how response is measured in lobular cancers. RECIST criteria focus on measurable tumor size, but PERCIST (PET-based response criteria) could expand eligibility for trials by recognizing bone-dominant disease. Linden also emphasized the need for better diagnostic workups, noting that many patients in Washington state are underdiagnosed and that biopsy remains crucial for accurate staging in ILC due to its stealthy spread pattern.
Looking to the pipeline, several trials target ER+ ILC specifically, including endoxifen trials for premenopausal patients and PET/CT studies for progesterone receptor-positive tumors. Researchers are also exploring KAT6 inhibitors and FAPI-based theranostics that combine targeted imaging with radioactive therapy. Linden framed these efforts as part of a broader shift toward precision oncology with fewer toxicities than traditional chemotherapy.
The Human Side and Practical Takeaways
Patient voices at the event reinforced the reality that access to experts, imaging, and trials matters. LeJeunesse urged patients to seek care at NCI-designated centers where expertise is concentrated, noting that diagnostic quality can bear directly on outcomes. The Q&A session emphasized cautious use of combined HRT and awareness of alcohol’s impact on breast cancer risk, particularly for those with a family history or ER+ tumors.
As researchers push ahead with novel imaging tools and targeted therapies, the lobular cancer community remains hopeful about a future where early detection is more reliable, diagnostic workups are standard, and treatments are personalized with fewer side effects. The day’s discussions exemplified a growing commitment to turning this subtype of breast cancer into a story of improved outcomes and expanded access to cutting-edge care.
