International symposium focuses on lobular breast cancer

At the Pittsburgh meeting, advocates and scientists alike lauded Pate’s lobular legacy and how her efforts not only advanced research for this subtype, but increased support for patients with lobular breast cancer, many of whom feel alone and isolated after being diagnosed following years of “clear” mammograms.

“We’ve heard a lot about E-cadherin [a cell-cell adhesion molecule] and how lobular’s lack of this adhesion molecule keeps the cells from clumping together and making a lump,” said patient advocate Siobhan Freeney, founder of both Lobular Ireland and BeingDense.com. “Leigh Pate was our E-cadherin. She was the glue that held all of us together.”

In addition to honoring those lost to lobular, the ILC Symposium presented sessions on promising developments in imaging, new findings in liquid biopsy, potential new therapies and lingering old disparities. Patient advocates, who made up a third of attendees, organized sessions on the metastatic patient experience; connecting through social media; diversity, equity, inclusion and justice and more. There was even a yoga class. Read on for a brief roundup. 

What makes lobular different?

Lobular breast cancers are usually estrogen-receptor positive (ER+), so they’re treated similarly to ER+ ductal, now commonly referred to as NST (no special type) breast cancers. But in presentation after presentation, experts drilled down into important differences that distinguish lobular from other subtypes.

Chief of Breast Oncologic Pathology at Dana-Farber Brigham Cancer Center Stuart Schnitt, MD, highlighted these differences in his inaugural Leigh Pate Memorial Lecture, sponsored by the Dynami Foundation.

• Lobular is harder to find on physical examination and imaging. False negatives on mammograms are around 20% and the size of the tumors are often underestimated by mammogram and ultrasound.
• Lobular has important genomic differences: more frequent alterations in PTEN, TBX3, PIK3CA, FOXA1 in primary tumors and more frequent ERBB2 (HER2), especially in metastatic settings.
•  Lobular has a 3-fold lower prevalence of a high OncotypeDX recurrence score (used to determine if patients should receive chemotherapy) than ductal/NST cancers, but its 5-year disease-free survival rate is similar and its 10-year disease-free survival rate is lower.
• Lobular has low rates of pathological complete response (the disappearance of all cancer cells from the breast) after neoadjuvant, or pre-surgical, chemotherapy.
• More clinical trials are focusing on lobular now, including PELOPS, MutHER, GELATO and ROSALINE.

In closing, Schnitt emphasized that lobular breast cancers have many clinical, radiologic, pathologic and molecular features that distinguish them from common ductal/NST breast cancers and stressed the importance of accurately diagnosing lobular breast cancers. Many patients are initially misdiagnosed or diagnosed at later stages due to the imaging challenges.

One such woman was Claire Turner, founder of Lobular Breast Cancer UK, and one of the co-chairs of the symposium’s patient advocate organizing committee, dubbed the “GlobMob.”

“It took me five years to get diagnosed with lobular breast cancer after many clear mammograms, ultrasounds and biopsies,” said Turner, who along with others, presented a poster on the impact of delayed lobular diagnosis in women in the United Kingdom (i.e., England, Wales, Scotland and Northern Ireland). “Most people have never heard of lobular when they are diagnosed, so it’s incredibly important to get the message out.”

Lobular has (imaging) issues

Why is it hard to find and image this subtype?

Matthew Covington, MD, of Huntsman Cancer Institute in Salt Lake City broke it down in his presentation, citing ILC’s tendency to not cause anatomic changes (it may not make a lump); its penchant for metastasizing to unusual sites that can be difficult to image (think GI tract, peritoneum, ovaries) and its inability to take up glucose sufficiently (glucose is a common agent used in standard FDG-PET scans).

Another challenge: early-stage lobular patients can recur with metastatic disease up to 20+ years after treatment, thanks to tumor cells that escape from the breast then lie dormant elsewhere in the body until they’re “awakened” by something (researchers like Fred Hutch’s Cyrus Ghajar, PhD, are eager to learn what this something is).

Late recurrence holds true for ductal/NST breast cancers, as well, but it’s more common in lobular patients. Another big issue for these patients: dense breast tissue.

“Breast cancers are more difficult to detect in dense breasts on screening mammography,” Covington said. “And that’s even more true for invasive lobular carcinoma detection.”

Supplemental screening is definitely in order for those with dense tissue, he said, pointing to abbreviated breast MRI as a possible alternative (while acknowledging the cost and access issues associated with it). He also referenced the “Find It Early” Act, a proposed U.S. House of Representatives bill that would ensure all health insurance plans cover screening and diagnostic breast imaging, including mammograms, ultrasounds, breast ultrasounds and MRIs with no cost-sharing.

New imaging tools and techniques

But new imaging agents may change the lobular imaging landscape.

Fred Hutch breast oncologist and Breast Program Clinical Director Hannah Linden, MD, presented on these agents, in particular an estrogen-based radiopharmaceutical agent now used in FES-PET scans. Linden and others published key findings regarding its clinical utility which led to FDA approval of the tracer, marketed as Cerianna, in 2020.

“FES-PET scans offer us opportunities for much greater understanding of this disease,” she said, acknowledging that much like other imaging modalities, there are also challenges.

To illustrate, she compared the FES-PET’s capture of lobular breast cancer to an iceberg. A FES-PET can clearly image some common metastatic lesions, she said, including metastasis in bone, lung, lymph nodes, brain, retroperitoneal and uterine and ovarian areas. That’s the tip of the iceberg that everyone can see.

But other areas may not be as readily captured with FES-PET, she said, including metastasis in the liver, the gastric and/or intestinal area, the colon and the peritoneal cavity. They remain murkier, as if underwater.

“It’s harder to pick up lobular in small volume or when there’s sparse disease. And lobular grows as a net, another reason it’s hard to image,” said Linden, who holds the Athena Distinguished Professorship of Breast Cancer Research at the University of Washington. “That can be a real challenge. For all cancers, there’s an extent that we don’t ‘see,’ but for lobular tumors it’s greater. This is the work we need to do.”

Linden stressed that both FDG and FES-PET scans are clinically useful but said FES-PET had potential in predicting the benefit of endocrine therapy and modern therapeutics such as CDK 4/6 inhibitors.

“We have many endocrine options now,” she said. “FES-PET may identify patients who remain ER+ and thus potentially benefit from endocrine based therapy.”

Currently, the tracer for these scans is produced in 15 sites around the U.S. and imaging recommendations for it have been folded into the clinical practice guidelines for the National Comprehensive Cancer Network, a not-for-profit alliance of 33 leading U.S. cancer centers.

Director of Molecular Imaging and Therapy at Hoag Family Cancer Institute, Gary Ulaner, MD, PhD, said FES-PETs may soon be the “standard of care for imaging of lobular breast cancer.”

For now, though, the Society of Nuclear Medicine and Molecular Imaging recommends FES-PETs be used to select patients for endocrine therapy; to assess ER+ status in lesions that are difficult to biopsy and to solve clinical dilemmas after inconclusive results from conventional imaging. Full guidelines and recommendations can be found here.

Additional uses for the scan are being explored in clinical trials at Hoag and other locations. 

Liquid biopsy research and a new registry

Other presentations covered disparities in lobular breast cancer; the urgent need for new lobular cell lines and how exercise can help reduce inflammation, comorbidities and the side effects of cancer treatment — including lymphedema — in early-stagers and metastatic patients. Read more about lymphedema here.

Weill Cornell Medicine’s Chief of Breast Medical Oncology Massimo Cristofanilli, MD, FACP, spoke of the promise of liquid biopsies, a less invasive way to look for tumor cells.

“The field of liquid biopsy is changing our understanding of breast cancer clinical and molecular evolution,” he said. “Circulating tumor cell detection and molecular analysis is recognized as prognostic and predictive of outcome and identifies heterogeneity in expression and methylation of common biomarkers, such as HER2 and estrogen receptors.”

Director of the Institute for Precision Medicine at University of Pittsburgh Adrian Lee, PhD, shared research showing that circulating tumor cell counts are significantly higher in lobular than in ductal patients. Additionally, lobular circulating tumor DNA, or ctDNA, has “a higher number of pathogenic mutations compared to ductal ctDNA,” he said.

Clinicians and scientists alike pointed to the need for additional research to exploit these and other findings. Toward that end, the symposium’s poster session featured dozens of abstracts delving further into lobular liquid biopsies, treatment strategies, biomarkers, tumor microenvironment and more. Browse the complete ILC Symposium abstract booklet.

Penn Medicine’s Rachel Jankowitz, MD, called for new bespoke therapies.

“More research is needed to identify ILC-specific therapies that can translate into improved survival for patients with this disease,” she said. “Lobular breast cancer is a heterogenous disease and there will not likely be a ‘one-size-fits-all’ approach.”

Breast surgeon Rita Mukhtar, MD, of the University of California San Francisco, highlighted the disparities metastatic lobular patients face when trying to enroll in clinical trials, announcing a soon-to-be-launched registry, PLUMB, which will collect serial imaging, ctDNA and clinical assessments to better serve these patients.

“Clinical trials often require measurable disease,” she said. “If ILC is harder to measure, are patients with ILC being excluded from clinical trials?”

Fred Hutch’s Executive Vice President of Clinical Affairs Nancy Davidson, MD, who holds the Raisbeck Endowed Chair for Collaborative Research and was the former director of the University of Pittsburgh Cancer Institute and University of Pittsburgh Medical Center, moderated a panel of oncologists and surgeons discussing tricky lobular case studies. A final session looked at future research and clinical priorities.

Sharing stories and concerns

Seattle-area bookkeeper Gwen Manchion, 46, was one of many lobular patients who traveled east to participate and share her story. She found the symposium to be a huge learning opportunity.

“It offered a chance to meet clinicians and researchers interested in this less common form of invasive breast cancer,” she said. “It was such a great opportunity to be in the room with people working on this common goal. Imaging and disease monitoring are continued concerns; as well as the question of treatment to specifically address our disease, which behaves differently than other breast cancers.”

Many ILC patients closely follow the work of lobular researchers, she added, including Fred Hutch’s Linden.

“I've heard Dr. Linden speak on the issue of imaging lobular breast cancer several times and appreciate her continued interest and investment in this,” she said. “I was proud seeing providers from my home cancer center present in Pittsburgh. The lobular scientific and medical community have a huge fan base.”

Traveling while in treatment can be exhausting, but Manchion said the trip was worth it.

“I love putting a face on lobular breast cancer for researchers to keep in mind as they press forward to help improve our lives,” she said.

Editor’s note: Writer Diane Mapes was a featured speaker at the 2023 ILC Symposium, which covered her airfare and accommodations. She is also one of LBCA’s founding advocates.