SNMMI Mars Shot: Lobular Breast Cancer

Invasive Lobular Carcinoma (ILC) or Lobular Breast Cancer represents 15% of all breast cancer diagnoses afflicting over 43,000 women/year annually in the U.S. alone. ILC tumors can be more difficult to identify on imaging studies and by physical exam because many lack the protein e-cadherin, which causes an unusual linear growth pattern and not lumps. In fact, many studies have shown decreased accuracy of breast imaging tools for ILC, and those with ILC are often diagnosed at later stages and require more extensive surgery. ILC tumors also can metastasize to unusual parts of the body and progression is often hard to view and monitor with imaging methods. 

In a survey conducted by over 1,400 women with lobular breast cancer conducted by the Lobular Breast Cancer Alliance LBCA in 2021, 67% of respondents indicated having a tumor larger than 2cm at diagnosis, and 63% reported stage two or higher, including 5% at stage four at initial diagnosis. Many participants also reported that the actual tumor size on the final pathology specimen was larger than seen on diagnostic imaging. Results confirmed patients’ perceptions of mammography as an imperfect screening tool to detect ILC. 

Breast cancer deaths in women occur primarily when it has metastasized and spread to other organs, such as the brain, lungs, or bones. The risk of later recurrence and metastasis increases when initial breast cancer tumors are not found until they are larger and/or later stage.

Despite these troubling characteristics of ILC and the fact that ILC is a relatively common cancer in women, there has been very little research on ILC and research into better detection or monitoring methods for ILC specifically has not occurred. These very troubling characteristics of lobular breast cancer and the insufficiency imaging tools for imaging for both initial detection and detection and monitoring of metastatic ILC are a critical problem.

The need for better mechanisms for detecting and monitoring ILC is a top research priority for the Lobular Breast Cancer Alliance and its Patient Advocate and Scientific Advocate advisory boards this year. Only by finding better methods for detection and monitoring changes in ILC tumors, can more effective treatments for ILC be developed and metastatic ILC stopped.


Investing in the research and implementation of new nuclear medicine imaging procedures can help identify ILC tumors and their changes better. There is the potential for better mechanisms that will more effectively: 

  • Stage the ILC and determine the presence or spread of cancer in various parts of the body
  • Determine the presence of ILC in sentinel lymph nodes before surgery
  • Detect recurrence
  • Evaluate ILC tumor response to therapies

There are already some new mechanisms that hold promise for ILC but which have not yet been studied extensively for efficacy in these areas specifically for ILC tumors. These include radiotracers such as 18F-fluoroestradiol (FES), which enable physicians to accurately identify estrogen-positive disease on a whole-patient level. Since the majority of ILC tumors are estrogen-positive it is important to further study how these radiotracers might be used in the staging and monitoring of ILC tumors. Studying other mechanisms of imaging or combined systems of imaging in examining lobular breast cancer is also critical to the ultimate identification of precision therapies for lobular patients.


PET: A way to provide functional information by injecting a tiny amount of radiotracer into a patient’s bloodstream and then imaging its distribution.
PET/CT: A combined imaging study providing detail on both the precise anatomy (CT) and the metabolic function (PET) of organs and tissues, by superimposing the two types of images.
Radiotracer or radiopharmaceutical: A drug molecule combined with a minute quantity of radioactive material that localizes in specific organs or areas of the body and can be detected by an imaging device like a PET scanner.


Harnessing the power and precision of molecular imaging and therapy has the potential to increase quality of life for patients with lobular breast cancer. Nuclear medicine offers less invasive, more specific, and adaptable treatments to create better overall outcomes. The Lobular Breast Cancer Alliance in collaboration with SNMMI intends to issue a request for applications and issue a grant award this year for an ILC imaging study that helps advance the knowledge of how best to detect and treat ILC tumors. Patients with ILC are a population where substantial impact is possible”, says Dr. Gary Ulaner, the James and Pamela Muzzy Chair of Molecular Imaging and Therapy at the Hoag Family Cancer Institute and a Professor of Radiology and Translational Genomics at the University of Southern California, “yet many people are not even aware that ILC is a unique subtype of breast cancer with its own distinct genetic, molecular, histologic, and imaging characteristics. At 15% of all breast cancers, that is 40,000 new ILC cases a year in the United States alone. Clearly this is an underappreciated area ripe for education and research.”


Development of new radiotracer and radiopharmaceutical therapies that specifically target ILC will dramatically advance the knowledge and treatment of lobular breast cancer and potentially help
prevent delayed diagnoses of ILC and improve precision medicine for ILC.

It will put an end to the common refrain of ILC patients “I had clean mammograms for years that did not detect anything and then a biopsy found my very large lobular tumor, which had apparently been growing for years.”