SNMMI Mars Shot: Breast Cancer

Currently, breast cancer comprises 1 in 3 new cases of cancer diagnosed in women. The Surveillance, Epidemiology, and End Results Program of the National Cancer Institute estimated that over 281,000 women would be diagnosed with—and 43,600 would die from—breast cancer in 2021, with a death rate of 19.9 per 100,000 women per year¹. Breast cancer deaths in women occur primarily when it has metastasized, or spread to other organs, such as the brain, lungs, or bones.


Many factors contribute to how breast cancer is treated and which medications are used. One factor is testing to determine whether the hormone receptors estrogen and progesterone are present in a patient’s tumors. Until recently, a biopsy of a tumor was needed to determine its hormone receptor status. A patient with metastatic breast cancer can have many tumors, and the tumors can have different hormone receptors. In that case, a treatment selected to target the biopsied tumor may not work on other tumors. By using molecular imaging to manage patients with metastatic breast cancer, physicians are able not only to find disease but also to characterize it, determine its aggressiveness, select a course of therapy, and assess the effectiveness of that therapy—sometimes after just a single cycle². Examining breast cancer with combined imaging systems, or hybrid imaging (e.g., PET/CT), enables physicians to shift from an exploratory, invasive model to one of individually adapted and guided therapies.


By investing in the research and implementation of new radiotracers such as 18F-fluoroestradiol, physicians can accurately identify estrogen-positive disease on a whole-patient level, greatly impacting patient management. More PET radiotracers are being developed to target other cancer receptors, such as human epidermal growth factor receptor 2 (HER2), found on a subset of breast malignancies. Additionally, some radiotracers may be useful in the targeted treatment of breast cancer. Radiopharmaceutical therapies are a combination of a receptor-targeting molecule and a dose of radiation that can bind to a tumor and act as a smart-bomb to target the cancer cells but not normal tissues—precision medicine.


Each new radiotracer and radiopharmaceutical therapy developed and integrated into nuclear medicine practice will improve doctors’ ability to give the right therapy to the right patient at the right time. Harnessing the power and precision of molecular imaging and therapy has the potential to increase quality of life. Nuclear medicine offers less invasive, more specific, and adaptable treatments to create better overall outcomes.