New guidelines issued by the National Comprehensive Cancer Network (NCCN) recommend using FES PET agents, radioactive forms of estrogen, under certain circumstances for systemically staging recurrent and metastatic breast cancer.

About 181,000 people in the U.S. are estimated to have metastatic breast cancer, which has a five-year survival rate of 28%. ER (estrogen receptor) expression is one of the most common biomarkers, but can vary within the primary tumor and across different lesions, and change over time. Oncologists rely on biopsies to determine treatment, but this approach only shows the presence of the disease in the sample of the tumor excised.

ER-targeted PET imaging with 16α-18F-fluoro-17ß Fluoroestradiol (FES) shows the extent to which cancer has spread and how concentrated ER expression is at all tumor sites. This whole-body picture of ER expression provides doctors with more information for personalizing treatments and makes them better able to determine which patients will benefit most from endocrine-based therapy, including with CDK 4/6 inhibitors.
Currently, GE HealthCare’s Cerianna imaging agent, an adjunct to biopsy for detecting ER-positive lesions, is the only FDA approved FES PET radiopharmaceutical for breast cancer specifically in the U.S., having gotten the green light in May 2020 under Zionexa USA, which GE HealthCare acquired in May 2021.

"Patients will spend less time on futile therapy, experience fewer complications from their disease, and fewer costs on medicines which are ineffective," Dr. Hannah Linden, breast medical oncologist at the University of Washington and Fred Hutchinson Cancer Center in Seattle, Washington, told HCB News.

The inclusion of FES PET agents in NCCN guidelines was based on the Society of Nuclear Medicine and Molecular Imaging recently publishing Appropriate Use Criteria for guiding referring and imaging physicians in using FES PET for ER-positive diseases.

Linden says these recommendations may push the medical community to define clinical circumstances where use of FES/PET is most appropriate, increasing access to better and more treatment options for patients, but that more research, data, experience, and production sites are needed.

"This will expand the day-to-day clinical use of FES PET because physicians and payors use NCCN Guidelines to determine management strategies," she said.

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