PET Techniques Provide More Accurate Diagnosis, Prognosis in Challenging Breast Cancer Cases

In two new studies featured in the February issue of The Journal of Nuclear Medicine, researchers are revealing how molecular imaging can be used to solve mysteries about difficult cases of breast cancer. One article focuses on an imaging agent that targets estrogen receptors in estrogen receptor–positive breast cancer patients with formerly inconclusive assessments, and the second highlights a different imaging agent’s ability to help predict the prognosis for patients undergoing chemotherapy for a very aggressive type of breast cancer.

Conventional imaging and biopsy are not always enough to diagnose and characterize suspected metastatic breast cancers, especially for patients who cannot receive repeated biopsies due to the location of the cancer or other existing illnesses. It is estimated that 75 percent of breast tumors show estrogen receptor activity at the point of diagnosis, and that estrogen receptor expression is an indicator of not only active cancer lesions, but patients’ potential response to therapy, as well.

Researchers found that whole-body positron emission tomography (PET) with 16a-¹⁸F-fluoro-17b-estradiol (¹⁸F-FES), a molecular imaging technique, provides an entirely non-invasive means of capturing estrogen receptor expression in estrogen receptor–positive metastatic breast cancer. It has the potential to help physicians make more accurate judgments about extent of disease, specifically whether anti-hormonal therapies would be beneficial for patients who had inconclusive assessments using more conventional methods.

“Physicians are routinely faced with uncertainty about diagnosis or treatment decision-making,” says Geke Hospers, MD, PhD, professor of medical oncology, University Medical Center Groningen, The Netherlands. “These problems result in delays in diagnosis and institution of the right treatment, and this remains true for patients of breast cancer. The specificity of the FES-tracer for estrogen receptors makes this technique ideal for aiding physicians working with clinical dilemmas in estrogen-receptor positive breast cancer patients and could potentially lead to faster diagnoses and earlier implementation of appropriate treatments.”

In this study, 33 women with a history of estrogen-receptor positive breast cancer and a formerly inconclusive assessment were imaged with 18F-FES PET to evaluate whether the technique improved diagnosis and clinical decisions about treatment. In 88 percent of subjects, 18F-FES PET was found to improve diagnostic information, and in 48 percent, it prompted a change in treatment. This molecular imaging technique was especially helpful for detecting bone metastases.

The second article is a prospective study of patients with triple-negative breast cancer receiving chemotherapy before scheduled surgery. This type of breast cancer is an aggressive type of breast tumor that accounts for 15 percent of invasive breast cancers. In this study, researchers evaluated 18F-FDG-PET/CT, a molecular imaging method that allows physicians to gauge how metabolically active tumors are in order to gauge a patient’s predicted therapy response and prognosis after treatment. This information is valuable because very metabolically active tissues indicate active tumor growth and can signal potential failures and relapse after treatment.