For Problematic Breast Cancer Cases, PET Techniques Offer More Accurate Diagnosis, Prognosis

In two new studies, researchers are demonstrating how molecular imaging can be used to answer some of the difficult questions posed by challenging cases of breast cancer. One article focuses on an imaging agent that targets estrogen receptors in estrogen receptor-positive breast cancer patients with previously inconclusive assessments, and the second reveals a different imaging agent’s ability to help predict the prognosis for patients undergoing chemotherapy for a very aggressive type of breast cancer.

The results of the study were published February 2012 issue of the Journal of Nuclear Medicine. Traditional imaging and biopsy are not always sufficient to detect and characterize suspected metastatic breast cancers, particularly for patients who cannot receive repeated biopsies due to the location of the cancer or other existing illnesses. It is estimated that 75% of breast tumors show estrogen receptor activity at the point of diagnosis, and that estrogen receptor expression is an indicator of not only active tumors, but patients’ potential response to therapy, as well.

Researchers discovered that whole-body positron emission tomography (PET) with 16a-¹⁸F-fluoro-17b-estradiol (¹⁸F-FES), a molecular imaging technique, provides a noninvasive way of capturing estrogen receptor expression in estrogen receptor-positive metastatic breast cancer. It has the potential to help clinicians to make more precise conclusions about degree of disease, specifically whether antihormonal therapies would be beneficial for patients who had inconclusive assessments using more traditional methods.

“Physicians are routinely faced with uncertainty about diagnosis or treatment decision-making,” said 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 previously inconclusive evaluation were imaged with ¹⁸F-FES PET to assess whether the technique improved diagnosis and clinical decisions about treatment. In 88% of study participants, ¹⁸F-FES PET was found to improve diagnostic data, and in 48%, it prompted a change in treatment. This molecular imaging technique was particularly 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% of invasive breast cancers. In this study, researchers evaluated ¹⁸F-FDG-PET/CT, a molecular imaging modality that allows physicians to assess how metabolically active tumors are in order to assess 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.

Participants--20 patients with triple-negative breast cancer--underwent PET imaging with ¹⁸F-FDG at the outset of chemotherapy and again after the second cycle of treatment and were evaluated to determine metabolic changes in tumors during therapy. At the point of surgery, six patients showed that their therapy had been completely successful, and 14 others were found to have remaining tumors after therapy. Researchers found that patients with a less than 42% decrease in metabolism of the agent after two cycles of chemotherapy still had some residual cancer after treatment and were therefore at high risk of early relapse.

“If these findings are confirmed by other teams, interim ¹⁸F-FDG-PET/CT could become a major tool for early response assessment of this aggressive cancer, similar to the role that ¹⁸F-FDG plays in assessing aggressive lymphomas,” remarked David Groheux, MD, a lead researcher in the department of nuclear medicine at Saint-Louis Hospital (Paris, France). “Also, if these data are confirmed, patients not responding to chemotherapy prior to surgery could be switched to novel treatments that are now being investigated for this specific subtype of breast cancer, which could potentially improve the prognosis for these patients.”

This research, according to the investigators, revealed ¹⁸F-FES and ¹⁸F-FDG as two important molecular imaging agents for physicians assessing breast cancer patients with diagnostic quandaries and those with triple-negative breast cancer undergoing neoadjuvant chemotherapy. Further research would expand the use of these agents for more accurate diagnosis, tumor characterization, therapy monitoring, and prognosis for patients with aggressive, complicated, and problematic breast cancer cases. Increasingly detailed characterization, showing specific genetic or other physiologic features using molecular imaging techniques, should continue to customize additionally breast cancer imaging.

Related Links:
University Medical Center
Saint-Louis Hospital