Spotlight On | Breast Imaging
While questions about the efficacy of mammography abound—especially regarding high-risk women with dense breasts—research is turning to newer PET-based techniques for more specific diagnosis.
In the study, an 18F-FES PET exam could be requested by referring physicians for patients with a history of ER-positive breast cancer and the presence of a clinical dilemma despite complete standard work-up. All requests for 18F-FES PET required a positive arbitration by a dedicated medical oncologist and nuclear medicine physician. To validate the findings, the researchers quantified and compared 18F-FES PET lesions with centrally reviewed conventional imaging.
Kruchten et al reported that 33 patients underwent 18F-FES PET between December 2008 and October 2010. The 18F-FES uptake was highly variable between all metastases, and 45 percent of the patients with a positive 18F-FES PET finding had both 18F-FES-positive and 18F-FES-negative metastases.
Also, 18F-FES PET improved diagnostic understanding in 88 percent of the patients and led to therapy change in 48 percent of the patients.
Based on their findings, Kru-chten et al concluded that 18F-FES PET supported therapy decisions by improving diagnostic understanding and providing information on ER status of tumor lesions, except for liver metastases. Thus, they recommended that the "therapeutic consequences of having heterogeneous 18F-FES uptake and the influence of background estrogen levels should further be explored."
In the 30-month study, Groheux et al evaluated 20 consecutive patients with stage II or III breast carcinoma and a triple-negative phenotype with 18F-FDG PET/CT at baseline and after the second cycle. Neoadjuvant chemotherapy was continued irrespective of PET results. Four patients with distant metastases identified at initial staging were not included.
The researchers found that a less than 42 percent decrease in 18F-FDG uptake at two cycles means residual tumor at the end of neoadjuvant chemotherapy and a high risk of early relapse.
Thus, the authors concluded that in patients with triple-negative breast cancer, the change in 18F-FDG tumor uptake after two cycles of neoadjuvant chemotherapy "offers powerful stratification of patient outcomes. [Early on, it] identifies poor metabolic responders who would end up with residual tumor at the end of the planned neoadjuvant chemotherapy regimen and who have a high risk of early relapse."
PET imaging of estrogen receptors is diagnostic for breast cancer
With the exception of liver metastases, whole-body imaging of estrogen receptor (ER) expression with 18F-FES, an ER-specific PET tracer, can be a valuable additional diagnostic tool when standard work-up is inconclusive, particularly in breast cancer patients (J Nucl Med 2012;53(2):182-190).In the study, an 18F-FES PET exam could be requested by referring physicians for patients with a history of ER-positive breast cancer and the presence of a clinical dilemma despite complete standard work-up. All requests for 18F-FES PET required a positive arbitration by a dedicated medical oncologist and nuclear medicine physician. To validate the findings, the researchers quantified and compared 18F-FES PET lesions with centrally reviewed conventional imaging.
Kruchten et al reported that 33 patients underwent 18F-FES PET between December 2008 and October 2010. The 18F-FES uptake was highly variable between all metastases, and 45 percent of the patients with a positive 18F-FES PET finding had both 18F-FES-positive and 18F-FES-negative metastases.
Also, 18F-FES PET improved diagnostic understanding in 88 percent of the patients and led to therapy change in 48 percent of the patients.
Based on their findings, Kru-chten et al concluded that 18F-FES PET supported therapy decisions by improving diagnostic understanding and providing information on ER status of tumor lesions, except for liver metastases. Thus, they recommended that the "therapeutic consequences of having heterogeneous 18F-FES uptake and the influence of background estrogen levels should further be explored."
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PET has predictive value for triple-negative breast cancer
An interim 18F-FDG PET/CT exam after two cycles of neoadjuvant chemotherapy was predictive of pathologic response and disease-free survival in patients with triple-negative breast cancer, an aggressive subtype of breast cancer, according to a prospective study (J Nucl Med 2012;53(2):-249-254).In the 30-month study, Groheux et al evaluated 20 consecutive patients with stage II or III breast carcinoma and a triple-negative phenotype with 18F-FDG PET/CT at baseline and after the second cycle. Neoadjuvant chemotherapy was continued irrespective of PET results. Four patients with distant metastases identified at initial staging were not included.
The researchers found that a less than 42 percent decrease in 18F-FDG uptake at two cycles means residual tumor at the end of neoadjuvant chemotherapy and a high risk of early relapse.
Thus, the authors concluded that in patients with triple-negative breast cancer, the change in 18F-FDG tumor uptake after two cycles of neoadjuvant chemotherapy "offers powerful stratification of patient outcomes. [Early on, it] identifies poor metabolic responders who would end up with residual tumor at the end of the planned neoadjuvant chemotherapy regimen and who have a high risk of early relapse."