JNM: Combined tracers aid PET imaging for endometrial carcinoma

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A PET scan with F-18-fluoroestradiol (F-18-FES) may provide physicians with more information about endometrial carcinoma, according to research published in this month’s Journal of Nuclear Medicine.

"The method of PET imaging we used in the study is noninvasive, and it has tremendous potential to save women with endometrial carcinoma from undergoing unnecessary operations and biopsies that could sabotage their reproductive potential," said study author Hidehiko Okazawa, MD, PhD, professor in the division of medical imaging at the biomedical imaging research center at the University of Fukui in Fukui, Japan.

If the disease is caught early enough, the five-year survival rate is higher than 90 percent for patients with endometrial carcinoma.

A total of 22 patients with endometrial adenocarcinoma and nine with endometrial hyperplasia (mean age, 56 years) underwent F18-FES PET for estrogen receptor imaging and F18-FDG PET.

All patients underwent preoperative PET scans with F18-FES—a tracer that has been successfully used in diagnosing breast cancer—and F18-FDG to compare differences in tracer accumulation.

Although the standardized uptake value (SUV) for F18-FDG was significantly lower in endometrial hyperplasia than in carcinoma, Okazawa and colleagues found a significant difference between high-risk and low-risk carcinoma was observed only in SUV for F18-FES. Also, high-risk carcinoma showed a significantly greater F18-FDG to F18-FES ratio (3.6) than did low-risk carcinoma (1.3) and hyperplasia (0.3).

The researchers confirmed that endometrial carcinoma reduces estrogen dependency with accelerated glucose metabolism as it progresses to a higher stage or grade. By combining the two tracers, researchers were able to use a new index of uptake ratio that can better predict pathologic stages and aggressiveness of tumors.

For endometrial cancer, estrogen receptor expression is related to endocrine responsiveness and indicated by FES uptake. Poorly differentiated tumors often have increased and abnormal breakdown of glucose, indicated by FDG.

According to the authors, the results of the study were encouraging, with the combined techniques having 86 percent accuracy.

The researchers concluded that the combination of the two tracers, as indicated by the study, was better than either alone at indicating the aggressiveness of the tumor.