FDG- and MET-PET Imaging Reveal Glucose and Methionine Addiction in a Primary Endometrial Cancer and Methionine Addiction only in a Para-aortic Lymph-node Metastasis in a 58-year-old Patient.

BACKGROUND/AIM: Positron emission tomography (PET) imaging with either [18F]fluorodeoxyglucose (FDG) or [11C]methionine (MET) can identify glucose addiction (Warburg effect) and methionine addiction (Hoffman effect), respectively, of cancer. Combined MET-PET and FDG-PET imaging of tumors for glucose and methionine addiction has been rare, except for the brain. The present report is a case of endometrial cancer in which a lymph-node metastasis was identified solely by MET-PET, with the primary tumor identified by both MET-PET and FDG-PET demonstrating the potential utility of MET-PET as a complementary imaging modality to FDG-PET in the detection of gynecologic malignancies.

CASE REPORT: A 58-year-old woman was diagnosed with atypical endometrial hyperplasia (AEH) based on biopsy and histopathological examination. FDG-PET revealed abnormal uptake in the endometrium, leading to a diagnosis of endometrial cancer. Subsequently, MET-PET confirmed the primary tumor and additionally detected para-aortic lymph-node metastasis, which was not visible on FDG-PET. The present findings enabled more accurate staging and suggest metabolic heterogeneity between the primary tumor and its metastasis, with the primary lesion dependent on both glucose and methionine, and the metastatic lesion methionine-dependent only.

CONCLUSION

The present case report is the first to demonstrate that lymph-node metastasis of endometrial cancer was detected exclusively using MET-PET, with no uptake observed with FDG-PET. The present findings suggest the hypothesis that metastatic lesions may undergo a metabolic shift from the primary tumor, changing from addiction to both glucose and methionine in the primary tumor, to methionine addiction alone in the metastasis.