Malignant struma ovarii with a robust response to radioactive iodine

SUMMARY

Struma ovarii is a rare, usually benign ovarian tumour with malignancy occurring in <5% of cases. Metastases, particularly seeding to bone, are extremely rare. Presentation is variable but often features local pain and/or ascites and hyperthyroidism may occur. It is not established how to best treat and follow patients with extensive disease. Case reports of radioiodine (I131) ablative therapy following thyroidectomy have shown reduced recurrence. We describe the case of a 33-year-old woman who presented with bone pain and was diagnosed with skeletal metastases with features of follicular thyroid carcinoma. However, thyroid pathology was benign. She recalled that 5 years prior, an ovarian teratoma was excised, classified at that time as a dermoid cyst. Retrospective review of this pathology confirmed struma ovarii without obvious malignant features. The patient was found to have widespread metastases to bone and viscera and her thyroglobulin was >3000 µg/L following recombinant TSH administration prior to her first dose of I131. At 25 months following radioiodine treatment, she is in remission with an undetectable thyroglobulin and clear I131 surveillance scans. This case demonstrates an unusual presentation of malignant struma ovarii together with challenges of predicting metastatic disease, and demonstrates a successful radioiodine regimen inducing remission.

LEARNING POINTS

Malignant transformation of struma ovarii (MSO) is extremely rare and even rarer are metastatic deposits in bone and viscera. MSO can be difficult to predict by initial ovarian pathology, analogous to the difficulty in some cases of differentiating between follicular thyroid adenoma and carcinoma. No consensus exists on the management for post operative treatment of MSO; however, in this case, three doses of 6Gbq radioiodine therapy over a short time period eliminated metastases to viscera and bone. Patients should continue to have TSH suppression for ~5 years. Monitoring thyroglobulin levels can predict recurrence.

Abstract P6-01-05: Enhancement of18F-FDG uptake and glycolysis by epidermal growth factor via PI3K activation in T47D breast cancer cells

It is well known that the binding of epidermal growth factor (EGF) to EGF receptors (EGFR) stimulates proliferation of breast cancer cells via activation of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signaling pathways. There was a report that glucose consumption and lactate production were increased in MDA-MB-468 breast cancer cells following EGF exposure. However, the effect of EGF in enhancing glucose uptake and signaling pathways that are involved have not been clearly revealed. We thus investigated the role of EGF in stimulation of18F-FDG uptake in T47D breast cancer cells, and further elucidated the molecular mechanisms that are involved.

Exposure of T47D cells to 100 ng/mL EGF for 24 h caused a substantial augmentation of18F-FDG uptake to even greater extents to 310.8% ± 30.1% of control cells (P &lt; 0.001), and this effect of EGF showed dose- and time-dependency. Increased glucose uptake by EGF occurred through enhanced membrane GLUT-1 expression as well as hexokinase activity. Inhibition experiments with cycloheximide showed that the metabolic effect by EGF required new protein biosynthesis. Stimulation of glucose uptake by EGF was dependent on sufficient EGFR expression because18F-FDG uptake in MCF-7 cells weakly expressing EGFR was not affected by EGF treatment. Although EGF was also a stimulator of T47D cell proliferation (137.3 ± 7.3% of basal levels at 24 h, P &lt; 0.001), the metabolic effect occurred in a manner that clearly preceded and surpassed the proliferative effect. EGF-stimulated proliferation was significantly inhibited by the EGFR inhibitor BIBX1382, the PI3K inhibitor LY294002 and the specific MAPK inhibitor PD98059. Unlike proliferation, the ability of EGF to augment18F-FDG uptake was found to be dependent on PI3K but not on MAPK activity.

These findings yield the insight into our understanding of the role of EGF and the molecular basis that are involved in glucose metabolism of breast cancer cells.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-01-05.

Cell uptake and tissue distribution of radioiodine labelled D-luciferin: implications for luciferase based gene imaging

Optical luciferase gene imaging is emerging as a method to monitor gene expression in small animals. However, there is concern over how regional availability of exogenously administered substrate may affect photon emission. We thus synthesized [125I]iodo-D-luciferin, which demonstrated substrate characteristics for firefly luciferase, and investigated its cell uptake kinetics and in vivo biodistribution. Luminescence assays of luc gene transduced cells confirmed a linear decline in emitted light units with decreasing luciferin concentration. Both luc gene transduced and control cells demonstrated a low level of cellular uptake and rapid washout of [125I]iodo-D-luciferin, although early uptake was slightly higher for transduced cells (P < 0.005). Biodistribution in ICR mice demonstrated that early uptakes in liver, lung, myocardium and muscle were lower with intraperitoneal compared to intravenous administration. In view of the poor cell uptake, uptake levels (< 3%ID/g) suggest that substrate concentration may limit light emission rates in organs such as bone, muscle, myocardium, and particularly the brain. Thus, substrate availability should be considered as a potential limiting factor for photon emission efficiency in certain organs when attempting quantitative interpretation of optical luc gene imaging.

Use of insulin to improve [18 F]fluorodeoxyglucose labelling and retention for in vivo positron emission tomography imaging of monocyte trafficking

While 18F-FDG labelling of monocytes would allow in vivo trafficking with positron emission tomography (PET), present methods suffer from poor retention of radioactivity. We investigated the feasibility of utilizing insulin for improved [18F]fluorodeoxyglucose (18F-FDG) labelling. Separated human monocytes and lymphocytes were labelled with 18F-FDG with or without 3 h insulin pre-incubation. Insulin had no effect on lymphocyte labelling (21.4+/-0.8% vs 20.8+/-1.1% efficiency, P=NS). However, for monocytes, insulin pre-incubation led to a 169+/-9% increase in labelling efficiency (19.3+/-4.1 vs 32.5+/-1.8, P<0.05), without significant effects on cell activation or viability. Moreover, while only 57.7+/-4.8% and 40.4+/-5.6% of the 18F-FDG was retained at 1 and 3 h for controls, the retention rate increased to 91.6+/-2.1% (P=0.01) and 86.5+/-1.9% (P<0.01) after insulin pre-incubation. Improved 18F-FDG retention was accompanied by a 70.3+/-7.4% decrease in glucose-6-phosphatase activity (P=0.02). PET imaging of rats showing hepatic ischaemia-reperfusion injury demonstrated higher liver uptake for monocytes labelled after insulin treatment. Thus, insulin improves monocytic 18F-FDG uptake and retention, and may provide a feasible labelling method for PET imaging.

Employer-sponsored Medicare HMO strategies: common selection criteria

Retiree health care costs have increased at an astronomical rate for employers. In order to gain control over these costs and reduce Financial Accounting Standards FAS 106 expense and liability, many employers have turned to Medicare HMOs as a solution. The Medicare HMO arena has exploded over the last few years. With the wide diversity of Medicare HMOs in the marketplace, the prospect of selecting Medicare HMOs can be daunting. However, as more and more employers offer Medicare HMOs to retirees, some common criteria to assist in the selection process have evolved. These criteria are in the categories of sufficient access, high quality care, generous benefit levels, at affordable cost. These are by no means the only criteria employers should consider; however, they should serve as a solid foundation from which a Medicare HMO strategy can be developed.