Treatment of advanced differentiated thyroid carcinoma with high activity radioiodine therapy

SPECT/CT-based dosimetry of salivary glands and iodine-avid lesions following 131I therapy

Objective

The purpose was to provide uptake and radiation dose estimates to salivary glands (SG) and pathologic lesions following radioiodine therapy (RIT) of differentiated thyroid cancer patients (DTC).

Methods

A group of DTC patients (n = 25) undergoing ¹³¹I therapy joined this study with varying amounts of therapeutic activity. Sequential SPECT/CT scans were acquired at 4 ± 2, 24 ± 2, and 168 ± 3 h following administration of 3497-9250 MBq 131I. An earlier experiment with Acrylic glass body phantom (PET Phantom NEMA 2012 / IEC 2008) was conducted for system calibration including scatter, partial volume effect and count loss correction. Dose calculation was made via IDAC-Dose 2.1 code.

Results

The absorbed dose to parotid glands was 0.04-0.97 Gy/GBq (median: 0.26 Gy/GBq). The median absorbed dose to submandibular glands was 0.14 Gy/GBq (0.05 to 0.56 Gy/GBq). The absorbed dose to thyroid residues was from 0.55 to 399.5 Gy/GBq (median: 21.8 Gy/GBq), and that to distal lesions ranged from 0.78 to 28.0 Gy/GBq (median: 3.12 Gy/GBq). 41% of the thyroid residues received dose > 80 Gy, 18% between 70-80 Gy, 18% between 40-70 Gy, and 23% has dose < 40 Gy. In contrast, 18% of the metastases exhibited a dose > 80 Gy, 9% between 40-60 Gy, and the dose to the vast majority of lesions (64%) was < 40 Gy.

Conclusion

It was inferred that dose estimation after RIT with SPECT/CT is feasible to apply, together with good agreement with published ¹²⁴I PET/CT dose estimates. A broad and sub-effective dose range was estimated for thyroid residues and distal lesions. Moreover, the current methodology might be useful for establishing a dose-effect relationship and radiation-induced salivary glands damage after RIT.

Hybrid Vision-Fusion system for whole-body scintigraphy

Radioiodine therapy in the treatment of differentiated thyroid carcinoma (DTC) is used in clinical practice for the ablation of thyroid residues and/or destruction of tumour tissue. Whole-body scintigraphy for visualization of the spatial 131I distribution performed by a gamma camera (GC) is a standard procedure in DTC patients after application of radioiodine therapy. A common problem is the precise topographic localization of regions where radioiodine is accumulated even in SPECT imaging. SPECT/CT can provide precise topographic localization of regions where radioiodine is accumulated, but it is often unavailable, especially in developing countries because of the high price of the equipment. In this paper, we present a Vision-Fusion system as an affordable solution for 1) acquiring an optical whole-body image during routine whole-body scintigraphy and 2) fusing gamma and optical images (also available for the auto-contour mode of GC). The estimated prediction error for image registration is 1.84 mm. The validity of fusing was tested by performing simultaneous optical and scintigraphy image acquisition of the bar phantom. The fusion result shows that the fusing process has a slight influence and is lower than the spatial resolution of GC (mean value ± standard deviation: 1.24 ± 0.22 mm). The Vision-Fusion system was used for radioiodine post-therapeutic treatment, and 17 patients were followed (11 women and 6 men, with an average age of 48.18 ± 13.27 years). Visual inspection showed no misregistration. Based on our first clinical experience, we noticed that the Vision-Fusion system could be very useful for improving the diagnostic possibility of whole-body scintigraphy after radioiodine therapy. Additionally, the proposed Vision-Fusion software can be used as an upgrade for any GC to improve localizations of thyroid/tumour tissue.

Thyroid cancer: molecular aspects and new therapeutic strategies

Despite that thyroid cancer accounts for over 90% of tumors that arise from the endocrine system, these tumors barely represent 2% of solid tumors in adults. Many entities are grouped under the general term of thyroid cancer, and they differ in histological features as well as molecular and clinical behavior. Thus, the prognosis for patients with thyroid cancer ranges from a survival rate of >97% at 5 years, in the case of differentiated thyroid tumors sensitive to radioactive iodine, to a 4-month median survival for anaplastic tumors. The high vascularity in these tumors and the important role that oncogenic mutations may have in the RAS/RAF/MEK pathway and oncogenicity (as suggested by activating mutations and rearrangements of the RET gene) have led to the development of multitarget inhibitors in different histological subgroups of patients. The correct molecular characterization of patients with thyroid cancer is thought to be a key aspect for the future clinical management of these patients.

Unexpected effect of furosemide on radioiodine urinary excretion in patients with differentiated thyroid carcinomas treated with iodine 131

BACKGROUND

In patients receiving (131)I for therapeutic purposes, diuretics are frequently used in an attempt to accelerate elimination of unbound radioiodine, reduce its adverse effects, and shorten the hospital stay. The aims of our study were to investigate the influence of furosemide therapy on urinary excretion of (131)I in patients with differentiated thyroid cancer (DTC), referred to radioiodine ablation after thyroidectomy, and to investigate whether diuretics are useful in daily practice in patients with DTC.

METHODS

Forty-three patients with DTC who had normal renal function and low (131)I uptake in cervical region (3.55 +/- 3.45%) were included in this study. The furosemide (20 mg) and potassium chloride (250 mg) were given orally to 23 patients 3 hours after the (131)I administration, and then q8h for 3 days. Twenty patients did not receive either furosemide or potassium chloride. After (131)I administration, the patients collected their urine for 3 days, and radioactivity of urine sample from each micturition was expressed as percentage of the administered dose. Radioactivity of blood samples was measured after 72 hours, and the values were corrected for decay of (131)I and expressed in relation to the administered dose. Initial whole-body measurement (immediately after (131)I administration) and the whole-body measurement after 72 hours were recorded for all patients. The 72-hour whole-body measurement was corrected for decay of (131)I, and expressed as a percentage of the initial whole-body measurement.

RESULTS

Urinary excretion of (131)I was significantly lower in the patients who were taking furosemide and potassium chloride compared with the control group. The whole-body measurements after 72 hours (13.22 +/- 6.55% vs. 8.24 +/- 3.39% of the initial; p < 0.01, respectively) and the blood radioactivity (34.66 +/- 24.84 vs. 11.64 +/- 8.32 cpm/mL per 1 MBq of administered (131)I, p < 0.01) were found to be unexpectedly higher in the patients who were taking furosemide and potassium chloride compared with the control group.

CONCLUSION

Our results demonstrated that furosemide given as an adjuvant medication in patients with DTC causes a significant decrease in urinary excretion of radioiodine and its higher blood concentration. Therefore, furosemide should not be recommended as an adjuvant therapy to radioiodine ablation in patients with DTC previously iodine depleted by low-iodine diet.

Targeting of cancer energy metabolism

The main purpose of this review is to update and analyze the effect of several antineoplastic drugs (adriamycin, apoptodilin, casiopeinas, cisplatin, clotrimazole, cyclophosphamide, ditercalinium, NSAIDs, tamoxifen, taxol, 6-mercaptopurine, and alpha-tocopheryl succinate) and energy metabolism inhibitors (2-DOG, gossypol, delocalized lipophilic cations, and uncouplers) on tumor development and progression. The possibility that these antineoplastic drugs currently used in in vitro cancer models, in chemo-therapy, or under study in phase I to III clinical trials induce tumor cellular death by altering also metabolite concentration (i.e., ATP), enzyme activities, and/or energy metabolism fluxes is assessed. It is proposed that the use of energy metabolic therapy, as an alternative or complementary strategy, might be a promising novel approach in the treatment of cancer.

The bioenergetics of cancer: is glycolysis the main ATP supplier in all tumor cells?

The molecular mechanisms by which tumor cells achieve an enhanced glycolytic flux and, presumably, a decreased oxidative phosphorylation are analyzed. As the O(2) concentration in hypoxic regions of tumors seems not limiting for oxidative phosphorylation, the role of this mitochondrial pathway in the ATP supply is re-evaluated. Drugs that inhibit glycoysis and oxidative phosphorylation are analyzed for their specificity toward tumor cells and effect on proliferation. The energy metabolism mechanisms involved in the use of positron emission tomography are revised and updated. It is proposed that energy metabolism may be an alternative therapeutic target for both hypoxic (glycolytic) and oxidative tumors. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.

Outcome after high-dose radioiodine therapy for advanced differentiated thyroid carcinoma in childhood

OBJECTIVE

To evaluate the clinical outcome in childhood patients receiving postoperative high-dose radioiodine therapy for advanced differentiated thyroid carcinoma.

METHOD

Patients under 18 years old with neck diseases (n = 4) or distant metastases (n = 10) received postoperative radioiodine ablation and repeated treatments for a median of 2 (0.8 10) years with an averaged activity of 25.0 (7.0 72.2) GBq.

RESULTS

Partial remission was achieved in 6, stable disease in 6 and progressive disease in 2 patients, without severe side effects except for two Grade 1 and one Grade 2 WHO haematological toxicity. The median survival time from diagnosis to the last treatment sessions was 5.3 (range, 0.7 14.5) years.

CONCLUSION

High-dose radioiodine treatment was well tolerated with satisfactory outcome in childhood patients with advanced differentiated thyroid carcinoma.

Energy metabolism in tumor cells

In early studies on energy metabolism of tumor cells, it was proposed that the enhanced glycolysis was induced by a decreased oxidative phosphorylation. Since then it has been indiscriminately applied to all types of tumor cells that the ATP supply is mainly or only provided by glycolysis, without an appropriate experimental evaluation. In this review, the different genetic and biochemical mechanisms by which tumor cells achieve an enhanced glycolytic flux are analyzed. Furthermore, the proposed mechanisms that arguably lead to a decreased oxidative phosphorylation in tumor cells are discussed. As the O(2) concentration in hypoxic regions of tumors seems not to be limiting for the functioning of oxidative phosphorylation, this pathway is re-evaluated regarding oxidizable substrate utilization and its contribution to ATP supply versus glycolysis. In the tumor cell lines where the oxidative metabolism prevails over the glycolytic metabolism for ATP supply, the flux control distribution of both pathways is described. The effect of glycolytic and mitochondrial drugs on tumor energy metabolism and cellular proliferation is described and discussed. Similarly, the energy metabolic changes associated with inherent and acquired resistance to radiotherapy and chemotherapy of tumor cells, and those determined by positron emission tomography, are revised. It is proposed that energy metabolism may be an alternative therapeutic target for both hypoxic (glycolytic) and oxidative tumors.

Cell death induced by 131I in a differentiated thyroid carcinoma cell line in vitro: Necrosis or apoptosis?

AIM

The apoptotic and necrotic dose-response of thyroid carcinoma cells following irradiation with I was evaluated.

METHODS

In our in-vitro model, cells of well-differentiated papillary thyroid carcinoma (B-CPAP) were incubated with increasing activity concentrations of I for 2 days. Changes in cell viability and the extents of necrosis and apoptosis were evaluated both immediately and 2 days after irradiation.

RESULTS

Viability of B-CPAP cells diminished with increasing I activity concentration. No apoptosis was detectable immediately after irradiation. Two days after irradiation significant apoptosis was found. The lowest I activity concentration at which apoptosis was detectable corresponds to about 1 MBq . ml. At higher activity concentrations a larger percentage of cells became apoptotic but the proportion decreased again at activity concentrations >10 MBq . ml. Likewise, necrosis was minimal at low activity concentrations and showed an exponential increase with rising I activity concentrations (>5-10 MBq . ml). Necrosis was already detectable immediately after irradiation and was the predominant form of cell death at high activity concentrations.

CONCLUSION

The data suggest that the nature of the cytotoxic effect of I and whether it leads to apoptotic or necrotic cell death is dose-dependent. High I doses seem to produce mainly necrotic phenomena, whereas at low I activity concentrations apoptotic phenomena prevail. The predominance of delayed apoptosis could explain why radioiodine therapy at lower doses is often linked to delayed onset and possible continuation of thyroid volume reduction over some months and even up to a year.

Pancytopenia in untreated patients with Graves' disease

Severe pancytopenia is a rare but severe complication of thyrotoxicosis. In this report, we describe four patients with Graves' disease who presented with pancytopenia at diagnosis. Methimazole (30-40 mg/d) or propylthiouracil (400 mg/d) restored normal hematopoiesis in three of the patients. The remaining patient evolved to aplastic anemia under therapy with methimazole (60 mg/d), but had an increased peripheral blood count that almost reached normal values after radioiodinetherapy and standard immunosuppressive treatment with antithymocyte globulin (700 mg/d, intravenous infusion for 5 days), oral cyclosporin (400 mg/d), prednisone (30-60 mg/d), and granulocyte colony-stimulating factor (150 microg subcutaneous injection, 3 times per week). We conclude that: (1) a hematologic evaluation of all patients with Graves' disease should be performed before administering antithyroid drugs, (2) antithyroid drugs may be administered to patients with pancytopenia and bone marrow hypercellularity but a reevaluation of the bone marrow must be done if there is no recovery of the peripheral blood cell count when euthyroidism state is achieved, (3) standard immunosuppressive treatment of aplastic anemia caused by antithyroid drugs restores normal hematopoiesis, and (4) a thyroid evaluation of patients with pancytopenia should be done, even though no related symptoms are found.