Mild Decreases in White Blood Cell and Platelet Counts Are Present One Year After Radioactive Iodine Remnant Ablation
Bone marrow suppression after multiple, high-dose radioactive iodine (RAI) therapies is well described. However, changes in the peripheral complete blood count (CBC) that may occur after a single treatment of RAI such as that commonly used for routine remnant ablation is much less well studied. In this retrospective trial, we examined the rate of persistent anemia, leukopenia, and thrombocytopenia 1 year after a single RAI administration.
Peripheral blood counts at baseline were compared to those obtained 1 year after RAI remnant ablation in 206 consecutive thyroid cancer patients. Analyses were performed to determine the potential impact of both the method of preparation (recombinant human thyroid stimulating hormone [rhTSH] vs. thyroid hormone withdrawal) and administered activity of (131)I on hemoglobin, white blood cell (WBC), and platelet counts.
Comparison of the baseline CBC before RAI ablation (median administered activity of approximately 3700 MBq or 100 mCi) with the follow-up CBC done 1 year later demonstrated a statistically significant decline in total WBC (6.7 +/- 2.1 x 10(9) vs. 6.0 +/- 1.8 x 10(9)/L, p < 0.001; 9.7% below the reference range at 1-year follow-up) and platelet (272 +/- 67 vs. 250 +/- 65 x 10(9)/L, p < 0.001; 5.8% below the reference range at 1-year follow-up) with no significant change in hemoglobin (1.40 +/- 0.14 vs. 1.40 +/- 0.14 g/L or 14.0 +/- 1.4 vs. 14.0 +/- 1.4 g/dL; 1.5% below the reference range at 1-year follow-up). There were no significant clinical complications observed during the 1-year follow-up period. The changes in total WBC and platelets were not related to the method of preparation or the administered activity of RAI.
A single RAI treatment of approximately 3700 MBq (100 mCi) after thyroidectomy is associated with a statistically significant, mild decline in WBC and platelet counts that persists for at least 1 year after ablation. Given the small magnitude of the changes and the lack of clinically significant adverse events, these observations should not decrease the use of RAI ablation in moderate to high-risk patients in whom the benefits of ablation are likely to outweigh these minor risks.
Available from: Marene IB Landström
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ABSTRACT: Anaplastic thyroid carcinoma (ATC) is one of the most malignant tumors in humans, and currently there is no effective treatment. In the present study we investigated the effect of an endogenous estrogen metabolite, 2-methoxyestradiol (2-ME), on the growth of human ATC cells. 2-ME treatment had a strong growth inhibitory effect on five human ATC cell lines (HTh7, HTh 74, HTh83, C643, and SW1736), but showed no effect on one cell line (KAT-4). Cell cycle analysis of the growth-inhibited cells showed that 2-ME induced a G(2)/M-arrest, followed by an increased fraction of cells in sub-G(1). Analysis of internucleosomal DNA laddering as well as DNA fragmentation in a terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assay demonstrated a high number of cells undergoing apoptosis after 2-ME treatment. An increased activation of caspase-3 and caspase-8 by 2-ME was observed, and inhibition of caspase-3 decreased the apoptotic effect. Addition of 2-ME increased activity of p38 mitogen-activated protein kinase (MAPK) in the sensitive HTh7 as well as the refractory KAT-4 cells, however, activation of stress-activated protein kinase/c-jun aminoterminal kinase (SAPK/JNK) was seen only in the HTh7 cells. Inhibitors of p38 MABK and SAPK/JNK significantly attenuated the 2-ME effect. Taken together, our data demonstrate an antiproliferative and apoptotic effect of 2-ME on ATC cells involving activation of MAPKs.
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ABSTRACT: Risk assessment is the cornerstone of contemporary management of thyroid cancer. Following thyroid surgery, an initial risk assessment of recurrence and disease-specific mortality is made using important intra-operative findings, histologic characteristics of the tumor, molecular profile of the tumor, post-operative serum thyroglobulin and any available cross-sectional imaging studies. This initial risk assessment is used to guide recommendations regarding the need for remnant ablation, external beam irradiation, systemic therapy, degree of TSH suppression, and follow-up disease detection strategy over the first 2 years after initial therapy. While this initial risk stratification provides valuable information, it is a static representation of the patient in the first few weeks post-operatively that does not change over time. Depending on how the patient responds to our initial therapies, the risk of recurrence and death may change significantly during follow-up. In order to account for differences in response to therapy in individual patients and to incorporate the impact of treatment on our initial risk estimates, we recommend a re-stratification of risk at the 2-year point of follow-up. This re-stratification provides an updated risk estimate that can be used to guide ongoing management recommendations including the frequency and intensity of follow-up, degree of ongoing TSH suppression, and need for additional therapies. Ongoing management recommendations must be tailored to realistic, evolving risk estimates that are actively updated during follow-up. By individualizing therapy on the basis of initial and ongoing risk assessments, we can maximize the beneficial effects of aggressive therapy in patients with thyroid cancer who are likely to benefit from it, while minimizing potential complications and side effects in low-risk patients destined to have a full healthy and productive life after minimal therapeutic intervention.
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ABSTRACT: Radioactive iodine (RAI) in the form of (131)I has been used to treat thyroid cancer since 1946. RAI is used after thyroidectomy to ablate the residual normal thyroid remnant, as adjuvant therapy, and to treat thyroid cancer metastases. Although the benefits of using RAI in low-risk patients with thyroid cancer are debated, it is frequently used in most patients with thyroid cancer and is clearly associated with acute and long-term risks and side effects. Acute risks associated with RAI therapy include nausea and vomiting, ageusia (loss of taste), salivary gland swelling, and pain. Longer-term complications include recurrent sialoadenitis associated with xerostomia, mouth pain, dental caries, pulmonary fibrosis, nasolacrimal outflow obstruction, and second primary malignancies. This article summarizes the common complications of RAI and methods to prevent and manage these complications.
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