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Barcelos RN, Camacho CP, da Conceição de O C Mamone M, Ikejiri ES, Vanderlei FAB, Yang JH, Padovani RP, Martins LAL, Biscolla RPM, Macellaro D, Lindsey SC, Maciel RMB, Martins JRM. Risk of malignancy and diagnostic accuracy of fine-needle aspiration biopsy in thyroid nodules with diameters greater than 4 centimeters. Arch Endocrinol Metab 2023; 67:e000644. [PMID: 37364146 PMCID: PMC10661008 DOI: 10.20945/2359-3997000000644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/04/2023] [Indexed: 06/28/2023]
Abstract
Objective The risk of malignancy and diagnostic accuracy of fine-needle aspiration biopsy (FNAB) of thyroid nodules (TN) with diameters ≥ 3-4 cm remains controversial. However, some groups have indicated surgical treatment in these patients regardless of the FNAB results. We aimed to evaluate the diagnostic accuracy of the FNAB in systematically resected ≥4 cm TN and if the risk of malignancy is higher in these patients. Subjects and methods We retrospectively evaluated 138 patients (142 nodules) with TN with diameters ≥4 cm who underwent thyroidectomy. Results The FNAB results were nondiagnostic/unsatisfactory (ND/UNS) in 2.1% of the cases and benign in 51.4%. They indicated atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) in 23.9% of cases, follicular neoplasia/suspicious for a follicular neoplasm (FN/SFN) in 9.2%, suspicion of malignancy (SUS) in 8.5%, and malignant in 4.9%. The histopathological analysis after thyroidectomy revealed a thyroid cancer rate of 100% in the FNABs classified as malignant, 33.3% in SUS cases, 7.7% in FN/SFN, 17.6% in AUS/FLUS, and 4.1% in benign FNABs. None of the ND/UNS FNABs were malignant. The global malignancy diagnosis was 14.8% (n = 21). However, the rate of false negatives for FNAB was low (4.1%). Conclusion We showed that the risk of malignancy in nodules with diameters ≥4 cm was higher compared to the risk of thyroid cancer in TN in general. However, we found a low rate of false-negative cytological results; therefore, our data do not justify the orientation of routine resection for these larger nodules.
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Affiliation(s)
- Rafaela N Barcelos
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Cléber P Camacho
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
- Laboratório de Inovação Molecular e Biotecnologia, Programa de Pós-graduação em Medicina, Universidade Nove de Julho (Uninove), São Paulo, SP, Brasil
| | - Maria da Conceição de O C Mamone
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Elza S Ikejiri
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Felipe A B Vanderlei
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Ji H Yang
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Rosália P Padovani
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Leandro A L Martins
- Laboratório de Anatomia Clínica e Patológica, Hospital Israelita Albert Einstein, São Paulo, SP, Brasil
| | - Rosa Paula M Biscolla
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Danielle Macellaro
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Susan C Lindsey
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Rui M B Maciel
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - João Roberto M Martins
- Centro de Doenças da Tireoide e Laboratório de Endocrinologia Molecular e Translacional, Disciplina de Endocrinologia e Metabologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil,
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Couto JS, Almeida MFO, Trindade VCG, Marone MMS, Scalissi NM, Cury AN, Ferraz C, Padovani RP. A cutoff thyroglobulin value suggestive of distant metastases in differentiated thyroid cancer patients. Braz J Med Biol Res 2020; 53:e9781. [PMID: 33053096 PMCID: PMC7561073 DOI: 10.1590/1414-431x20209781] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 07/15/2020] [Indexed: 11/22/2022] Open
Abstract
Serum thyroglobulin is used as part of the early postoperative assessment of differentiated thyroid cancer (DTC) since there is a clear relationship between an increased risk of recurrence and persistent disease after initial treatment and high postoperative stimulated thyroglobulin (ps-Tg) values. Thus, although ps-Tg above 10-30 ng/mL is considered an independent predictor of worse prognosis, the value that is associated with distant metastases is not defined. Thus, this was our objective. We selected 655 DTC patients from a nuclear medicine department database (Irmandade Santa Casa de Misericórdia de São Paulo, Brazil). All patients had received total thyroidectomy and radioactive iodine (RAI) therapy and had ps-Tg values higher than 10 ng/mL with negative anti-thyroglobulin antibodies. Then, we selected patients who presented post-therapy whole-body scan with pulmonary and/or bone uptake but with no mediastinum or cervical uptake. Patients with negative findings on functional imaging or any doubt on lung/bone uptake were submitted to additional exams to exclude another non-thyroid tumor. Of the 655 patients, 14.3% had pulmonary and 4.4% bone metastases. There was a significant difference in ps-Tg levels between patients with and without metastases (P<0.001). The cutoff value of ps-Tg was 117.5 ng/mL (sensitivity: 70.2%; specificity: 71.7%) for those with lung metastasis, and 150.5 ng/mL (sensitivity: 79.3%; specificity: 85%) for those with bone metastasis. The cutoff value for patients with eitherpulmonary or bone metastasis was 117.5 ng/mL (sensitivity: 70.2%; specificity: 83.7%). Our findings demonstrated that ps-Tg could predict distant metastasis in DTC patients. We identified a cutoff of 117.5 ng/mL with a high negative predictive value of 93.7%.
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Affiliation(s)
- J S Couto
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil
| | - M F O Almeida
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil
| | - V C G Trindade
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil
| | - M M S Marone
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.,Serviço de Medicina Nuclear, Nuclimagem, São Paulo, SP, Brasil.,Faculdade de Ciências Médicas da Santa Casa de São Paulo, São Paulo, SP, Brasil
| | - N M Scalissi
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.,Faculdade de Ciências Médicas da Santa Casa de São Paulo, São Paulo, SP, Brasil
| | - A N Cury
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.,Faculdade de Ciências Médicas da Santa Casa de São Paulo, São Paulo, SP, Brasil
| | - C Ferraz
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.,Faculdade de Ciências Médicas da Santa Casa de São Paulo, São Paulo, SP, Brasil
| | - R P Padovani
- Serviço de Endocrinologia e Metabologia, Departamento de Medicina, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.,Serviço de Medicina Nuclear, Nuclimagem, São Paulo, SP, Brasil.,Faculdade de Ciências Médicas da Santa Casa de São Paulo, São Paulo, SP, Brasil
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Santarosa VA, Orlandi DM, Fiorin LB, Kasamatsu TS, Furuzawa GK, Kunii IS, Padovani RP, Marone MMS, Castiglioni ML, Vieira JGH, Maciel RMB, Dias-da-Silva MR, Martins JRM. Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves’ disease. Arch Endocrinol Metab 2015; 59:501-6. [DOI: 10.1590/2359-3997000000082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/18/2015] [Indexed: 11/22/2022]
Affiliation(s)
| | | | | | | | | | | | - Rosália P. Padovani
- Universidade Federal de São Paulo, Brasil; Irmandade Santa Casa de Misericórdia de São Paulo, Brasil
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Padovani RP, Maciel RM, Kasamatsu TS, Freitas BC, Marone MM, Camacho CP, Biscolla RPM. Assessment of the Effect of Two Distinct Restricted Iodine Diet Durations on Urinary Iodine Levels (Collected over 24 h or as a Single-Spot Urinary Sample) and Na(+)/I(-) Symporter Expression. Eur Thyroid J 2015; 4:99-105. [PMID: 26279995 PMCID: PMC4521067 DOI: 10.1159/000433426] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 05/18/2015] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION A restricted iodine diet (RID) may be recommended for depletion of the whole-body iodine pool in patients with differentiated thyroid cancer referred for radioiodine treatment or a whole-body scan. Evaluation of the iodine pool is possible through urinary iodide (UI) measurements, which can be collected in 24-hour (24U) or spot urinary (sU) samples. However, the minimum period required for an RID to lower the iodine pool, the measurement of iodine in sU samples as a iodine pool marker, and the influence of the iodine pool on Na(+)/I(-) symporter (NIS) expression are debatable in the literature. OBJECTIVES To compare the effects of 15- and 30-day RID on UI measurements in 24U and sU samples and the impact of RID on NIS expression. METHODS Thyroidectomized patients went on a 15- or 30-day RID and collected 24U and sU samples before and after the RID. Twenty healthy individuals were evaluated for mRNA NIS expression before and after the RID. RESULTS Of 306 patients, only 125 properly complied with both the RID and 24U collection. We observed a correlation between sU and 24U UI before the RID (n = 306, ρ = 0.47, p < 0.001), after a 15-day RID (n = 79, ρ = 0.49, p < 0.001), and after a 30-day RID (n = 46, ρ = 0.73, p < 0.001). There was a significant decrease in UI after the RID. The median UI measurement was 275 μg/l at baseline and 99 and 80 μg/l after a 15- and 30-day RID, respectively. There was a significant increase in NIS expression after a 15-day RID. CONCLUSIONS A 15-day RID is sufficient to deplete the iodine pool. sU can replace 24U UI as a marker for assessing the iodine pool. NIS expression was increased after a 15-day RID.
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Affiliation(s)
- Rosália P. Padovani
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
- Department of Nuclear Medicine, Irmandade Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil
| | - Rui M.B. Maciel
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
- *Prof. Rui M.B. Maciel, MD, PhD, Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Pedro de Toledo 669, 11th floor, São Paulo, SP 04039-033 (Brazil), E-Mail
| | - Teresa S. Kasamatsu
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
| | - Beatriz C.G. Freitas
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
| | - Marilia M.S. Marone
- Department of Nuclear Medicine, Irmandade Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil
| | - Cleber P. Camacho
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - Rosa Paula M. Biscolla
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
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Padovani RP, Kasamatsu TS, Nakabashi CC, Camacho CP, Andreoni DM, Malouf EZ, Marone MM, Maciel RM, Biscolla RPM. One month is sufficient for urinary iodine to return to its baseline value after the use of water-soluble iodinated contrast agents in post-thyroidectomy patients requiring radioiodine therapy. Thyroid 2012; 22:926-30. [PMID: 22827435 PMCID: PMC3429278 DOI: 10.1089/thy.2012.0099] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND There is a concern regarding the use of iodinated contrast agents (ICA) for chest and neck computed tomography (CT) to localize metastatases in patients with differentiated thyroid cancer (DTC). This is because the iodine in ICA can compete with (131)I and interfere with subsequent whole scans or radioactive iodine treatment. The required period for patients to eliminate the excess iodine is not clear. Therefore, knowing the period for iodine levels to return to baseline after the injection of ICA would permit a more reliable indication of CT for DTC patients. The most widely used marker to assess the plasmatic iodine pool is the urinary iodine (UI) concentration, which can be collected over a period of 24 hours (24U) or as a single-spot urinary sample (sU). As 24U collections are more difficult to perform, sU samples are preferable. It has not been established, however, if the measurement of iodine in sU is accurate for situations of excess iodine. METHODS We evaluated 25 patients with DTC who received ICA to perform chest or neck CT. They collected 24U and sU urinary samples before the CT scan and 1 week and 1, 2, and 3 months after the test. UI was quantified by a semiautomated colorimetric method. RESULTS Baseline median UI levels were 21.8 μg/dL for 24U and 26 μg/dL for sU. One week after ICA, UI median levels were very high for all patients, 800 μg/dL. One month after ICA, however, UI median levels returned to baseline in all patients, 19.0 μg/dL for 24U and 20 μg/dL for sU. Although the values of median UI obtained from sU and 24U samples were signicantly different, we observed a significant correlation between samples collected in 24U and sU in all evaluated periods. CONCLUSION One month is required for UI to return to its baseline value after the use of ICA and for patients (after total thyroidectomy and radioiodine therapy) to eliminate the excess of iodine. In addition, sU samples, although not statistically similar to 24U values, can be used as a good marker to evaluate patients suspected of contamination with iodine.
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Affiliation(s)
- Rosália P. Padovani
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
- Department of Nuclear Medicine, Irmandade Santa Case de Misericórdia de São Paulo, São Paulo, Brazil
| | - Teresa S. Kasamatsu
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Claudia C.D. Nakabashi
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - Cleber P. Camacho
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - Danielle M. Andreoni
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - Eduardo Z. Malouf
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - Marilia M.S. Marone
- Department of Nuclear Medicine, Irmandade Santa Case de Misericórdia de São Paulo, São Paulo, Brazil
| | - Rui M.B. Maciel
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - Rosa Paula M. Biscolla
- Thyroid Diseases Center and Laboratory of Molecular and Translational Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- Thyroid Diseases Center, Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
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Padovani RP, Robenshtok E, Brokhin M, Tuttle RM. Even without additional therapy, serum thyroglobulin concentrations often decline for years after total thyroidectomy and radioactive remnant ablation in patients with differentiated thyroid cancer. Thyroid 2012; 22:778-83. [PMID: 22780333 DOI: 10.1089/thy.2011.0522] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Current management guidelines suggest that 6-12 months after total thyroidectomy and radioactive iodine remnant ablation (RAI-RA), patients with differentiated thyroid cancer should be re-evaluated with serum thyroglobulin (Tg) and neck ultrasonography to assess the efficacy of initial treatment and to guide subsequent management. However, if serum Tg levels can continue to decline for many years after RAI-RA, then an early assessment of response to therapy could lead to excessive evaluations and treatments in patients with low-level Tg values that are likely to resolve over time without additional therapies. METHODS Serum Tg concentrations in patients with differentiated thyroid cancer, who had been thyroidectomized (Tx), received RAI-RA, and who were receiving levothyroxine to suppress serum thyrotropin (suppressed serum Tg), were retrospectively analyzed. The study included 299 patients, 69% of whom were women with an overall median age of 46 years and who had a median follow-up of 7 years. The study was limited to patients who received no additional treatments beyond total Tx, RAI-RA, and levothyroxine therapy to suppress thyrotropin. The primary endpoints were the time required to achieve the lowest Tg (nadir Tg) and the time required to achieve a suppressed serum Tg<1 ng/mL. RESULTS The nadir -suppressed serum Tg was achieved by 6 months in 58% of the patients and by 12 months in 75% of the patients. The remaining 25% of patients required 18 months or longer to reach the nadir Tg. However, in the subgroup of patients that eventually reached a nadir suppressed serum Tg<1 ng/mL (n=223 patients), this goal was achieved by 6 months in 81%, by no more than 12 months in 91%, and by no more than 18 months in 94%. In patients with a 6-month suppressed serum Tg of 1-5 ng/mL, 54% eventually developed a suppressed serum Tg of <1 ng/mL without additional therapy. CONCLUSIONS In patients selected for continued observation, serum Tg levels often continue to decline for several years after total Tx and RAI-RA. While a 6-12-month assessment of the response to initial therapy is useful in patient management, strong consideration should be given to continued observation without additional therapy in patients with well-differentiated thyroid cancer who have 6-month suppressed serum Tg values of 1-5 ng/mL without a structurally identifiable disease.
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Affiliation(s)
- Rosália P Padovani
- Endocrinology Service, Federal University of Sao Paulo, Sao Paulo, Brazil
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