Is radioactive iodine- 131 treatment related to the occurrence of non-synchronous second primary malignancy in patients with differentiated thyroid cancer?
Objective Much controversy relates to the risk of non-synchronous second primary malignancies (NSSPM) after radioactive iodine treatment (RAI-131) in differentiated thyroid cancer (DTC) patients. This study evaluated the relationship between RAI-131 and NSSPM in DTC survivors with long-term follow-up. Materials and methods Retrospective analysis of 413 DTC cases was performed; 252 received RAI-131 and 161 were treated with thyroidectomy alone. Exclusion criteria were: prior or synchronous non-thyroidal malignancies (within the first year), familial syndromes associated to multiple neoplasms, ionizing radiation exposure or second tumors with unknown histopathology. Results During a mean follow-up of 11.0 ± 7.5 years, 17 (4.1%) patients developed solid NSSPM. Patients with NSSPM were older than those without (p = 0.02). RAI-131 and I-131 cumulative activity were similar in patients with and without NSSPM (p = 0.18 and p = 0.78, respectively). Incidence of NSSPM was 5.2% in patients with RAI-131 treatment and 2.5% in those without RAI-131 (p = 0.18). Using multivariate analysis, RAI-131 was not significantly associated with NSSPM occurrence (p = 0.35); age was the only independent predictor (p = 0.04). Under log rank statistical analysis, after 10 years of follow-up, it was observed a tendency of lower NSSPM-free survival among patients that received RAI-131 treatment (0.96 vs . 0.87; p = 0.06), what was not affected by age at DTC diagnosis. Conclusion In our cohort of DTC survivors, with a long-term follow-up period, RAI-131 treatment and I-131 cumulative dose were not significantly associated with NSSPM occurrence. A tendency of premature NSSPM occurrence among patients treated with RAI-131 was observed, suggesting an anticipating oncogenic effect by interaction with other risk factors.
Main Authors: | , , , , , , |
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Format: | Digital revista |
Language: | English |
Published: |
Sociedade Brasileira de Endocrinologia e Metabologia
2016
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Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2359-39972016000100009 |
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