Cytogenetic and dosimetric effects of I-131 in patients with differentiated thyroid carcinoma: comparison between stimulation with rhTSH and thyroid hormone withdrawal treatments

Autor(es)

da Silva, Marcia Augusta ; Silva Valgode, Flavia Gomes ; Gonzalez, Julia Armiliato ; Yoriyaz, Helio ; Calil Cury Guimaraes, Maria Ines ; Carvalho Pinto Ribela, Maria Teresa ; Buchpiguel, Carlos Alberto ; Bartolini, Paolo ; Okazaki, Kayo

• Tipo de documento: Artigo Científico
• Fonte: RADIATION AND ENVIRONMENTAL BIOPHYSICS; v. 55, n. 3, p. 317-328, AUG 2016.
• Citações Web of Science: 2

Resumo

A study directed to the cytogenetic and dosimetric aspects of radionuclides of medical interest is very valuable, both for an accurate evaluation of the dose received by the patients, and consequently of the genetic damage, and for the optimization of therapeutic strategies. Cytogenetic and dosimetric effects of I-131 in lymphocytes of thyroidectomized differentiated thyroid cancer (DTC) patients were evaluated through chromosome aberration (CA) technique: Euthyroid patients submitted to recombinant human thyroid-stimulating hormone (rhTSH) therapy (group A) were compared with hypothyroid patients left without levothyroxine treatment (group B). CA analysis was carried out prior to and 24 h, 1 week, 1 month and 1 year after radioiodine administration (4995-7030 MBq) in both groups. An activity-response curve of I-131 (0.074-0.740 MBq/mL) was elaborated, comparing dicentric chromosomes in vivo and in vitro in order to estimate the absorbed dose through Monte Carlo simulations. In general, radioiodine therapy induced a higher total CA rate in hypothyroid patients as compared to euthyroid patients. The frequencies of dicentrics obtained in DTC patients 24 h after treatment were equivalent to those induced in vitro (0.2903 +/- 0.1005 MBq/mL in group A and 0.2391 +/- 0.1019 MBq/mL in group B), corresponding to absorbed doses of 0.65 +/- 0.23 Gy and 0.53 +/- 0.23 Gy, respectively. The effect on lymphocytes of internal radiation induced by I-131 therapy is minimal when based on the frequencies of CA 1 year after the treatment, maintaining a higher quality of life for DTC patients receiving rhTSH-aided therapy. (AU)

• Processo FAPESP: 10/51417-0 - Estudo dosimetrico e do efeito citogenético do 131-I em pacientes com câncer diferenciado da tireóide: comparação entre terapia de estimulação com r-hTSH e terapia de suspensão do hormônio tireoidiano
• Beneficiário: Paolo Bartolini
• Modalidade de apoio: Auxílio à Pesquisa - Regular