da Silva Márcia Augusta, Valgôde Flávia Gomes Silva, Gonzalez Júlia Armiliato, Yoriyaz Hélio, Guimarães Maria Inês Calil Cury, Ribela Maria Teresa Carvalho Pinto, Buchpiguel Carlos Alberto, Bartolini Paolo, Okazaki Kayo
Centro de Biotecnologia, Instituto de Pesquisas Energéticas e Nucleares (IPEN), Comissão Nacional de Energia Nuclear (CNEN), IPEN-CNEN/SP, Caixa Postal 11049, Av. Prof. Lineu Prestes, 2242, Cidade Universitária, São Paulo, CEP 05508-900, Brazil.
Centro de Medicina Nuclear, Faculdade de Medicina da Universidade de São Paulo, Rua Ouvídio Pires de Campos, s/n, São Paulo, Brazil.
Radiat Environ Biophys. 2016 Aug;55(3):317-28. doi: 10.1007/s00411-016-0646-5. Epub 2016 Mar 24.
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 (131)I 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 (131)I (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 (131)I 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.
一项针对具有医学意义的放射性核素的细胞遗传学和剂量学方面的研究非常有价值，这对于准确评估患者所接受的剂量以及由此产生的遗传损伤，进而优化治疗策略都很重要。通过染色体畸变（CA）技术评估了甲状腺切除术后分化型甲状腺癌（DTC）患者淋巴细胞中（131）I的细胞遗传学和剂量学效应：将接受重组人促甲状腺激素（rhTSH）治疗的甲状腺功能正常患者（A组）与未接受左甲状腺素治疗的甲状腺功能减退患者（B组）进行比较。在两组患者给予放射性碘（4995 - 7030MBq）之前以及给药后24小时、1周、1个月和1年进行CA分析。绘制了（131）I（0.074 - 0.740MBq/mL）的活性-反应曲线，比较体内和体外的双着丝粒染色体，以便通过蒙特卡罗模拟估算吸收剂量。总体而言，与甲状腺功能正常的患者相比，放射性碘治疗在甲状腺功能减退患者中诱导的总CA率更高。治疗后24小时在DTC患者中获得的双着丝粒频率与体外诱导的频率相当（A组为0.2903±0.1005MBq/mL，B组为0.2391±0.1019MBq/mL），分别对应于0.65±0.23Gy和0.53±0.23Gy的吸收剂量。基于治疗后1年CA的频率，（131）I治疗引起的内照射对淋巴细胞的影响最小，接受rhTSH辅助治疗的DTC患者保持了较高的生活质量。
