RESUMO
BACKGROUND: Pulmonary metastases from papillary thyroid carcinoma shorten the survival of the hosts. Treatments with 131-I have been reported to induce disappearance of these tumors in a large proportion of afflicted patients. In this study, consecutive patients with diffuse micronodular lung metastases from papillary thyroid carcinoma were examined to determine if disappearance of tumor occurred, and how much disappeared, after substantial amounts of 131-I were administered. METHODS: Of 232 patients treated with 131-I for thyroid carcinoma between 1985 and 1994, 12 patients between the ages of 5 and 45 years exhibited evidence of micronodular metastases to the lungs that concentrated 131-I. Each patient had undergone total or nearly total thyroidectomy and cervical lymph node dissection. All neoplasms were well differentiated papillary carcinoma, but one also had focal, poorly differentiated insular components. Follicle formation by tumors varied from less than 10% to 100% of the histologic sections. Effects of treatment were measured by three indices: chest X-ray and/or CT images, scintigraphic images, and serum thyroglobulin levels. Individual activities of 131-I ranged from 2.2 gigabequerel (GBq) (initial activity in the 5-year-old patient) to 13 GBq, and were greater than 7.4 GBq in 6 patients. Only one treatment was given to three patients, two were given to seven, and more than two were given to two. The duration of follow-up was at least one year. RESULTS: In two patients, the only evidence of lung metastases was on scintigraphic images made a few days after treatment. Another patient had a normal X-ray but showed diffuse uptake of 131-I in the lungs on a diagnostic scintiscan. Of the nine patients with abnormal X-ray and CT images, seven showed improvement, but tumors disappeared in only two. In the ten patients with abnormalities on the diagnostic scintiscans, five eventually manifested no abnormality. At the outset, thyroglobulin levels exceeded 10 ng/mL in each patient; 3 individuals exhibited a decline in level by 25% or more, and a value of less than 6 ng/mL, uncomplicated by thyroglobulin antibodies, was seen in two patients. Only two patients attained normality in all three indices. Hematologic toxicity was modest and reversible. CONCLUSIONS: Despite a number of previous reports that pulmonary metastases from thyroid carcinoma disappear in approximately half of patients treated with 131-I, evidence of tumor reduction was found in most, but a complete remission occurred in only 2 of 12 patients. Nevertheless, 131-I therapy may be useful to decrease the tumor burden in many such patients.
Assuntos
Carcinoma Papilar/radioterapia , Carcinoma Papilar/secundário , Radioisótopos do Iodo/uso terapêutico , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/secundário , Neoplasias da Glândula Tireoide/patologia , Adolescente , Adulto , Carcinoma Papilar/diagnóstico por imagem , Carcinoma Papilar/patologia , Criança , Pré-Escolar , Feminino , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/patologia , Masculino , Pessoa de Meia-Idade , Cintilografia , Dosagem RadioterapêuticaRESUMO
We searched for methods that would enable prescriptions of the maximum tolerable doses of iodine-131 metaiodobenzylguanidine (MIBG) and iodine-125 MIBG in the treatment of patients with neuroblastoma. We correlated doses, defined in different ways, with subsequent platelet levels in treated patients to determine accurate predictors of the most frequent toxicity, thrombocytopenia. Nine patients with neuroblastoma were given 131I-MIBG (4.9-8.1 GBq or 132-220 mCi) and ten were given 125I-MIBG (8.3-30.0 GBq or 224-809 mCi) as initial treatments. These therapies were sufficiently varied that correlations could be made between indices of the doses and the subsequent toxicity as reflected in circulating platelet levels. Predictors of toxicity were: whole-body absorbed dose of radiation (cGy) calculated from pretherapy tracer doses of 131I-MIBG; GBq/kg of body weight; and GBq/m2 of body surface area. Toxicity was recorded as the nadir of the platelet level and platelet/pretherapeutic level (platelet ratio). For treatments with 131I-MIBG, the highest correlation was obtained between cGy and the log10-transformed platelet ratio (r = -0.86), but comparison of GBq/m2 and the platelet nadir (r = -0.76) or the platelet ratio (r = -0.74) or the log10 transformed platelet ratio (r = -0.73) gave comparable and statistically significant results. For treatments with 125I-MIBG, significant correlations were obtained between GBq/m2 and the platelet ratio (r = -0.81) or GBq/kg and the log10-transformed platelet ratio; the correlation between cGy and any toxicity index was low. Per administered GBq, 131I-MIBG was 2.6 times more potent than 125I-MIBG in causing a platelet ratio of 0.1.(ABSTRACT TRUNCATED AT 250 WORDS)