Clinical manifestations and diagnosis of distant metastases of differentiated thyroid carcinoma after initial therapy

Avaliamos 58 pacientes com metástases distantes de carcinoma de tireóide diagnosticadas após a terapia inicial. Metástases linfonodais na apresentação inicial foram verificadas em 65%. Todas as metástases linfonodais, 90% das pulmonares e apenas 25% das metástases ósseas eram assintomáticas. Radiografia revelou metástases líticas em todos os casos com acometimento ósseo; foi normal em 39,6%, mostrou micrometástases em 34,5% e macrometástases em 25,8% nos pacientes com doença pulmonar. A tireoglobulina (Tg) em uso de tiroxina foi detectável (> 1ng/ml) em todos sem anticorpos anti-tireoglobulina (TgAb), > 5ng/ml em 90% e > 10ng/ml em 80% e, após a suspensão da terapia, > 5ng/ml em 100% e > 10ng/ml em 94%. Nos pacientes com TgAb (13,8%), Tg foi indetectável em metade. Varredura diagnóstica com 5mCi de iodo 131 foi positiva em 83% e 77,6% dos pacientes com metástases ósseas e pulmonares, respectivamente e após dose ablativa, a sensibilidade foi de 100 e 93%. Dos pacientes com varredura diagnóstica negativa, 85% tinham metástases pulmonares visíveis na radiografia. Concluímos que a Tg é o método mais sensível, seguro e de menor custo no seguimento de câncer diferenciado de tireóide, e reforçamos a administração direta de uma dose ablativa de radioiodo com realização de varredura pós-dose quando a Tg estiver elevada.We studied 58 patients with distant metastases of differentiated thyroid carcinoma diagnosed after initial therapy. Lymph node metastases were observed in 65% of the patients on initial presentation. All lymph node metastases, ninety percent of the lung metastases and only 25% of the bone metastases were asymptomatic. Radiography revealed lytic metastases in cases of bone involvement, was normal in 39.6% of the patients, and showed micrometastases in 34.5% and macrometastases in 25.8% of the patients with lung disease. Thyroglobulin (Tg) under thyroxine use was detectable in all patients without antibodies at a cut-off > 1ng/ml, in 90% at > 5ng/ml and in 80% at > 10ng/ml, and after thyroxine withdrawal in 100% at a cut-off > 5ng/ml and in 94% at > 10ng/ml. In the case of patients with antibodies (13.8%), Tg was undetectable in half of them. Diagnostic scanning was positive in 83 and 77.6% of the patients with bone and lung metastases, respectively. After ablative therapy, the sensitivity was 100 and 93%, respectively. Eighty-five percent of patients with a negative diagnostic scan had lung metastases visible on radiographs. The determination of serum Tg is the best method in the follow-up of patients with differentiated thyroid cancer. Elevated Tg levels suggest the presence of metastases, indicating the need for ablative therapy with posttreatment scanning, which might reveal non-apparent metastases