Predictive Value of Thyroglobulin Changes for the Curative Effect of Radioiodine Therapy in Patients With Metastatic Differentiated Thyroid Carcinoma

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the publication of the American Thyroid Association's guidelines for the management of these disorders was published in 2006, a large amount of new information has become available, prompting a revision of the guidelines. Relevant articles through December 2008 were reviewed by the task force and categorized by topic and level of evidence according to a modified schema used by the United States Preventative Services Task Force. The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to optimal surgical management, radioiodine remnant ablation, and suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using ultrasound and serum thyroglobulin as well as those related to management of recurrent and metastatic disease. We created evidence-based recommendations in response to our appointment as an independent task force by the American Thyroid Association to assist in the clinical management of patients with thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Differentiated thyroid cancer has a good prognosis and only rarely presents with distant metastasis at diagnosis. The clinical outcome of this presentation was assessed with respect to survival and factors that may determine prognosis. A retrospective review was undertaken of patients with stage M1 differentiated thyroid cancer at presentation (n = 49), referred from 1980-2000 at a single institution. The median age was 68 (range, 17-90), with 69% females. The initial site(s) of metastasis were lung only, 45%, bone only, 39%, other single site, 4%, and multiple sites, 12%. papillary, 51%, follicular, 49%. Initial treatment(s) included: thyroidectomy, 82%, radioactive iodine (RAI), 88%, excision of metastasis, 29%, radiotherapy, 47%, and chemotherapy, 6%. With a median follow-up time of 3.5 years, 25 patients are alive (51%) and 24 died (49%), with 3-year and 5-year actuarial survivals of 69% and 50%, respectively. Only a minority of patients (4/25, 16%) had no clinical evidence of disease at last follow-up. Most deaths (17/24, 71%) were due to progressive cancer. Prognosis was associated with age, site of metastasis, histology, and iodine avidity of the metastasis. Patients aged 45 years (P = .001). The 3-year survival for lung only versus bone only metastasis was 77% versus 56% (P = .02); for papillary versus follicular carcinoma, 75% versus 62% (P = .006); for iodine-avid disease (n = 29) versus not avid (n = 14), 82% versus 57% (P = .02), respectively. In multivariate analysis after adjusting for age, only histology and iodine avidity remained significant for survival. The hazard ratio for follicular histology was 3.7 (95% confidence interval [CI], 1.1-12.1, P = .03), and for tumors not avid for iodine, 3.4 (95% CI, 1.2-9.2, P = .02). The data support the aggressive management of patients presenting with stage M1 thyroid cancer, with thyroidectomy and RAI. Complete clinical eradication of disease was rarely seen, and 50% of patients survived for more than 5 years. Young patients with papillary tumors and/or iodine-avid disease have an even better prognosis.