Terapia empírica del cáncer de tiroides con I-131 como estrategia diagnóstica para identificar lesiones ocultas en pacientes con tiroglobulina elevada sin enfermedad estructural identificable

Abstract

Objectivesa) To establish the prevalence of positive post-therapeutic I-131 whole-body scan (PWBS) results in patients with elevated thyroglobulin (Tg) levels and with no structurally identifiable disease; b) to calculate stimulated and suppressed Tg cut-off values with the highest accuracy using ROC analyses; c) to describe positive PWBS-related clinical and histopathology factors. MethodsA retrospective assessment is presented of PWBS results in 40 patients (34 female) between 14 and 74 years of age with differentiated thyroid cancer (DTC) who were treated with empirical radioiodine therapy at the Instituto Nacional de Cancerología between 2003 and 2009, and with a stimulated Tg ≥ 10 ng/ml with no structurally identifiable disease. ResultsPWBS revealed a pathological uptake in 24 (60%) patients. The highest diagnostic accuracies of serum Tg for abnormal I-131 uptake in PWBS were 1.89 ng/ml for suppressed Tg and 25 ng/ml for stimulated Tg. Factors such as age ≥ 45 years, aggressive variants, and other poor outcome predictors, tumor size > 4cm, extra-institutional first surgery, postoperative thyroglobulin >30 ng/ml and structurally incomplete tumor response to initial treatment, were more frequently related to positive PWBS. ConclusionPWBS is a diagnostic strategy that provides localizing, metabolic and prognostic information in most patients with elevated Tg levels and with no structurally identifiable disease.