THE ROLE OF RADIOACTIVE IODINE IN THE TREATMENT OF ADVANCED DIFFERENTIATED THYROID-CARCINOMA

OBJECTIVE I-131 therapy may be beneficial for patients with advanced d ifferentiated thyroid cancer (DTC) but there have been relatively few studies of the prognostic factors which influence the outcome, We have evaluated differences in outcome in relation to histology, localizati on of tumour, differentiation grade, age and sex after I-131 as the on ly secondary treatment for advanced stages of DTC, DESIGN Retrospectiv e study of a selected patient group treated according to a fixed proto col, PATIENTS We studied the outcome in 86 patients with stage pN3, pT 4 or pM1 out of total of 432 patients treated for DTC from 1970 until 1991., RESULTS The overall cure rate of I-131 therapy after a mean fol low-up of 12.1 years was 50% (papillary 65% vs follicular 23%), The ov erall 5-year progression free survival (PFSR) was 66%. Three out of 11 patients with bone metastases from follicular cancer were cured after a mean dose of 13.2 GBq, significantly less than the average dose of 28.4 GBq given to all patients with bone metastases. In the univariate analysis of 5-year PFSR histology (papillary 79% vs follicular 43%), differentiation grade (well differentiated 81% and moderately differen tiated 31%), tumour stage (pN3100%, pT4 77% and M1 48%), and age (less than or equal to 60 years 85% vs >60 years 46%) were significant prog nostic factors. A multivariate analysis showed differentiation grade, histology and age to be significant prognostic variables for outcome ( moderately vs well differentiated: RR = 3.16, follicular vs.papillary: RR = 2.56 and age >60 vs age less than or equal to 60: RR = 2.43), CO NCLUSIONS I-131 can be an effective treatment in patients with advance d differentiated thyroid cancer at all sites and can cure, on average, 50% of all patients with advanced differentiated thyroid cancer.