Factors influencing successful radioiodine therapy of thyroid

Abstract

Background: Well-known fact is that the good surgical treatment, leaving only small residuals of thyroid tissue, is the outmost valid predictive factor of successful ablative radioiodine treatment. Assuming that all patients had state of the art surgical treatment, with this study we tried to evaluate other possible predictive factors of successful radioiodine therapy after total thyroidectomy. Methods: Total of 56 patients (15 males and 41 females mean age 43.37?13), operated during the year 2001 was evaluated. Due to differentiated carcinoma of the thyroid total thyreoidectomy was done in 7 with follicular and in 49 patients with papillary cancer. Forty-one patients received ablative 131 I dose (3.7GBq) and fifteen patients received therapeutic dose (5.55GBq) of radioiodine therapy. As possible predictive factors the TNM classification (T1, 6; T2, 17; T3, 4; T4, 28 and 24 with N0 and 32 with N1), the number of foci on whole body scan (WBS), and the serum level of thyroglobulin were statistically evaluated. One year after radioiodine therapy control WBS was done and successful outcome of the therapy was considered to be the WBS without visible accumulation of radioiodine and with low serum level of thyroglobulin. Results: Outcome of ablative radioiodine therapy was considered as successful in 55.4% patients and 44.6% of patients needed additional radioiodine therapies. Only the number of foci and the level of thyroglobulin showed statistically significant (p(0.05) influence on the outcome of applied radioiodine therapy. Conclusion: Significant influence of the thyroglobulin level and number of foci on the WBS in patients with total thyroidectomy could be explained by the fact that there were the signs of minimum thyroid residual tissue, and that there were no microscopic spread of disease.