Analysis of the factors affecting the efficacy of (131)I remnant ablation in patients after thyroidectomy for papillary thyroid microcarcinoma

Abstract

Objective: To investigate the influential factors of efficacy of the first (131)I ablation therapy for thyroid remnant in papillary thyroid microcarcinoma (PTMC) patients after thyroidectomy. Methods: Eighty-nine PTMC patients who underwent twice (131)I ablation therapy and (131)I whole body follow-up scan ((131)I-WBS) within 5 to 8 months in our department from September 2007 to October 2016 were identified and enrolled in present study. Patients were divided into complete-ablation group and uncomplete-ablation group according to whether or not radioactivity was detected at the thyroid bed in (131)I-WBS. The χ(2) test and multi-variance Binary logistic regression were performed for the factors which might affect the therapeutic efficacy. Results: The first (131)I ablation therapy was successful in 41 of 89 patients (46.07%). Residual thyroid weight was found to be associated with therapeutic efficacy (P<0.05), while gender, age, surgical method, lesions'maximum diameter, with or without LN metastasis, with or without distant metastasis, time of operation from first (131)I treatment, lesions'number, thyroid stimulating hormone (TSH), thyroglobulin (Tg), the consistency of (131)I-WBS and (99)Tc(m)-pertechnatate, TNM stage, ATA risk, Tg/TSH ratio were not significant associated with therapeutic efficacy. Binary logistic regression analysis was performed in these respects and it indicated that residual thyroid weight and ATA risk were not statistically significant independent variable (P>0.05). Conclusions: Residual thyroid weight might affect efficacy of the first (131)I ablation therapy on thyroid remnant in PTMC patients after thyroidectomy, but it is not an independent factor. Multiple interrelated factors should be considered when predicting the efficacy of the first (131)I ablation therapy.