Assessment of the Impact of Radioiodine Therapy of Thyroid Cancer in Postoperative Cases Using Scintigraphy

This study was carried out to assess the Impact of Radioiodine therapy of thyroid cancer in post-operative cases in King Khalid Hospital Saudi Arabia using scintigraphy, it was a descriptive retrospective, and a prospective cross-sectional study was done during the period of June 2016 to February 2018 at King Khalid Hospital Najran included 100 Saudi patients their age ranged (20-75) years old with differentiated thyroid carcinoma who underwent complete thyroidectomy and I131 ablation dose. Pre-therapy diagnostic whole body scintigraphy was done 48 hrs after administration of I131 (3mci) to determine the ablation dose and post therapy whole body scintigraphy was performed 7 days after administration of iodine therapy dose (range 3.3-4.4 GBq) for detection and localization or exclusion of functioning thyroid remnants, persistent or recurrent local disease or distant metastasis in patients receiving I131therapy. All patients came for follow up after 6-12 months to assess the successful of ablation and to identify which patients may require repeat RAIT, the success rate of ablation is determined by negative whole body I131 scan. The results of this study revealed that the mean ageSD of patients was 42.812.6 years (range 2075) years, the most age frequently ranged from 31- 40 years. The most frequently histological type of thyroid carcinoma was papillary thyroid carcinoma. TSH level prior I131 dose was greater than30mIU/L. The mean ablation dose was 100.80 11.9 mCi range from (3.33 to 4.44) GBq (90 to 120 mCi) of I131, with a median follow-up of 1 year (range 6months18 months) with 185 MBq (5 mCi) of I131, from the study group it was seen that follow-up WBS was positive (there is recurrence) in 4 (4.0 %) patients, the majority 96 patients (96.0 %) had negative scans (success of Ablation). The correlation between whole-body scintigraphy finding and age showed that the mean age in the negative and positive scan was 43.06 years, 36.75 years respectively. Correlation between histological type of thyroid carcinoma and age group the papillary thyroid carcinoma was more in age group (31-40) years. The correlation between histological type and gender showed that the most histological type of female and male was papillary thyroid carcinoma repeated 58 and 18 times respectively. The mean ablation dose was 100.83mCi in the negative scan and 100.0mCi in the positive scan. Regarding T stage in T1 48 was negative scan and 3was positive, in T2 26 was negative scan, and there is no positive, in T3 22was negative, and one was positive. In nodal stage, the group with no lymph node invasion 96 was successfully ablated, and 2 with recurrence and group with lymph node involvement 2 with recurrence and there is no negative scan. There was no distant metastasis case in the study group. The mean tumor size was 2.69cm in the negative scan and 2.50 cm in the positive scan. It concluded that papillary thyroid carcinoma was highly response to radioiodine therapy, RT lobe of the thyroid gland was more affected than Lt Lobe and Most of the patients in the study sample were successfully ablated.