Follow-up protocol in differentiated thyroid cancer: Is repeated whole body Iodine scintigraphy necessary? "A 20 years review

Abstract

Introduction: Thyroid cancer follow up protocol has recently been reviewed globally, in this study; we present a 20years descriptive retrospective study from a tertiary hospital. Method: A total of 106 patients who met the inclusion criteria out of287 patients treated with radioactive iodine post thyroidectomy for differentiated thyroid carcinoma were reviewed. Result: There were 91 female and 15 male; M: F of 6:1. The mean age of the patients was 45 years (range: 16- 81 years). Papillary thyroid cancer was the most common 58 (55%) then follicular 30 (28%), Hurthle cell 10(9%) and the mixed papillary- follicular 8 (8%) types. The mean ages of occurrenc e of papillary, follicular, Hurthle and Mixed papillary and follicular cancers were 40,49,53 and 49 years respectively More than half of the patients 58 (53.7% ) had total thyroidectomy, while 36(34%), and 12( 11.3%) patients had near total thyroidectomy and lobectomy respectively. The proportion of patients with negative whole body iodine scan after radioactive iodine ablation (RIA) increased progressively from 57 to 98%, 6-24 months of follow up. The mean iodine dose administered by the 1st 6 month of follow-up was 80mCi (range 30-200mCi) compared to total dose of 429mCi in patients that received multiple treatment (range 220-1160 mCi) At the end of first iodine treatment, 58 patients out 100 were Iodine scan negative. The remaining 42 patients became negative by the 4th treatment. Most patients had undetectable Tg level at 24 months, with a small proportion 17 out of 51 (33.3%) with significantly elevated Tg among the Tg >2ng/ml group. Negative iodine scan andTg level were concordant in 89 (72.1%) of the patients studied at 24 month and discordant in 12 (11.9%) patients. There was no tumour recurrence or rebound serum Tg up till the 24 month follow up period