P. H. Dedhia1, S. Grzegorski1, M. S. Cohen1, B. S. Miller1, P. G. Gauger1, D. T. Hughes1 1University Of Michigan,Surgery,Ann Arbor, MI, USA
Introduction: Radioactive iodine (RAI) ablation is frequently used in patients with papillary thyroid cancer (PTC) larger than 1 cm to ablate the thyroid remnant and facilitate detection of recurrent disease. Treatment with RAI is usually performed 6-8 weeks after thyroidectomy. Here we assess the effect of delay in RAI on post-RAI thyroglobulin levels and PTC recurrence.
Methods: This is a retrospective review of 447 patients with pathologically confirmed PTC from thyroidectomy procedures performed between 2009 to 2013 in the endocrine surgery division at the University of Michigan. Clinical characteristics, pathology, postoperative stimulated thyroglobulin (Tg) levels, days elapsed from surgery to radioactive iodine treatment, unstimulated Tg levels after RAI, and recurrence were examined.
Results: Of the 447 patients with papillary thyroid cancer from 2009 to 2013 who underwent thyroidectomy, 50.5% (n=226) were treated with RAI. Of the patients treated with RAI, 37% of patients underwent RAI greater than 60 days after thyroidectomy. The average tumor size in patients treated with immediate RAI and patients who underwent delayed RAI were 2.2 cm and 2.1 cm, respectively. 89% of patients with immediate RAI had undetectable Tg compared to 83% of patients with delayed RAI (p=0.20). Of patients that underwent immediate RAI, 5.9% (n=8) developed recurrence, whereas 2.5% of patients undergoing delayed RAI developed recurrence (n=2; p = 0.25).
Conclusion: Administration of RAI in a delayed manner is not associated with decreased likelihood to achieve undetectable Tg or with increased recurrence of PTC after RAI treatment.