Efficacy of posttreatment radioiodine scanning in patients with differentiated thyroid cancer

Background: Differentiated thyroid cancers often require radioiodine treatment followed by posttreatment scan. We aimed in this study to assess the utility of the posttreatment radioiodine scan in this population. Methods: An analysis of patients who received radioiodine treatment at Rambam Campus, during 2006-2013. Scans showing remnant normal thyroid tissue were considered as normal. Positive uptake was defined as uptake in the lateral neck or distant sites. Results: A total of 455 patients were analyzed, 68% had T1-T2 and 28% had positive lymph nodes. Positive uptake in the lateral neck was recorded in 52 (11.4%) and in distant sites in 41 (9%) patients. Tracheal invasion, esophageal invasion, nerve invasion, and N1b classification were associated with a positive scan (P <.05). A positive radioactive iodine scan was not related to poor prognosis. Conclusions: Posttreatment scans are positive in only 20% of patients. Locally invasive tumor and positive nodes are associated with positive scans.