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.