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Radiology Life • February 2017

12 | ADVANCE FOR RADIOLOGY LiFE | CANCER THERAPY / A post-operative stimulated thyroglobulin (Stim-Tg) and neck ultrasound were performed approximately three months after thyroidectomy. Patients were divided into three subgroups based on their initial Stim-Tg level: less than 1, 1–5, and greater than 5 μg/L. Patients with Stim-Tg measurements less than 1 μg/L were informed that there was no indication for RAI therapy and that the surgical procedure for them was likely curative. Patients with a Stim-Tg greater than 5 μg/L were strongly advised to proceed with RAI therapy given an increased individual risk of residual/recurrent PTC.19 Patients with Stim-Tg greater than 1 μg/L but less than 5 μg/L who had a negative neck ultrasound were advised that their Stim-Tg may represent a small remnant of normal thyroid tissue and required active surveillance to validate the absence of residual thyroid cancer, including the potential need for RAI in the future. All patients were followed on long-term thyroid hormone TSH-suppression therapy with repeat neck ultrasound, as well as stimulated and basal thyroglobulin measurements every 6-12 months. All patients who received RAI underwent a posttreatment whole-body scan (WBS) seven days after treatment. Using the PRSP, a total of 129 low/intermediate risk PTC patients were followed prospectively for a mean duration of 6.2 years. Among patients in the study19, the female-to-male ratio was approximately 3:1, with a mean age of 51 years at the time of thyroidectomy. The majority of patients (63%) were greater than 45 years of age. An initial total thyroidectomy was performed in the majority of patients (78%), whereas the rest underwent a completion thyroidectomy. A therapeutic central compartment neck dissection was performed in a minority of patients (7%). The mean tumor size was 2.5 cm (SD 1.4 cm); however, several patients (16%) had tumors greater than 4 cm in this low/intermediate-risk cohort. Study Findings In the cohort of 129 PTC patients, risk stratified as low/intermediate risk on the basis of surgical pathology, results of the study showed that 116 (90%) were able to avoid unnecessary RAI using the PRSP, with virtually no risk of residual/recurrent disease with a mean prospective follow-up of 6.2 years. (A single patient who had evidence of residual/recurrent disease was correctly identified to receive RAI using the PRSP.) The overall risk for residual/recurrent PTC was less than 1%. A subsequent two-year follow-up on this cohort has shown that no new patient has required RAI. Taken together, the study of Orlov et al19 provides the first long-term prospective study cohort with a mean follow up of over eight years that supports using serial post-operative stimulated thyroglobulin and neck ultrasound as personalized methods for risk stratification and radioactive iodine selection in low- and intermediate-risk papillary thyroid cancer. Results showed that the vast majority of patients, stratified to be low/intermediate-risk PTC on the basis of their surgical pathology, were able to avoid RAI using the proposed postoperative Stim-Tg and neck ultrasound personalized criteria. These observations demonstrate that traditional risk factors previously considered to favor RAI treatment are not always concordant with this personalized strategy, and may lead to overtreatment. Paul Walfish is an endocrinologist specializing thyroid physiology and pathology at Mount Sinai Hospital These observations demonstrate that traditional risk factors previously considered to favor RAI treatment are not always concordant with this personalized strategy.” FEBRUARY 2017


Radiology Life • February 2017
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