Variants and pitfalls on radioiodine scans in pediatric patients with differentiated thyroid carcinoma

Paediatric differentiated thyroid carcinoma: a UK National Clinical Practice Consensus Guideline

This guideline is written as a reference document for clinicians presented with the challenge of managing paediatric patients with differentiated thyroid carcinoma up to the age of 19 years. Care of paediatric patients with differentiated thyroid carcinoma differs in key aspects from that of adults, and there have been several recent developments in the care pathways for this condition; this guideline has sought to identify and attend to these areas. It addresses the presentation, clinical assessment, diagnosis, management (both surgical and medical), genetic counselling, follow-up and prognosis of affected patients. The guideline development group formed of a multi-disciplinary panel of sub-speciality experts carried out a systematic primary literature review and Delphi Consensus exercise. The guideline was developed in accordance with The Appraisal of Guidelines Research and Evaluation Instrument II criteria, with input from stakeholders including charities and patient groups. Based on scientific evidence and expert opinion, 58 recommendations have been collected to produce a clear, pragmatic set of management guidelines. It is intended as an evidence base for future optimal management and to improve the quality of clinical care of paediatric patients with differentiated thyroid carcinoma.

Prognostic value of star-shaped intense uptake of 131I in thyroid cancer patients

OBJECTIVE

After ¹³¹I treatment in patients with differentiated thyroid carcinoma (DTC), we sometimes find a star-shaped intense uptake of ¹³¹I on therapeutic whole body scans (Rx-WBS), called star artifacts. Therefore, we analyzed the relevant clinical factors and prognostic value of star artifacts in DTC patients.

METHODS

809 DTC patients who received ¹³¹I treatment were retrospectively evaluated and divided into 2 groups of patients with and without star artifacts. We evaluated the therapeutic response which was divided into excellent response (ER), biochemical incomplete response (BIR), indeterminate response (IR), and structural incomplete response (SIR). Clinical factors for the presence of star artifacts were analyzed. We also compared the rate of ER, BIR, IR, SIR and recurrence rate between group 1 and group 2.

RESULTS

The major clinical factors included stimulated thyroglobulin (sTg)>1.8ng/ml, 24h radioiodine uptake (RAIU)>2.2%, and positive ^99mTcO4^- thyroid imaging for the presence of star artifacts. In patients with sTg levels>10ng/ml, patients in group 1 had a higher rate of ablation success and ER than patients in group 2 (80.2% vs 65.6%, P=0.038, 31.6% vs 13.1%, P=0.008, respectively) and had a similar rate of BIR, IR, SIR. Recurrence rate was similar between group 1 and group 2 (5.2% vs 3.1%, P=0.13).

CONCLUSION

More remnant thyroid tissue is one of the factors associated with the presence of star artifacts on Rx-WBS. Patients with star artifacts exhibit a better therapeutic response (ER) when sTg levels are >10ng/ml. However, star artifacts have no effect on the recurrence rate.

The clinical meaning of pre- and post-ablation thyroglobulin levels at first radioiodine therapy in patients with papillary thyroid cancer

BACKGROUND/AIMS

This study was conducted to identify prognostic factors in patients with papillary thyroid cancer (PTC) at the time of first radioactive iodine (RAI) therapy, and to evaluate the clinical value of the thyroglobulin (Tg) increase after RAI.

METHODS

Serum Tg was sampled prior to (pre-Tg) and 7 days after RAI (post-Tg) in 680 patients with PTC. Patients were classified into excellent response (ER), biochemical incomplete response (BCIR), structural incomplete response (SIR), and indeterminate response (IR) groups using dynamic risk stratification at 6 to 18 months after RAI therapy.

RESULTS

After RAI therapy, 514 patients (75.6%) had an ER, 34 (5.0%) had a BCIR, 13 (2.0%) had an SIR, and 119 (17.5%) had an IR. Pre-Tg level was significantly different among the groups, with the highest level being in the SIR group, followed by the BCIR, IR, and ER groups. However, post-Tg levels were not different among the groups. Post-Tg level increased significantly after RAI therapy compared to the pre-Tg level (mean 13.8 ± 32.2 ng/mL vs. 2.5 ± 8.9 ng/mL). In 422 patients whose pre-Tg level was < 1 ng/mL, 205 had post-Tg levels < 1 ng/mL, while 167 had post-Tg levels of 1 to 10 ng/mL, and 50 had levels > 10 ng/mL. No difference was observed in the response to therapy. Differences in RAI dose and uptake pattern were observed among the three groups.

CONCLUSION

Pre-Tg was useful as a prognostic factor in patients with PTC. In patients with low pre-Tg, increased post-Tg may reflect remnant tissue and does not help predict the prognosis.

Initial treatment of pediatric differentiated thyroid cancer: a review of the current risk-adaptive approach

Differentiated thyroid cancer in children is a rare disease, accounting for only 1.4% of all pediatric malignancies. The diagnosis, biological behavior and treatment of differentiated thyroid cancer in children is different from that in adults. While there are many unresolved issues regarding approaches to management of differentiated thyroid cancer in the pediatric population, there is near universal consensus that treatment of this disease, which includes total thyroidectomy, central lymph node dissection at the time of initial surgery in those with nodal metastases, and the possible use of iodine-131 radiotherapy, is best performed by specialists including high-volume endocrine surgeons and experts with experience in calculating and administering radioactive iodine in children, when deemed appropriate.