Prognostic Implications of Radioiodine Avidity and Serum Thyroglobulin in Differentiated Thyroid Carcinoma with Distant Metastasis

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 303-321-Cancer in Endocrine Tissues
Bench to Bedside
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-307
Seo Young Sohn*, Hye Jeong Kim, Na Kyung Kim, Ji Young Joung, Yoon Young Cho, Hyun Kyung Tan, Sun Wook Kim and Jae Hoon Chung
Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
Background: Although differentiated thyroid carcinoma (DTC) rarely develops distant metastases, the present study was performed to evaluate factors that impact the survival of those patients with DTC who present with distant metastasis.

Methods: Among 4,989 patients who underwent thyroid surgery for DTC, 82 patients presenting with distant metastasis were analyzed. Based on radioiodine (131I) avidity and TSH-stimulated serum thyroglobulin (sTg) level at the time of metastasis, patients were divided into three groups: group 1 (131I uptake + sTg ≤ 215 ng/mL, n=46), group 2 (131I uptake + sTg > 215 ng/mL, n=24), and group 3 (no 131I uptake, n=12). Disease-specific survival was estimated using the Kaplan-Meier method. Factors predictive of the outcome were evaluated using Cox proportional hazard regression analysis.

Results: With a median follow-up after surgery of 72 months, the 5-year and 10-year disease-specific survivals for all patients were 78% and 69%, respectively. The predictors of survival were associated with age (p=0.004), symptoms at the time of presentation (p=0.045), histology (p=0.01), sites of metastasis (p=0.03), and 131I avidity and sTg level at the time of metastasis (p=0.002). In multivariate analysis after adjusting for prognostic variables, only 131I avidity and sTg level at the time of metastasis remained significant factors for survival.

The age of patients differed significantly between the groups, with mean ages of 45 years, 49 years, and 57 years for group 1, group 2, and group 3, respectively (p=0.04). The frequency of follicular thyroid carcinoma was significantly higher in group 2 (54%) compared with either group 1 (15%) or group 3 (17%) (p=0.002). The median tumor size was largest in group 2 (4.5 cm), followed by group 3 (3.4 cm), and group 1 (2.0 cm) (p<0.001). The number of multiple metastatic sites was higher in group 2 (46%) compared with either group 1 (9%) or group 3 (8%). About half of patients in group 1 achieved remission status, whereas no patients in groups 2 and 3 were in remission.

Conclusion: Certain DTC patients with distant metastasis demonstrate favorable outcomes dependent on 131I avidity and sTg level at the time of metastasis.

Nothing to Disclose: SYS, HJK, NKK, JYJ, YYC, HKT, SWK, JHC

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