Characteristics and prognosis of patients with thyroglobulin-positive and radioactive iodine whole-body scan-negative differentiated thyroid carcinoma

Objective: The prognosis of differentiated thyroid carcinoma is generally favorable. However, some patients have negative radioiodine whole-body scans and detectable serum thyroglobulin with biochemical radioiodine-refractory carcinoma and are candidates for treatment with a multikinase inhibitor, such as sorafenib. The purpose of this study is to investigate the characteristics and prognosis of differentiated thyroid carcinoma patients who are thyroglobulin positive and scan negative. Methods: We retrospectively classified 153 patients treated for 15 years by serum thyroglobulin level and radioiodine scan results and examined the relationship between clinical characteristics and prognosis. Results: Overall, 27% of the patients were classified as thyroglobulin positive/scan negative (positive/negative) while 61% were thyroglobulin negative/scan negative (double negative). Compared with double-negative patients, positive/negative patients were significantly older, predominantly male, had a higher pT and pN, stage, and had higher pre-operative thyroglobulin values. Positive/negative patients showed worse prognosis in terms of overall survival, disease-specific survival and disease-free survival than double-negative patients (10-year overall survival, 85 vs. 93%, P = 0.001; 10-year disease-specific survival, 94 vs. 100%, P = 0.03, 10-year disease-free survival, 77 vs. 93%, P < 0.001). Multivariate analysis revealed that positive/negative status was the only factor associated with disease-free survival, including age and TNM stage (hazard ratio: 6.37, 95% confidence interval: 1.22-33.3). However, the median duration of disease-free period for positive/negative patients was 14.2 years. Conclusions: Few patients among thyroglobulin-positive/scan-negative patients are candidates for sorafenib, despite the significant survival differences from double-negative patients.