Presentation and outcomes of patients with undifferentiated thyroid carcinoma: A national perspective

Background: Undifferentiated thyroid cancer (UTC) accounts for only 1–2% of all thyroid cancers. UTC is one of the most aggressive solid tumors with high metastatic rates and mortality. The objectives of this study are to examine the characteristics of patients with UTC and their overall survival. Methods: Retrospective analysis utilizing the National Cancer Database, 2004–2014 is performed. The study population included adults (≥18 years) patients with UTC or differentiated thyroid carcinoma (DTC), which served as a reference group. Results: A total of 1,870 UTC and 209,707 DTC patients were identified. The median follow-up time of UTC patients was 3.9 months (interquartile range: 1.6–9.0 months). When compared to DTC patients, patients with UTC were more likely to be ≥45-year-old [OR: 48.62, 95% CI: (35.75, 66.14), P<0.001], male [OR: 2.02, 95% CI: (1.84, 2.22), P<0.001], and/or black [OR: 1.27, 95% CI: (1.08, 1.49), P=0.004]. UTC patients were more likely to have Medicaid/Medicare or no insurance and treated in low-volume hospitals (P<0.001). Overall survival in patients with UTC was lower in patients older than 65 years [OR: 1.63, 95% CI: (1.12, 2.38), P=0.011], with multiple comorbidities [OR: 1.65, 95% CI: (1.02, 2.67), P=0.040] and/or presented with metastatic disease [OR: 1.93, 95% CI: (1.71, 2.17), P<0.001]. Compared to thyroidectomy alone, patients without metastasis who received adjuvant radiotherapy and/or chemotherapy had a better overall survival (P<0.001 each). In patients with metastatic disease, any intervention or combination of interventions other than thyroidectomy alone improved survival (P<0.05). Conclusions: Older age, male, and/or black are associated with a higher prevalence of UTC compared to DTC. Although overall survival is poor in UTC, utilization of multi-modal treatment may improve survival.