Risk of Mortality between Untreated and Treated Papillary Thyroid Cancer: A Matched Cohort Analysis

Objectives: To examine the association between treatment status and mortality risk among patients with papillary thyroid cancer (PTC). Methods: We identified 3,679 adults with PTC. Thirty-one untreated patients were matched to 155 treated patients. Hazards ratios (HR) and 95% confidence intervals (CIs) were calculated to estimate all-cause and disease-specific mortality. A low-risk subgroup was analyzed for differences in all-cause mortality. Results: The adjusted HRs (95% CIs) for all-cause mortality at 5 and 10 years were 4.2 (1.7-10.3) and 4.1 (1.9-9.4) and for disease- specific mortality were 14.1 (3.4-59.3) and 10.2 (2.9-36.4), respectively, for untreated versus treated patients. The adjusted HRs (95% CIs) for all- cause mortality was 0.7 (0.1-6.4) for low-risk untreated versus matched treated patients. Conclusions: Compared to treated patients, untreated PTC patients were at higher risk of death while low-risk untreated PTC patients had comparable rate of metastasis and no increased risk of all-cause mortality. Level of evidence: 3