Trends in papillary thyroid cancer mortality in Denmark according to stage and education

Objective
Few studies exist on trends in papillary thyroid cancer (PTC) survival and mortality according to stage and level of socioeconomic status.

Design
Nationwide cohort study.

Patients and Measurements
Patients diagnosed with PTC during 2000–2015 in Denmark were identified from the Danish Cancer Registry and followed until the end of 2020. We evaluated 5-year all-cause mortality and relative survival according to stage and 5-year mortality rates with corresponding average annual percentage changes (AAPCs) according to stage and education. Finally, we assessed the association between several factors and mortality of PTC using Cox regression.

Results
For the 2006 cases of PTC diagnosed during 2000–2015, relative survival tended to increase and mortality rates tended to decrease for all stages. For localized PTC, mortality rates tended to decrease among individuals with medium education (AAPC = −7.0, 95% confidence interval [CI]: −14.7 to 1.5), but showed an increasing pattern among individuals with long education (AAPC = 19.8, 95% CI: −4.2 to 50.0). For nonlocalized PTC, mortality rates showed a decreasing tendency among individuals with medium and long education (AAPC = −5.5, 95% CI: −13.2 to 2.9, and AAPC = −10.4, 95% CI: −20.8 to 1.4, respectively). Being diagnosed with PTC in a more recent calendar period and long education were associated with a lower mortality rate in the Cox regression analysis.

Conclusions
A pattern of an increasing relative survival and decreasing mortality rates of PTC across all stages was seen in Denmark during 2000–2015. The decreasing pattern in mortality rates was most evident in individuals with localized stage and medium education, and in individuals with nonlocalized stage and medium or long education.