Decreasing trend in thyroid cancer incidence: a study from central Italy (2007-2019).

Area of Science:

• Oncology
• Epidemiology
• Public Health

Background:

• Thyroid cancer (TC) incidence has risen in high-income nations due to overdiagnosis.
• Efforts to curb this trend began mid-2010s, necessitating data on incidence changes.
• Understanding TC trends is crucial for effective public health strategies.

Purpose of the Study:

• To analyze TC incidence trends in Italy's Lazio Region from 2007-2019.
• To evaluate the impact of the 2014 Italian Consensus for the Classification and Reporting of Thyroid Cytology (ICCRTC) on TC diagnosis.
• To identify changes in TC diagnosis patterns post-ICCRTC implementation.

Main Methods:

• Population-based study using Lazio Region Cancer Registry data (5.8 million residents).
• Calculated annual age-standardized incidence rates for TC (both sexes).
• Applied segmented linear regression to interrupted time-series (ITS) to assess ICCRTC's impact on monthly incidence.

Main Results:

• A significant decline in annual TC incidence rates observed over 13 years, more pronounced in females.
• Results align with international findings from the US and South Korea.
• A notable reduction in TC incidence for both sexes was detected after ICCRTC implementation in 2014.

Conclusions:

• Significant decrease in TC incidence, particularly in females, was observed.
• ITS analysis suggests ICCRTC played a role in reducing overdiagnosis.
• Findings from Lazio Region are likely generalizable to the Italian national level.