The incidence trends of papillary thyroid carcinoma in Belarus during the post-Chernobyl epoch.

BACKGROUND

The increase of papillary thyroid cancer (PTC) rate among children who were exposed to post-Chernobyl 131-I release was reported only four years after the accident, first in Belarus where the heaviest fallout happened. The evolution of the occurrence of thyroid carcinoma based on the age-period-cohort analysis and the effects of age, period, and birth cohort on time trends aimed to reveal if post-Chernobyl follicular cells irradiation still has been impacting on incidence rate of papillary thyroid carcinoma nowadays.

METHODS

The Belarusian Cancer Registry was used to identify patients with PTC diagnosed during the years 1980-2019. The incidence trends were analysed using Join-point regression software.

RESULTS

The highest peak of age-specific incidence curve was shown during the years 1980-2001 in the age group of 15-19 years old that was associated also with short-latency cases of post-Chernobyl PTC. This is the same age group that demonstrated significant growth of the incidence rate during the years 2006-2019, largely because of the increasing number of non-exposed patients with PTC (p < 0.001). Influence of post-Chernobyl exposure also can be seen in the young adults age-groups of patients (for 20-24 years old during the years 1980-2003 and 2013-2019, p < 0.001; for 25-29 years old during the years 1980-1999 and 1999-2011, p < 0.001).

CONCLUSION

After the Chernobyl accident, epidemiological waves that reflect the age shift of the group of children exposed to 131-I have consistently emerged. Currently, the incidence rate continues to increase only in the cohort of patients aged 20-44 years.