Recent insights into trends of thyroid cancer incidence in Lithuanian population exposed to Chernobyl fallout early in life

• Published in: Ecotoxicology and environmental safety Vol. 283; p. 116789
• Main Authors: Steponaviciene, Rita, Maceika, Evaldas, Kesminiene, Ausrele, Smailyte, Giedre
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 15.09.2024; Elsevier
• Subjects: Adolescent; Adult; Chernobyl accident; Chernobyl Nuclear Accident; Child; Child, Preschool; Children, adolescents; Dosimetry; Female; Humans; Incidence; Infant; Infant, Newborn; Iodine Radioisotopes; Ionizing radiation; Lithuania; Lithuania - epidemiology; Male; Neoplasms, Radiation-Induced - epidemiology; Radiation Exposure - adverse effects; Radioactive Fallout - adverse effects; Retrospective Studies; Thyroid cancer incidence; Thyroid Neoplasms - epidemiology; Young Adult; Lithuania; Ionizing radiation; Dosimetry; Thyroid cancer incidence; Lithuania; Chernobyl accident; Children, adolescents
• ISSN: 0147-6513; 1090-2414; 1090-2414
• DOI: 10.1016/j.ecoenv.2024.116789

In the last three decades, an increase in thyroid cancer incidence has been observed worldwide, as well as in Lithuania. Although the rise was linked to overdiagnosis, the role of lifestyle and environmental factors, including exposure to ionizing radiation, cannot be excluded. In our retrospective study, we aimed to assess the association between the average age-specific thyroid dose due to the radioactive iodine uptake during childhood and adolescence from the Chernobyl fallout in Lithuania, and the trends of incidence of thyroid cancer from 1991 to 2015 in different regions. Averaged age-dependent thyroid doses were estimated for every municipality based on radioiodine activity in milk, reconstructed from available 131I activity measurements in the grass. Thyroid cancer incidence rates were calculated for the entire population and for two age at the time of exposure groups: 0–19 years and 0–9 years. Thyroid cancer relative risk (RR) was estimated for three municipality-specific thyroid dose (for 0-year-old babies) categories: less than 100 mGy (reference group), 100–199 mGy, and ≥200 mGy. Over the study period (1991–2015), a total of 5664 cases of thyroid cancer were registered in the entire Lithuanian population; 817 cases in the age group from 0 to 19 years at the time of the Chernobyl accident, and 266 cases in the age group from 0 to 9 years. Age-standardized thyroid cancer incidence rates have notably increased since 2000, peaked in 2009 (especially in females), and then slightly decreased and stabilized. The estimated average municipality-specific age-dependent thyroid doses ranged from 270 mGy in western Lithuania to 1.5 mGy in central and northern Lithuania. For the age group of 0–19 years at the time of the accident, in the period 1991–1995, the thyroid cancer relative risk was significantly increased (RR 3.91; 95 % CI: 1.27–10.29, p=0.01) in the highest dose category, compared to the lowest (although based on a small number of cases). For the age group 0–9 years at the time of the accident, a tendency of increased RR in the highest dose category appeared in the most recent period, 2011–2015. Our observations need to be confirmed by further following trends of thyroid cancer incidence in the cohort of 0–19-year-old Lithuanians at the time of the Chernobyl accident. •The Chernobyl disaster had a long-term health impact on those exposed to radiation early in life.•The effects of this accident were far-reaching and continue to be studied to this day.•Reconstructed dose of 131I to the thyroid showed a wide range variation among Lithuania’s regions.•In areas with doses over 200 mGy in early life, thyroid cancer rates increased for both sexes.