| Abstract [eng] |
Justification: Thyroid cancer is a widespread malignancy of the endocrine system, the incidence of which is rising year by year, yet mortality from thyroid cancer remains low. Aim of the study: To assess the epidemiological patterns of thyroid cancer and iodine intake patterns. Objectives of the study: 1. To determine the dynamics of thyroid cancer incidence in the period 1990-2019; 2. To determine the dynamics of thyroid cancer mortality between 1993 and 2022; 3. To assess thyroid cancer survival rate in the period 1992-2017; 4. To identify patterns of iodine intake over the period 2002-2018 based on neonatal thyroid-stimulating hormone (TTH) levels. Methods: Data on 7753 people with thyroid cancer between 1990 and 2019 from the National Cancer Institute registry centre were analysed. Data on thyroid cancer are standardised for the European and world populations using a direct standardisation method. Average annual changes in morbidity and mortality rates were estimated using JOINPOINT. Survival analysis was performed in IBM SPSS Statistics, using the Kaplan-Meier method and the log-rank test was used to compare groups. Anonymized 492,143 newborns born in Lithuania between 2002 and 2018 were analysed as part of a global newborn screening for congenital hypothyroidism. Differences were considered statistically significant when the p-value was <0.05. Results: The European standardised incidence rate of thyroid cancer in men has increased from 1.42 to 4.45 cases per 100,000 population between 1990 and 2019. The average annual percentage change (AAPC) of thyroid cancer in men increased statistically significantly by 4.11% per year (95% PI: 3.21-5.01; p<0.05). The European standardised incidence rate of thyroid cancer in women has increased from 3.75 to 12.24 cases per 100,000 population between 1990 and 2019. Statistically significant increase of 5.14% per year was observed in women's AAPC (95% PI: 3.87-6.42; p<0.05). The European standardised male mortality rate has declined from 1.08 to 0.88 per 100,000 population between 1993 and 2022. In men, the AAPC decreased significantly by 3.41% per year (95%CI: -5.86- -0.88; p<0.05). The standardised mortality rate for thyroid cancer in women decreased from 1.69 to 0.95 cases per 100,000 population between 1993 and 2022. In women, the annual decrease in AAPC was significantly lower by 2.01% (95%PI: -2.81- -1.19; p<0.05). In terms of survival probability, for the period 1992-2017, those diagnosed with early-stage cancer were the most likely to survive: 87.3% of patients diagnosed with stage 1 cancer survived over the five-year period, while those diagnosed with stage 4 cancer survived 21.6%. In terms of morphology, those with papillary thyroid cancer had the highest probability of survival (survival rate of 78.8%) and those with anaplastic thyroid cancer had the lowest probability of survival (12.1% survived). The prevalence of neonatal TTH readings of more than 5 mIU/l ranged from 1.21% (2013) to 5.43% (2004) between 2002 and 2018. Comparing data from 2002 and 2018, the observed prevalence of neonatal TTH values above 5 mIU/l decreased by 57% (p<0.05). Conclusion: 1. The incidence of thyroid cancer in Lithuania has been increasing from 1990 to 2019, with a statistically significant average annual percentage change of 4.11% in men and 5.14% in women. 2. The mortality rate from thyroid cancer in Lithuania has been decreasing from 1993 to 2022, with a statistically significant annual average percentage change of 3.41% in men and 2.01% in women. 3. Survival after thyroid cancer diagnosis in Lithuania in 1992-2017 depended on the stage and morphological form. The survival rate was highest among those with stage 1 papillary thyroid cancer and lowest among those with stage 4 anaplastic thyroid cancer. 4. The 57% decrease in the incidence of neonatal TTH values above 5 mIU/l between 2002 and 2018 indicates that iodine intake in the population is improving. |
