Multifocal papillary thyroid cancer in children and adults. Lecture

Thyroid cancer is the 9th most common cancer in the world. Thus, in the year 2020, 586.000 cases of thyroid cancer were registered worldwide. The incidence rate among women is 10.1 per 100 thousand population, and among men — 3.1 per 100 thousand population. In Ukraine, in 2019, the standardized rate of incidence of thyroid cancer (world standard) was 6.9 per 100.000 population (2.8 among men, 10.5 among women). In the structure of the incidence of malignant neoplasms of the cervical spine, thyroid cancer ranks first place among women aged 18 — 29 (19.9 %), fourth among both men aged 18 — 29 (8.3 %, and women aged 30 — 54 (8.1 %). Over the past 40 years, increased incidence of thyroid cancer (in particular, papillary thyroid cancer) is observed in most countries, which can be explained by various factors, for example, overdiagnosis, a change in the prevalence of modified risk factors. In Ukraine, in the period from 1989 to 2012, the rate of incidence of papillary thyroid cancer among men increased by 115 %, among women — by 137 %, the annual increase in incidence of papillary thyroid cancer for men and women was 5 and 6 %, respectively. Multifocality in papillary thyroid cancer is a characteristic feature that is much more common in pediatric patients than in adults, but the number of studies in children is limited, which is associated with a lower prevalence of the disease in children. The results of investigations on the multifocality predictors and its role in influencing relapse, persistence, and survival in patients with papillary thyroid cancer are conflicting in both adults and pediatric population. Among the risk factors of multifocality, a smaller number of controversies concerns the links of metastasis in the lymphatic nodes, radiation in the anamnesis, childhood age, and for bilaterality — multifocality of the primary lobe and the presence of contralateral benign nodes (in adults). Other factors as predictors of multifocality have controversial significance and deserve attention in further research. The identification of reliable predictors of multifocality, especially with the help of preoperative data analysis, as well as multifocality risk stratification will facilitate the complex decision‑making process for the correct treatment tactics of children and adults with papillary thyroid cancer.