One of the major health consequences of the Chernobyl Nuclear Power Plant accident in 1986 was a dramatic increase in incidence of thyroid cancer among those who were aged less than 18 years at the time of the accident. This increase has been directly linked in several analytic epidemiological studies to iodine-131 (131I) thyroid doses received from the accident. However, there remains limited understanding of factors that modify the 131I-related risk. Focusing on post-Chernobyl pediatric thyroid cancer in Belarus, we reviewed evidence of the effects of radiation, thyroid screening, and iodine deficiency on regional differences in incidence rates of thyroid cancer. We also reviewed current evidence on content of nitrate in groundwater and thyroid cancer risk drawing attention to high levels of nitrates in open well water in several contaminated regions of Belarus, i.e. Gomel and Brest, related to the usage of nitrogen fertilizers. In this hypothesis generating study, based on ecological data and biological plausibility, we suggest that nitrate pollution may modify the radiation-related risk of thyroid cancer contributing to regional differences in rates of pediatric thyroid cancer in Belarus. Analytic epidemiological studies designed to evaluate joint effect of nitrate content in groundwater and radiation present a promising avenue of research and may provide useful insights into etiology of thyroid cancer.

In recent decades, differentiated thyroid cancer (DTC) incidence has been increasing worldwide. The important contributions to this phenomenon of “overdiagnosis” driven by wider use of improved ultrasound systems are amply documented, notwithstanding the “real” carcinogenic effects of ionizing radiation, e.g., from the Chernobyl accident or health care interventions. Less well understood is the role of nitrates – as environmental pollutants, in diet, and in medication – in thyroid carcinogenesis. Increasing exposure to nitrates is associated with rising incidence of esophageal, stomach, bladder, and colon cancers. Recent data suggest that in agricultural areas with higher mean nitrate levels in groundwater, DTC risk is also elevated. Our work in Belarus after Chernobyl has shown that children in districts with high nitrate concentrations in drinking water had significantly higher thyroid cancer incidence after irradiation than did their counterparts in areas with lower nitrate concentrations. Notwithstanding thyroid shielding, increasing use of computed tomography and dental X-rays heightens radiation exposure of the salivary glands in the general population, especially in children and adolescents. When nitrate intake is increased, salivary gland irradiation may potentially result in carcinogenic elevations in plasma nitric oxide concentrations. In conclusion, excess nitrate intake seems to be an independent risk factor for DTC. Additionally, we hypothesize from our data that high nitrate levels modulate the carcinogenic effect of radiation on the thyroid. Cohort studies, case-control studies, or both, are needed to quantify the effects of nitrates on DTC risk in the presence or absence of radiation exposure, e.g., that associated with diagnostic or therapeutic health care interventions.

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The rising incidence and optimization of management of nodular goiter and thyroid cancer are actual problems for many countries. In last decade radiofrequency ablation (RFA) is becoming more useful treatment option helping to avoid an overtreatment and surgical complications. This technique was developed in 2002 in South Korea and many European countries (Italy, Denmark, Spain, Germany, Austria) are offering RFA in special thyroid clinics. The first study of the effectiveness and feasibility of thyroid nodule RFA in the USA was conducted at Mayo Clinic in 2013, however number of patients and experience until now are very limited. Currently both monopolar and bipolar RFA techniques are used. To ablate small thyroid nodules (less than 2 cm in diameter), in 2017, in framework of american-belarusian clinical trial we started to use a new, originally developed, and patented, low-cost device for bipolar RFA - «Thyrablator». In comparison to a conventional monopolar electrode for RFA, Thyrablator, was designed as a sterile, disposable needle for the fine needle biopsy (20-gauge). It can be used with any type electrosurgical unit, operating in bipolar mode, attached to the generator with a removable connector and no need for a grounding pad. Thyrablator can also be used for drainage of cysts and for injection of liquids to enhance the ablative effect or for anesthetic instillation. Methodically ultrasound-guided percutaneous bipolar RFA was performed with local anesthesia, "moving-shot" technique, with the power of 3 to 5 Watt for duration of 30 to 60 seconds. It requires less time and power for successful ablation of nodes than stated in reports for monopolar electrode. An average reduction of nodule volume was approximately up to 60% after 3 months of follow-up. Conclusion. The first clinical trial showed a promising methodical approach of the new low-cost bipolar RFA device - Thyrablator. More studies are needed for active implementation bipolar RFA in clinical practice in the USA and training programs should begin preparing experienced interventional thyroidologists to treat patients, achieving good results and low complications rate. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.