Balancing the benefits and harms of thyroid cancer surveillance in survivors of Childhood, adolescent and young adult cancer: Recommendations from the international Late Effects of Childhood Cancer Guideline Harmonization Group in collaboration with the PanCareSurFup Consortium.

Radiation exposure to the thyroid gland during treatment of childhood, adolescent and young adult cancer (CAYAC) may cause differentiated thyroid cancer (DTC). Surveillance recommendations for DTC vary considerably, causing uncertainty about optimum screening practices. The International Late Effects of Childhood Cancer Guideline Harmonization Group, in collaboration with the PanCareSurFup Consortium, developed consensus recommendations for thyroid cancer surveillance in CAYAC survivors. These recommendations were developed by an international multidisciplinary panel that included 33 experts in relevant medical specialties who used a consistent and transparent process. Recommendations were graded according to the strength of underlying evidence and potential benefit gained by early detection and appropriate management. Of the two available surveillance strategies, thyroid ultrasound and neck palpation, neither was shown to be superior. Consequently, a decision aid was formulated to guide the health care provider in counseling the survivor. The recommendations highlight the need for shared decision making regarding whether to undergo surveillance for DTC and in the choice of surveillance modality.

Experience of thyroid gland status screening in postchernobyl period.

The main results of thirty-year period of repeated screening programs and observational studies in contaminated and non-contaminated regions of Belarus are analyzed. The possible reasons of discrepant and contradictory data about the consequences of Chernobyl catastrophe delivered by different study groups during early period after the accident are discussed. High incidence of thyroid nodular disease and cancer in children and adolescence after the catastrophe are described. The research shows high effectiveness of screening in early diagnosis thyroid disorders and radiation-induced thyroid cancer in different regions of Belarus and in various time points.

Influence of nitrate in drinking water on the prevalence of thyroid cancer and other diseases (literature review and experience in post-chernobyl period in Belarus).

In the last 60 years dramatically increased the content of nitrates in groundwater due to intensive use of nitrogen fertilizers in agriculture. Research in post-Chernobyl period has shown that a sharp increase in the incidence of thyroid cancer depends not only on the level of thyroid dose, but also on the level of nitrates in groundwater.

Thyroid cancer in infants and adolescents after Chernobyl.

Studies in children medically exposed to external irradiation more than 50 years ago revealed a considerably increased risk for thyroid cancer. Similarly, a strongly age-dependent risk for thyroid cancer was observed in the Japanese population after the atomic bomb explosions with the highest risk in the group of children below age of 10. After the Chernobyl accident, children from Belarus living in highly exposed regions received mean thyroid doses by radioactive fallout higher by a factor of approximately 2 as compared to the survivors of the atomic bomb explosions. This lead to a radiation related increase of thyroid cancer incidence in children and adolescents with the highest incidence in age group 0-4 years up to now totally amounting to approximately 5 000 cases. For screening of thyroid cancer in children, high resolution ultrasound is the method of choice which has to be complemented by fine-needle aspiration biopsy in suspicious cases. Diagnostic criteria for malignancy in childhood thyroid cancer by ultrasound are hypoechogenicity and irregularity of the outline, subcapsular location of lesions and increased peri-intranodular vascularisation. The treatment strategy for thyroid cancer in children does not differ substantially from the approach used in adults. Primary treatment consists of thyroidectomy and lymph node dissection. Careful and complete removal of the lymph nodes is of great clinical relevance in children because of very frequent node involvement (between 40% and 90%). Because of the high prevalence of lymph node metastases, ablation of thyroid remnants is mostly indicated in children with thyroid cancer. Distant metastases which need higher activities of radioiodine are less frequent with 10-20%. Even in advanced cases of childhood thyroid cancer, long-lasting remissions can be achieved. A specific finding in children is disseminated, milliary lung metastases with intense radioiodine uptake. In this situation, pulmonary fibrosis may be a severe side-effect so that the indication for repeated courses of radioiodine therapy has to be decided thoroughly. With respect to side-effects of radioiodine therapy, the risk of developing breast cancer has to be taken into account seriously since especially the female breast is exposed to a relatively high radiation dose. Generally, young patients treated with high activities of radioiodine should be carefully followed up during their whole lifespan.

Impact of parathyroid status and Ca and vitamin-D supplementation on bone mass and muscle-bone relationships in 208 Belarussian children after thyroidectomy because of thyroid carcinoma.

This observational study analyzes Ca-P metabolism and its impact on bone mass accrual and density and the muscle-bone mass/mass relationships in male and female children and adolescents who were parathyroidectomized because of thyroid carcinoma. Two hundred and eight children and adolescents (119 girls and 89 boys) from Gomel city (Belarus) and its rural surroundings were referred to our institution after having undergone total thyroidectomy for the treatment of advanced papillary thyroid cancer. A subgroup of children with demonstrated primary hypoparathyroidism received dihydrotachysterol (AT-10) and/or Ca supplementation. Among routine procedures over a maximum follow-up period of 5 years (average 3.7 years, maximum 8 visits), whole-body scans were taken using dual energy X-ray absorptiometry (DXA) at each visit in order to determine whole-body bone mineral content (TBMC), projected "areal" bone mineral density (TBMD), total lean mass (TLM) and total fat mass (TFM). The average serum Ca, P and AP concentrations over the whole observation period were significantly different between the groups; however, TBMC z-scores for all studied children were statistically similar in all visits. In girls, no between-group differences in height- and weight-controlled TBMC and TBMD or the TBMC/TLM ratio were observed (ANCOVA) and supplementation exerted no effect on these data, suggesting that the total bone mass accrual was not impaired by PTH deficiency in the studied conditions. However, non-supplemented boys showed lower values of the TBMC/TLM ratio than girls, and supplementation normalized these values in direct correlation with the induced improvement in serum P availability to bone. Results indicate that the primary impairment in parathyroid function and bone metabolism indicators in the thyroidectomized children was unrelated to any measurable change in crude bone mass values. However, in boys this condition impaired the TBMC/TLM ratio in such a way that the administered supplementation could normalize it as a function of improved P availability. Girls' skeleton seemed to have been naturally protected against the negative metabolic effect of the studied condition. An estrogen-induced enhancement of the biomechanical impact of muscle contractions on bone mass and structure could not be excluded in this group.

Characteristics of thyroid ultrasound pictures in children with nodular thyroid changes effected by radionuclides.

97 children with thyroid nodules found through screening programs in regions of White Russia (Belarus) affected by fallout from the Chernobyl disaster underwent thyroid ultrasound examination by one team at a central reference hospital. 46 of these children were operated on. 31 of these had thyroid carcinoma (30 papillary carcinoma, 1 follicular carcinoma), 9 adenoma, 3 nodular goitre, 2 thyroiditis and one colloid goitre. Sex distribution was equal in the carcinoma group while in all other groups females prevailed. In younger age groups (3-6 and 7-10 years) carcinomas were found more often than adenomas and cysts. A carcinoma was present most likely if there were a single nodule with a volume of more than 1.5 cm3, inhomogeneous echo structure, unclear, hypoechogenic margins, and enlarged regional lymph nodes.