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Background: Current knowledge about Chornobyl-related thyroid cancer risks comes from ecological studies based on grouped doses, case-control studies, and studies of prevalent cancers., Objective: To address this limitation, we evaluated the dose-response relationship for incident thyroid cancers using measurement-based individual iodine-131 (I-131) thyroid dose estimates in a prospective analytic cohort study., Methods: The cohort consists of individuals < 18 years of age on 26 April 1986 who resided in three contaminated oblasts (states) of Ukraine and underwent up to four thyroid screening examinations between 1998 and 2007 (n = 12,514). Thyroid doses of I-131 were estimated based on individual radioactivity measurements taken within 2 months after the accident, environmental transport models, and interview data. Excess radiation risks were estimated using Poisson regression models., Results: Sixty-five incident thyroid cancers were diagnosed during the second through fourth screenings and 73,004 person-years (PY) of observation. The dose-response relationship was consistent with linearity on relative and absolute scales, although the excess relative risk (ERR) model described data better than did the excess absolute risk (EAR) model. The ERR per gray was 1.91 [95% confidence interval (CI), 0.43-6.34], and the EAR per 10⁴ PY/Gy was 2.21 (95% CI, 0.04-5.78). The ERR per gray varied significantly by oblast of residence but not by time since exposure, use of iodine prophylaxis, iodine status, sex, age, or tumor size., Conclusions: I-131-related thyroid cancer risks persisted for two decades after exposure, with no evidence of decrease during the observation period. The radiation risks, although smaller, are compatible with those of retrospective and ecological post-Chornobyl studies.

The immunity changes were studied preoperatively in 36 patients suffering polynodose euthyroid goiter and in 85--postoperatively. The immunity system disorders are more profound in the early terms after the operation and their severity directly depends on its volume. The immunity changes are significantly expressed in adenomatous transformation of the thyroid gland tissues and in postoperative hypothyroidism.

The comparative analysis of immune state of the various age patients with benign and malignant thyroid gland (TG) tumors is presented. In the TG cancer the immunogenesis insufficiency is more pronounced. The data obtained trusts the perspectiveness of the immunocorrecting therapy application in patients with the TG cancer.

Levels of thymic hormones in blood serum were found to decrease during the development of Guerin's carcinoma, methylcholanthrene- and DMBA-induced carcinogenesis, soft tissue sarcomas, mammary cancer, in children with tumors of the urinary-genital tract, that evidences for the suppression of the thymic endocrine function in neoplastic processes. A decrease in the level of substances, active in the test under study is not revealed in patients with different forms of leukemias. The tumour elimination normalizes the thymic endocrine function, while multiagent chemotherapy increases the insufficiency. The data obtained suggest the immunotherapy for malignant neoplasms with thymic hormones.