As show the results of years of research conducted in contingents exposed to prolonged high-ionizing radiation (such as nuclear bombing tests and disasters), the negative effect of irradiation is not confined to the direct effect on the treated. Nor is it possible to explain the peculiarities of morbidity in regions subjected to the effect of radioactive fallout by the presence of known hereditary (genetic) defects. There is a hypothesis that the increase in prevalence of several diseases in the descendants of exposed persons may be associated with poorly understood complex of minor genetic changes manifested at the level of regulatory systems dysfunction (nervous, endocrine and immune system, to a certain extent). One manifestation of this disregulatory complex may be the increased frequency of malignant tumors of hormone-dependent tissues in the descendants of exposed individuals. At the moment, there has been revealed a considerable number of genes that are predictors of various diseases, including cancer.
In terms of malignant neoplasms, modern epidemiological situation is characterized by reduction in the incidence of a number of previously highly-common tumors and increase of hormone-dependent tumors, especially those of female reproductive system organs. Breast cancer is in the first place in the structure of cancer incidence in women. Prognostically, breast cancer is favorable when it is timely detected. Unfortunately, in many cases there is a late detection of cancer associated with a greater risk of recurrence and metastasis after specific treatment. Several studies indicate the link between breast cancer and exposure to ionizing radiation. In particular, the increase in cancer incidence was detected in the areas of radiation risk at the Semipalatinsk Test Site (SNTS) that remains under the attention of researchers. There have also been identified peculiarities of genes-predictors prevalence associated with exposure to ionizing radiation, not only in directly exposed individuals, but also in their descendants.
Materials and methods: we studied the frequency of breast cancer in the region of the Semipalatinsk nuclear test site in view of the radiation risk zones in comparative perspective (for the period 1971–2011, according to data provided by the Department of Health of the former Semipalatinsk and Eastern Kazakhstan Province).
Research results: throughout the period analyzed, the incidence of breast cancer had a significant upward trend. The cumulative value increase from 1971 and 2006 amounted to 5 times (from 5,2 to 26,2 per 100,000 people a year). From 2006 to 2011, no significant changes in the incidence have been identified. Throughout the study, trend indicator was directed upward, indicating a continuing trend to its further increase.
There were significant differences in the radiation risk zones. The peculiarity of this indicator in the area of extraordinary radiation risk is a significant excess of its average value for the region and the republican average, existing throughout the whole period of study. A similar but less pronounced trend was found in the zone of maximum radiation risk.
The main feature of breast cancer incidence in the area of minimum radiation risk is its gradual growth, generally corresponding to the average national rate trends.
The work was submitted to International Scientific Conference «Development of scientific potential of higher education», UAE (Dubai), March, 4–11, 2014, came to the editorial office оn 11.02.2014.