Abstract
Over 400 nuclear tests were carried out at Semipalatinsk Nuclear Test Site (SNTS) of Kazakhstan from 1949 to 1989. According to the statistics at Oncology Center in Semipalatinsk the number of breast cancer incidence increased from 15.7% in 2003 to 24.9% in 2004. The objective of this study was to elucidate the risk of breast cancer by radiation exposure caused by a series of nuclear weapon tests at SNTS. The study subjects were women born from 1935 to 1962 and were living in the areas adjacent to the SNTS, i.e. Semipalatinsk city, and districts of Abay, Zhana-Semey, Beskaragay and Boroduliha of the East Kazakhstan region. The information on cases with primary breast cancer diagnosed in 1980-2005 was obtained through cancer registry at Oncology Centre in Semipalatinsk. Two age-matched controls were selected for each case in the above-mentioned areas. We developed a questionnaire including items of residential history and other risk factors, and made face to face interview in the summer of 2005 after obtaining the informed consent from the participants. A total of 85 cases and 163 controls from 24 villages in East-Kazakhstan region were enrolled into this study. A statistically significant difference between cases and controls was observed in alcohol consumption (p=0.01), while a marginally significant difference was observed in abortion (p=0.07) and miscarriage (p=0.08). The findings could serve as moderate modifiers for other risk factors including ionizing radiation. The study on the association between radiation exposure and breast cancer is underway.
