Cancer incidence in Ukraine after the Chernobyl accident

Abstract

We analyzed the temporal trend in cancer incidence rate in different groups of Ukrainian population affected by the Chernobyl accident using the data obtained from the following two main information sources: (1) local cancer registry, which was established in 1987 and covers 150,000 population in the most radio-contaminated areas close to Chernobyl; and (2) state registry of people affected by the Chernobyl accident. The latter registry covers 90,000 emergency workers in 1986–1987 and 50,000 evacuees from Pripyat city and 30-km zone who received different doses of radiation. The mean dose was evaluated as 100–200 mSv for emergency workers in 1986, 50–100 mSv for those in 1987, and 10–12 and 20–30 mSv for evacuees from Pripyat city and 30-km zone, respectively. The lifetime dose in residents of contaminated areas with deposition density exceeding 555 kBq/m 2 was estimated to reach 100 mSv. A significant risk of thyroid cancer due to exposure to radioactive iodine was noted, especially in children. According to the evaluation of dose distribution in Ukrainian population, about 85% of children aged below 3 years received the dose of 0.1–1.0 Gy; 60% of children aged 4–15 years and 50% of adolescents received 0.05–0.3 Gy; and 15,000 children born on 1979–1986 before the accident received more than 2 Gy. Cancer incidence in people still living in contaminated areas has shown a slow increase with time more than 10 years after the accident. Comparison of the standardized incidence ratio (SIR) in the three groups of affected people, i.e., residents of contaminated areas, emergency workers in 1986–1987, and evacuees, the periods of 1990–1993 and 1994–1997 showed a significant increase in emergency workers in 1986–1987 only. As to site-specific cancer, a significant increase in thyroid cancer incidence in the three groups of population, especially in evacuees, should be noted. Breast cancer incidence rate showed a significant increase in female residents of contaminated areas and women who participated in emergency work in 1986–1987.