Cancer incidence among nuclear workers in Russia based on data from the Institute of Physics and Power Engineering: a preliminary analysis

One group that has the potential to be exposed to radiation is workers in the nuclear industry. Results of a systematic medical follow-up and dosimetric monitoring of these workers can form the basis for a study of the relationship between cancer incidence and radiation dose. As part of such efforts in Russia, a major institution of the nuclear industry with an established medical care unit, archiving capabilities, and dosimetry department was selected: the Institute of Physics and Power Engineering (IPPE) in Obninsk. In the study, a comparative analysis of cancer incidence rates for the IPPE workers and for the general population of Russia in 1991-1997 was carried out. The subjects were the IPPE workers hired before 1981. This restriction was imposed to reduce the uncertainty associated with the possible latent period in the development of solid cancers. Thus the possibility of including persons who already had the disease at the time when they were hired was minimized. The analysis is based on information about 158 cancer cases, including 24 cancers in persons under individual dosimetric monitoring. A statistically significant excess in cancer incidence was found among the IPPE workers compared with a comparison population (the general population of Russia) for some types of cancers. The SIR values for all cancers (ICD-9: 140-208) is 0.93 (95% CI 0.76, 1.12) for males and 1.42 (95% CI 1.06, 1.87) for females. A statistically significant excess for all cancers was also observed for residents of Obninsk compared to the control comparison population. The corresponding SIR value was 1.20 (95% CI 1.12, 1.28) for males and 1.58 (95% CI 1.49, 1.69) for females. An important reason for the observed excess in cancer incidence compared to the control population may be the higher level of health care in the so-called nuclear cities of Russia which may have resulted in increased diagnosis and registration of cancers. A statistically significant dependence of the cancer incidence on the dose of ionizing radiation was not established. The excess relative risk per gray for all types of cancer was 0.91 (95% CI -2.75, 4.61) for males and 0.40 (95% CI -6.94, 7.83) for females. These estimates should be considered to be preliminary, as the number of cases considered in the analysis of the dose response is small (17 males and 7 females).