Solid cancer incidence other than lung, liver and bone in Mayak workers: 1948-2004

Background: Cancer incidence in the Mayak Production Association (PA) cohort was analysed to investigate for the first time whether external gamma-ray and internal plutonium exposure are associated with raised incidence of solid cancers other than lung, liver and bone (other solid cancers). Methods: The cohort includes 22 366 workers of both sexes who were first employed between 1948 and 1982. A total of 1447 cases of other solid cancers were registered in the follow-up period until 2004. The Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to plutonium and external gamma-ray. Results: A weak association was found between cumulative exposure to external gamma-ray and the incidence of other solid cancers (ERR/Gy = 0.07; 95% confidence intervals (CIs): 0.01-0.15), but this association lost its significance after adjusting for internal plutonium exposure. There was no indication of any association with plutonium exposure for other solid cancers. Among 16 individual cancer sites, there was a statistically significant association with external exposure for lip cancer (ERR/Gy = 1.74; 95% CI: 0.37; 6.71) and with plutonium exposure for pancreatic cancer (ERR/Gy = 1.58; 95% CI; 0.17; 4.77). Conclusion: This study of Mayak workers does not provide evidence of an increased risk of other solid cancers. The observed increase in the risk of cancer of the lip and pancreas should be treated with caution because of the limited amount of relevant data and because the observations may be simply due to chance.