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NCI News Note

Increased risk of chronic lymphocytic leukemia in Chernobyl cleanup workers

  • Posted: November 8, 2012

A new study found a significantly elevated risk for chronic lymphocytic leukemia among workers who were engaged in recovery and clean-up activities following the Chernobyl power plant accident in 1986. Radiation has been long known to increase the risk of various types of leukemia. Earlier studies of Chernobyl cleanup workers suggested there might be an increased risk of chronic lymphocytic leukemia (a less aggressive form of leukemia) associated with radiation exposure, and this new study provided stronger evidence to support this association. The researchers estimated that 16 percent of all leukemia cases in the worker population (15 percent for non-chronic lymphocytic leukemia and 18 percent for chronic lymphocytic leukemia), over a period of 20 years of medical follow-up, were attributable to radiation exposure from the nuclear reactor accident. This international study was conducted by NCI, Columbia University, New York, the University of California San Francisco (UCSF), and the Research Center for Radiation Medicine in Kiev, Ukraine, and appeared online November 8, 2012, in Environmental Health Perspectives.

The investigators, led by Lydia Zablotska, M.D., Ph.D., UCSF, followed 110,000 Ukrainian workers who participated in the cleanup following the Chernobyl accident.  New cases of leukemia were tracked from 1986 through 2006, and were confirmed by a panel of expert hematologists. Researchers estimated the individual radiation doses to the bone marrow for the leukemia patients and a comparison group similar to the patients in age and place of residence. Findings showed that exposure to radiation from post-Chernobyl cleanup work resulted in an increased risk of chronic lymphocytic leukemia as well as other types of leukemia known to be linked to radiation exposure.  The authors of the study urge further research into the association between radiation and chronic lymphocytic leukemia which is the most common type of leukemia in older people in Western populations. Knowledge of this risk factor opens up avenues for novel research into the biological mechanisms responsible for CLL.