Scientific Protocol for the Study of Leukemia and Other Hematologic Diseases Among Clean-up Workers in Ukraine Following the Chernobyl Accident

February 19, 2020 updated by: National Cancer Institute (NCI)

Leukemia holds a special place in the study of radiation-related cancer because bone marrow is one of the tissues most sensitive to the carcinogenic effect of ionizing radiation, radiogenic leukemia has the shortest latent period among radiation-induced cancers, and its appearance suggests that solid tumors may follow. These same characteristics also contribute to its considerable significance in radiation protection. There are, nevertheless, important gaps in existing knowledge of radiation-induced leukemia, gaps that derive from characteristics of the study of the atomic bombing of Hiroshima and Nagasaki, and from studies of the effects of medical irradiation and studies of nuclear workers, these being the studies that have provided most of the information to date. These gaps include the presumed reduction in risk resulting from dose-fractionation and low dose-rate, and the time-response function in the first five years after exposure.

The primary objective of this study is to investigate leukemia risk as a function of such radiation; it would constitute the largest epidemiologic study conducted to date among working-age males, a group of particular concern in establishing occupational radiation safety standards. In addition, data on cases of multiple myeloma and myelodysplasia identified in the cohort will be collected to test the hypothesis of a dose related association between radiation and increased risk for each of these diseases.

The primary scientific objectives of the proposed study are to test the following hypotheses: (a) that there is a dose-related increase in risk of leukemia among these liquidators; (b) that the magnitude of any observed risk per unit dose is less than that seen in the atomic bomb survivors, exposed to essentially instantaneous radiation.

Subsidiary objectives include: (a) to investigate the nature of the dose-response relationship among liquidators and to identify modifiers of risk, including time since exposure, age at exposure, etc.; (b) to test the hypothesis that there is a dose-related increased risk of multiple myeloma; (c) to test the hypothesis that there is a dose-related increased risk of myelodysplasial; (d) to collect and store buccal cells from about 2,000 liquidators with a wide range of dose estimates extending to well over 1 Gy for possible use in future molecular studies of their DNA.

Study Overview

Status

Completed

Conditions

Detailed Description

Leukemia holds a special place in the study of radiation-related cancer because bone marrow is one of the tissues most sensitive to the carcinogenic effect of ionizing radiation. Radiogenic leukemia has the shortest latent period among radiation-induced cancers, and its appearance suggests that solid tumors may follow. These same characteristics also contribute to its considerable significance in radiation protection. There are, nevertheless, important gaps in existing knowledge of radiation-induced leukemia, gaps that derive from characteristics of the study of the atomic bombing of Hiroshima and Nagasaki, and from studies of the effects of medical irradiation and studies of nuclear workers; these are the studies that have provided most of the information to date. The gaps include the presumed reduction in risk resulting from dose-fractionation and low dose-rate, as well as the time- response function in the first five years after exposure. The study described herein is intended to fill those gaps.

The Chornobyl accident exposed hundreds of thousands of people to radiation, notably those involved in its cleanup operations. The second phase of a case-control study of ionizing radiation and leukemia is being conducted in a cohort of approximately 100,000 Ukrainian "liquidators" involved in cleanup work following the accident at the Chornobyl Nuclear Power Plant in northern Ukraine which occurred on April 26, 1986. The cohort is restricted to liquidators who first worked around the power plant between 1986 and 1990 and were residents, when first registered in the Chornobyl State Registry, in Kyiv City or in one of five oblasts (major civil divisions) that comprise the study area. This cohort, consisting of males of working age, received mean bone marrow doses of approximately 80-100 milli-gray (mGy) at low to moderate dose rates, with those sent earlier receiving the highest doses. The primary objective of this study is to investigate leukemia risk as a function of such radiation; it constitutes probably the largest epidemiologic study conducted to date among working-age males, a group of particular concern in establishing occupational radiation safety standards.

The primary scientific objectives of the proposed study are to evaluate whether there is a doserelated increase in risk of leukemia among these liquidators, and how it compares with the observed risk per unit dose seen in the atomic bomb survivors, exposed to essentially instantaneous radiation. A secondary objective is to identify any modifiers of risk, including time since exposure, age at exposure, etc.

The field work for the second phase of the study, with an extended case ascertainment for 2001 through 2006 has been complated. As a result of the second phase, a total of75 confirmed cases of leukemia and 12 cases of multiple myeloma have been ascertained. We are currently in the process of database construction, dosimetric calculation for data analyses for leukemia, and manuscript preparation.

The small sub-study on uncertainties associated with human factors is to be started upon SSIRB approval.

Study Type

Observational

Enrollment (Actual)

1779

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Ukraine
      • Kiev, Ukraine
        • Research Center for Radiation Medicine

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 70 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Probability Sample

Study Population

Ukrainian Chernobyl cleanup workers ("liquidators") approx. 100,000 persons

Description

  • INCLUSION CRITERIA:

We intend to include in the proposed study all 350 clean-up workers with "historical" records and 150 proxies to be identified by the liquidators; however, we anticipate a considerable number of them will not be available for the study due to deaths, not being able to be traced, no response, refusals, etc. The study subjects will be interviewed in person. All study subjects are males, median age of early liquidators is 64 y while for clean-up workers sent to mission is about 61 years.

EXCLUSION CRITERIA:

Excluded from the study will be those who have been found to be deceased, cannot be located, refuse to participate in the study, or do not provide informed consent.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Cohort of Chernobyl cleanup workers (liquidators) in Ukraine
Cases with leukemia and related diseases, and matched controls in the cohort

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The primary objective of this study is to investigate leukemia risk as a function of radiation ionizing radiation from occupational exposure (Chernobyl nuclear power plant)
Time Frame: time of interview
Estimated risk of leukemia related to radiation exposure
time of interview

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Cancer Institute (NCI)

Investigators

  • Principal Investigator: Kiyohiko Mabuchi, M.D., National Cancer Institute (NCI)

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 26, 1996

Primary Completion (Actual)

February 12, 2020

Study Completion (Actual)

February 12, 2020

Study Registration Dates

First Submitted

June 19, 2006

First Submitted That Met QC Criteria

June 19, 2006

First Posted (Estimate)

June 21, 2006

Study Record Updates

Last Update Posted (Actual)

February 21, 2020

Last Update Submitted That Met QC Criteria

February 19, 2020

Last Verified

February 1, 2020

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 999996030
  • OH96-C-N030

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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