Occup Environ Med 62:861-867 doi:10.1136/oem.2005.020826
  • Original article

Incidence of haematopoietic malignancies in US radiologic technologists

  1. M S Linet1,
  2. D M Freedman1,
  3. A K Mohan2,
  4. M M Doody1,
  5. E Ron1,
  6. K Mabuchi1,
  7. B H Alexander3,
  8. A Sigurdson1,
  9. M Hauptmann1
  1. 1Division of Cancer Epidemiology and Genetics, National Cancer Institute, Department of Health and Human Services, Bethesda, MD, USA
  2. 2Office of Biostatistics and Epidemiology, Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD, USA
  3. 3Division of Occupational and Environmental Health, University of Minnesota, Minneapolis, MN, USA
  1. Correspondence to:
 Dr M S Linet
 Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 6120 Executive Blvd. EPS Room 7054, Bethesda, Maryland 20892, USA;
  • Accepted 19 May 2005


Background: There are limited data on risks of haematopoietic malignancies associated with protracted low-to-moderate dose radiation.

Aims: To contribute the first incidence risk estimates for haematopoietic malignancies in relation to work history, procedures, practices, and protective measures in a large population of mostly female medical radiation workers.

Methods: The investigators followed up 71 894 (77.9% female) US radiologic technologists, first certified during 1926–80, from completion of a baseline questionnaire (1983–89) to return of a second questionnaire (1994–98), diagnosis of a first cancer, death, or 31 August 1998 (731 306 person-years), whichever occurred first. Cox proportional hazards regression was used to compute risks.

Results: Relative risks (RR) for leukaemias other than chronic lymphocytic leukaemia (non-CLL, 41 cases) were increased among technologists working five or more years before 1950 (RR = 6.6, 95% CI 1.0 to 41.9, based on seven cases) or holding patients 50 or more times for x ray examination (RR = 2.6, 95% CI 1.3 to 5.4). Risks of non-CLL leukaemias were not significantly related to the number of years subjects worked in more recent periods, the year or age first worked, the total years worked, specific procedures or equipment used, or personal radiotherapy. Working as a radiologic technologist was not significantly linked with risk of multiple myeloma (28 cases), non-Hodgkin’s lymphoma (118 cases), Hodgkin’s lymphoma (31 cases), or chronic lymphocytic leukaemia (23 cases).

Conclusion: Similar to results for single acute dose and fractionated high dose radiation exposures, there was increased risk for non-CLL leukaemias decades after initial protracted radiation exposure that likely cumulated to low-to-moderate doses.


  • Funding: National Cancer Institute, National Institutes of Health, Department of Health and Human Services; contract numbers NO1-CP-51016, NO2-CP-81121, NO2-CP-81005

  • Competing interests: none declared