Female X-ray techs exposed to smaller doses of radiation, study shows

[Susan L Gawarecki <loc@icx.net>]

Has anyone seen this study?  The article raises a lot of questions in my

mind (not to mention a headline that doesn't make much sense relative to

the article).



1. Were death rates or incidence rates used as a basis for comparison? 

If the first, it should be noted that current treatments are more likely

to cure breast cancer than the treatments of yesteryear.



2. Were the death/incidence rates age adjusted?  If not, then many of

the technicians exposed at today's lower rates have not yet reached the

age at which they are more likely to develop breast cancer

(post-menopause).



A recently released study implicating cigarette smoking as to causing

more types of cancers than previously known notes that rates of the

hormonally mediated cancers in women are not affected, i.e. smoking does

not increase the risk of breast cancer or ovarian cancer.  This also

raises questions about how much additional risk radiation causes in such

cancers.



Any info on the design of this study would be welcome.



--Susan Gawarecki



Female X-ray techs exposed to smaller doses of radiation, study shows

By PAUL RECER, AP Science Writer 



WASHINGTON (June 19, 2002 6:30 a.m. EDT) - Female X-ray technicians

today have a smaller risk of breast cancer than those who started work

when radiation exposure limits were much higher, a study shows. 



Researchers analyzed the health histories of 69,525 women who worked as

X-ray technicians during the years 1926 through 1982 and found that

breast cancer deaths were more common during the early years. 



A report on the study appears Wednesday in the Journal of the National

Cancer Institute. 



After adjusting for other health factors, such as a family history of

breast cancer, the authors found that women who worked as X-ray

technicians before 1940 were nearly three times more likely to die of

breast cancer than those first employed in 1960 or later. 



For those working between 1940 and 1949, the risk of death from breast

cancer was 2.5 times greater than those who started work after 1960. 



"Our findings - that breast cancer mortality was highest among

technologists who first worked in the earlier calendar periods -

probably reflects changing exposures to radiation over time," the

authors said. 



Before 1934, the recommended exposure limit for medical radiation

workers was 70 REMs a year. The recommended exposure limit was steadily

reduced over the years and was set in 1958 at five REMs a year. A REM,

for roentgen equivalent man, is a measure of absorbed ionizing radiation

doses. 



"The high risks of breast cancer mortality for women exposed to

occupational radiation prior to 1950 and the subsequent decline in risk

are consistent with the dramatic reduction in recommended radiation

exposure limits over time," the authors said. 



The study was compiled by 11 researchers representing the National

Cancer Institute, the Food and Drug Administration, the University of

Minnesota, Vanderbilt University Medical Center and Johns Hopkins

Bloomberg School of Public Health.

--

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