[ RadSafe ] News: Chest x-ray may increase likelihood of breast cancer

John Jacobus crispy_bird at yahoo.com
Mon Aug 7 08:18:05 CDT 2006

Posted at

Of course, we are dealing with a subpopulation with
the BRCA1 and BRACA2 genes.
Diagnostic Imaging Online
August 2, 2006
Chest x-ray may increase likelihood of breast cancer

An analysis of 1600 women with BRCA1 and BRCA2
mutations suggests that exposure to chest x-rays may
increase the risk of breast cancer. Exposure before
the age of 20 may be linked to particularly heightened

The research, conducted by a consortium of European
cancer centers, was the first to analyze the impact of
low-level x-ray exposure among women at genetically
high risk for the disease. The study was published
online June 26 in the Journal of Clinical Oncology. 

"This is one of the first studies to demonstrate that
women genetically predisposed to breast cancer may be
more susceptible to low-dose ionizing radiation than
other women," said lead author David E. Goldgar,
Ph.D., chief of the genetic epidemiology group at the
International Agency for Research on Cancer in Lyon,
France, at the time the research was conducted. 

If findings are confirmed in prospective studies,
young women in families known to have BRCA1 or BRCA2
mutations may wish to consider alternatives to x-ray,
such as MRI, Goldgar said. 

Researchers analyzed questionnaire data completed by
more than 1600 women who were involved in the
International BRCA 1/2 Carrier Cohort Study (IBCCS), a
collaborative European study of women who carry
BRCA1/2 mutations. While all the women were carriers,
not all had developed breast cancer. 

The questionnaire asked whether a woman had ever
received a chest x-ray, whether she had received chest
x-rays before age 20, after age 20, or during both
periods, and how many x-rays she had been exposed to
during each time frame. 

The study found that women with BRCA1/2 mutations who
reported ever having a chest x-ray were 54% more
likely to develop breast cancer than women who had
never undergone the procedure. Women who were exposed
to x-rays before age 20 had a 2.5-fold increased risk
of developing the disease before age 40, compared with
women who had never been exposed. 

"Since BRCA proteins are integral in repairing damage
to breast cells, we hypothesized that women with
BRCA1/2 mutations would be less able to repair damage
caused to DNA by ionizing radiation," Goldgar said.
"Our findings support this hypothesis and stress the
need for prospective studies." 

Investigators noted two primary limitations of the
study. The first was the potential for recall bias,
meaning that women who had developed breast cancer
might be more likely to remember receiving an x-ray
than women who had not been diagnosed with the
disease. The second was lack of data on the specific
dose and timing of radiation that was received. 

-- By By Danielle Potuto 

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>From an article about physicians doing clinical studies: 

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Statistician: "Oh, so you have already calculated the P value?"

Surgeon: "Yes, I used multinomial logistic regression."

Statistician: "Really? How did you come up with that?"

Surgeon: "Well, I tried each analysis on the SPSS drop-down menus, and that was the one that gave the smallest P value"."

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com

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