Radiation May Increase Increased Breast Cancer Risks

Breast cancer risks may jump in BRCA carriers who have had chest radiation before 30

/ Author:  / Reviewed by: Chris Galloway, M.D.

(RxWiki News) Women who inherited one of the BRCA genes already have an increased risk of developing breast cancer. Certain medical tests – performed at certain ages – may increase those increased risks.

Women with altered BRCA1 or BRCA2 genes may be at even greater risk of developing breast cancer if they’ve had a chest x-ray or mammogram before the age of 30.

They may be more likely to develop the disease than BRCA carriers who haven’t had these tests.

This study, while interesting, has to be viewed with caution, because not many women in the study had received a mammogram before the age of 30.

"If cancer runs in your family, talk to your doctor about genetic testing."

Authors in the Netherlands uncovered this possible association after surveying nearly 2,000 women in Holland, France and the UK between 2006-2009.

BRCA genes help repair DNA damage to protect against breast and ovarian cancer. So women who have mutations in these genes are more likely to develop these cancers than women without the altered genes.

These genes are thought to be especially sensitive to radiation, which itself can be a risk factor for breast cancer in young women. So undergoing mammography to detect breast cancer in BRCA carriers under the age of 30 may be more harmful than beneficial, the authors suggest.

dailyRx News reached out to Daniel J Kopans, MD, professor of radiology at Harvard Medical School and senior radiologist of the Breast Imaging Division at Massachusetts General Hospital.

"It is important for women to realize that only 10 percent of women diagnosed with breast cancer each year are genetically predisposed, and approximately 2 percent of women have these DNA mutations, so that this analysis does not apply to 98 percent of women," said Dr. Kopans, who was not involved with the study.

He goes on to explain that BRCA carriers "are at a huge increased risk for developing breast cancer early in life just based on their genetics. The question is might mammography screening in their twenties save their lives?

"This paper simply restates, but does not add to what everyone has wondered – Does the benefit of early detection for these very high risk women outweigh the theoretical, but still unproven, risk from the radiation," Dr. Kopans told dailyRx News.

"If anything, this paper suggests that the risk is not high enough for them to have demonstrated it, which is good news to continue with mammography alternating with MRI screening as we recommend in the US for these women," he said.

For the study, women were asked how old they were when they received their first chest x-ray or mammogram. The study participants reported how many times they’d been exposed to radiation before the age of 20, between the ages of 20-29, 30-39 and their age at last exposure.

Here’s what the researchers learned:

  • 43 percent of the women had been diagnosed with breast cancer.
  • 48 percent reported having had an x-ray; 33 percent said they’d had a mammogram.
  • 29 was the average age of the first mammogram.
  • Any radiation exposure to the chest increased breast cancer risk by 43 percent.
  • Exposure before the age of 20, increased the risk by 62 percent.
  • Radiation exposure between 30-39 didn’t appear to influence cancer risks.

So to put this into perspective, let’s look at the actual numbers. According to this study, 9 out of every 100 women with BRCA1 or 2 mutations aged 30 will have breast cancer by the time they are 40.

If all of these women had a mammogram before the age of 30, the number of breast cancer cases would increase from 9 to 14 out of every 100 BRCA1 or 2 carriers.

Researchers conclude that different types of imaging studies may be best for BRCA carriers, including MRI (magnetic resonance imaging).

Dr. Kopans agrees. "We don't know if MRI is sufficient, but certainly for women in their twenties, who have genetic mutation, it is not unreasonable to screen with MRI and then alternate with mammography when they get into their thirties," Dr. Kopans said.

Mammograms typically range in cost between $150-275. A breast MRI scan costs about $1,300.

One of the “puzzling” findings in the study, according to the authors, was the difference in cancer risks between women with BRCA1 and those with BRCA2 genes.

The researchers say that additional study is needed to confirm this difference.

This study was published September 9 on www.bmj.com, the website of the British Medical Journal.

The study was supported by Euratom Programme; GENEPSO: Fondation de France and Ligue National Contre le Cancer; EMBRACE: Cancer Research UK; HEBON: Dutch Cancer Society.

Several of the authors disclosed potential conflicts of interest.

Reviewed by: 
Review Date: 
September 10, 2012
Last Updated:
November 16, 2012