PCP: Medical radiation ups breast cancer risk
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The President's Cancer Panel released this week an annual report on the cancer risks from the environment warning that medical radiation raises breast cancer risk.
The PCP says that substantial evidence exists that medical radiation, which is used to diagnose and treat cancer among other things, is an important and controllable cause of breast cancer.
Dr. John Gofman, a distinguished nuclear physician, Ph.D. and M.D., suggested that medical radiation is implicated in 75 percent of breast cancer cases.
He said in his 1996 book titled "Preventing Breast cancer" each mammogram examination requires two views of each breast and each view needs 0.1 rad of x-ray. That means each breast will receive 0.2 rad.
He calculated the risk and found that of women aged 30 to 34 who receive five exams, about 5 out of 1000 will acquire radiation-induced breast cancer. Of women aged 35 to 49 who receive 10 exams, slightly more than 5 out of 1000 will get radiation-induced breast cancer. Of women aged 50 to 64 who get 15 exams, about 8 out of 1000 will develop radiation-induced breast cancer.
Regulations permit the dose per exam to be three times higher (up to 0.6 rad), which means the potential risk in some women can also be three times higher. False positives will lead to more radiation based exams, further raising the risk.
Dr. Golfman acknowledged that not every woman who gets mammogram screening will get radiation-induced breast cancer, but some definitely will. The worse thing is that no one knows who will and who won't get breast cancer induced by x-rays used in medical diagnostic tools like mammography.
Ionizing radiation, the commonly form used in medical diagnosis and treatment, is x-ray. The National Toxicology Program has recognized radiation is a human carcinogen.
In the annual report for 2008-2009, the PCP says "minimizing radiation dose to breast tissue is critically important, particularly in girls and young women."
It suggests that by all means, patients should avoid a chest CT, which delivers an organ dose to the breast equal to about 15 sets of mammograms. Mammograms are also linked to increased risk of breast cancer, according to previous studies.
One chest CT can deliver 10 to 80 mGy of radiation while a single mammogram gives less than 3 mGY.
The report does not quantify the risk from radiation. It says children are more vulnerable to the damage and doctors should consider a patient's history of exposure to radiation because the damage from radiation is cumulative.
Dr. Gofman said there is no absolute safe threshold, meaning any dose increases the cancer risk.
The President's Cancer Panel included Lasalle D. Leffall, Jr. M.D. from Howard University College of Medicine in Washington DC and Margaret L. Kripke, Ph.D. from the University of Texas M.D. Anderson Cancer Center in Houston, Texas.
For more information on the report, read
Annual Report for 2008-2009
Reducing Environmental Cancer Risk, What We Can Do Now
Reducing Environmental Cancer Risk, What We Can Do Now
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