This is regarding the Tribune article “Mammograms seen as risky for some; Study says X-rays may be harmful for women with genetic flaw tied to breast cancer” (News, June 27).
The report, by Tribune staff reporter Judy Peres, that some women with BRCA1 and BRCA2 gene mutations have an increased risk for breast cancer if they have also had at least one chest X-ray, should come as no surprise since it is known that ionizing radiation, such as X-rays, damages DNA and can cause genetic mutations predisposing to cancer.
The article speculates that mammography may also increase the risk of breast cancer in genetically susceptible women.
There has been controversy about the benefits of yearly mammography in reducing deaths from breast cancer.
The apparent benefit of early diagnosis is relatively small.
One possible reason is that the cumulative radiation dose from years of mammography examinations may actually induce cancer at a rate that, on balance, subtracts from the number of lives saved by early diagnosis.
The most prominent mutagenic agents in our environment are natural background radiation and medical X-rays. If a de novo mutation from X-ray exposure affects genes that control DNA repair mechanisms (such as BRCA1 and BRCA2), or other genes controlling cell multiplication and turnover, then cancer can arise even in the absence of a family history or a pre-existing genetic susceptibility.
Although mammography is said to deliver a relatively low dose of radiation, the cumulative dose over decades becomes significant.
Moreover ionizing radiation is a no-threshold biologic phenomenon.
There is no such thing as a safe dose below which DNA damage is negligible.
