Neil Hall: Just more mammography confusion

March 6, 2014 

Regarding the Feb. 27 Point of View “Clarity, not confusion” on mammograms: The writer clearly expressed the opinion of radiologists, who benefit financially from patients having mammograms, but provided no balancing views widely accepted by national authorities.

First, with regards to the improvement in screening with digital mammography in order to get a “clear and accurate diagnosis of breast cancer,” UpToDate, an outstanding medical reference for physicians, says several studies have found little difference in cancer detection rates between digital and film mammography. And that, “Digital mammography ... in women younger than 50 ... is also associated with an increased rate of false-positive findings in this population.”

False positives can cause emotional distress, repeated mammograms and biopsies or surgeries, including mastectomies for benign disease. That is one of the reasons national experts are questioning mammography.

Second, the contribution of mammograms to improved survival is debatable. Recent advances in treatment have markedly improved survival, even in women with advanced breast cancers. One recent study of mammogram effectiveness suggested that only 8 to 10 percent of the reduction in deaths was due to mammograms, the rest caused by effective treatment. Previously, mammograms were recommended annually, as the writer recommends. But multiple studies have shown that for persons over age 50, mammograms every two years save just as many lives as yearly mammograms.

The writer cites the recommendations of four organizations, but the recommendation of the most authoritative and unbiased group was ignored. The U.S. Preventive Services Task Force exhaustively analyzes all relevant medical studies and develops guidelines regarding which tests are appropriate for screening. It is not funded by any who might benefit from its recommendations (except the American taxpayers), and it has stringent procedures to help avoid bias. Its recommendations are graded from A to E, based on the level of evidence of help or harm from the tests. “A” indicates the most assuredly helpful tests, “E” the most harmful. Its breast cancer screening recommendation reads: “The USPSTF recommends (every other year) screening mammography for women aged 50 to 74 years.” This is a grade B recommendation, meaning members think it is pretty good, but are not absolutely sure.

For women under age 50, they say: “The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient’s values regarding specific benefits and harms.” This is a grade C recommendation, meaning they really can’t say whether this test is helpful or harmful. Previously they had indicated women generally should not get mammograms before age 50, indicating the harms probably outweigh the benefit. But they were pushed to change their wording because of the huge political outcry.

There is much room for opinion about when and how often to screen, but there is increasing consensus that we must consider the harms of screening, too. Mammograms clearly are associated with harms as well as benefits. The USPSTF recommendations are probably the best we have, given the current level of knowledge.

Neil Hall, M.D.

Cary

The length limit was waived to permit a fuller response to the Point of View.

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