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Danish Study Finds an Increased Risk of Developing Breast Cancer in Women With Previous False-Positive Mammography

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Key Points

  • A recent Danish study found that after excluding cases of misclassification, women with a false-positive mammography result had a 27% increased risk of developing breast cancer.
  • Women with false-positive results from surgical biopsies had a 30% increased risk.
  • The reasons why women with a false-positive test are more susceptible to developing breast cancer remain unclear.

Although studies have shown that women with a false-positive result from mammography screening have an increased risk of developing breast cancer later in life compared with women who only have negative results, a new Danish study examined how much of the excess risk was due to misclassification (ie, women who were actually false-negatives instead of false-positives). The researchers found that after excluding cases of misclassification, women with a false-positive result had a 27% increased risk of developing breast cancer. Women with false-positive results from surgical biopsies had a 30% increased risk. The reason is still unclear. The study by Euler-Chelpin et al is published in Cancer Epidemiology.

Study Methodology

The researchers analyzed data from the Copenhagen Mammography Screening Programme in Denmark of a total of 58,003 participants who had been screened between 1991 and 2005. The researchers identified 4,743 women who had been recalled due to suspicious findings. In 2008, 295 of the women had been diagnosed with breast cancer. The researchers then studied the cancers that developed in the same location as the finding that initially caused the recall to establish whether there had been misclassification.

Results

After radiologists reexamined the original mammograms, they found that 72 of the 295 women had been misclassified. After excluding the misclassified tests, however, the researchers found that the women with false-positive results were 27% more likely to be diagnosed with cancer years later (RR = 1.27, 95% confidence interval [CI] = 1.11–1.46), compared with women with only negative test results. In addition, those women with false-positive results determined at surgery had an excess risk of 30%.

“The results indicate that the increased risk is not explained only by misclassification,” concluded the researchers. “The excess risk remains for false-positive determined at assessment as well as at surgery, which favors some biological susceptibility. Further research into the true excess risk of false-positives is warranted.”

My von Euler-Chelpin, PhD, of the University of Copenhagen, and Megumi Kuchiki, and Ilse Vejborg, MD, of University Hospital of Copenhagen, Rigshospitalet, are the corresponding authors for the Cancer Epidemiology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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