Does a False Positive Mammogram Indicate Future Breast Cancer?

Nurse explaining mammogram to patient
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All screening tests carry the risk of false-positive results. A screening mammography is no exception. When a mammogram shows an abnormal area that looks like a cancer, but turns out to be normal, it’s called a false-positive. False-positive results from screening mammograms are less common since the wide-spread use of digital mammography.

Getting a call that a routine mammogram found something that needs further screening will usually cause a great deal of anxiety. When a screening mammography results in a positive finding, one or more additional screenings such as ultrasound, MRI, PET, or surgical biopsy are usually performed to determine whether or not a cancer is present. Such follow up tests may be painful, at least uncomfortable, and increase anxiety in the weeks that follow the original false-positive diagnosis and the pathology report indicating no evidence of disease.

Some women, initially relieved to hear they are cancer free, become angry about what the false-positive screening costs them financially and emotionally.  Some often decide to avoid having mammograms in the future.

The U.S. Preventive Services Task Force, in 2009, recommended beginning mammograms at 50 instead of 40 years of age. More recently, the American Cancer Society modified their screening guidelines for mammography recommended that women begin screenings at 45 years of age. They cited the incidents of false-positives and the anxiety, expense, and pain that they cause as one of the reasons for changing the age for beginning mammograms. The medical community reacted with concern to these changes given the number of women, in their 40’s diagnosed with breast cancer annually, and those going into the 50+ population with undetected breast cancers.  Breast cancers that occur before menopause are often more aggressive.

The Journal of the National Cancer Institute, gives a new perspective on the significance of false-positives based on the results of a recent study conducted in Denmark. The study, conducted in Copenhagen, suggests that a false-positive finding on mammography indicates a greater chance of breast cancer long-term, due to underlying pathology or initial misclassification.

The study reviewed screening outcomes of 58,003 women, ages 50 to 69, who participated in Copenhagen’s population-based mammography screening program during the years 1991-2005.

The study reported that women getting any kind of false-positive results had an adjusted 67% higher risk of getting a breast cancer after a false-positive than women having had only negative mammograms. Researchers noted that the risk, following a false positive, continued to be elevated for upwards of 12 years.

Study researchers stated, “Women with false-positive tests manifest suspicious mammography patterns in their breast tissue, including tumor-like masses, suspicious calcifications, skin thickening or retraction, recently retracted nipples, distortions, asymmetric densities, or suspicious axillary lymph nodes. Despite a thorough assessment to exclude malignancies at baseline, these suspicious patterns in breast tissue may eventually develop into detectable cancer.”

Researchers recommended encouraging women with false-positive tests to continue to receive regular screenings, even though it could cause extra anxiety.

To understand the impact of a false-positive mammogram, 1,028 women who had mammograms at 22 screening centers in the United States were randomly selected participated in a telephone survey on anxiety. Survey participants included 534 women that had negative mammogram results and 494 women with false-positive results.

The first part of the survey was done soon after the women were screened. The second part was a year after their mammograms. Of the women who got false-positive results, 50% reported anxiety levels that range from moderate to high.

 A year later, anxiety levels of women who had negative results and women who had false-positive results were the same. False-positive results seemed to have no effect on quality of life in the long run. Most of the women, with false-positive results, said they were likely to have a mammogram in the future.

What’s important to take away from this study? Don't let any obstacles, including fear of a false- positive, get in the way of your regular screening mammograms.

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Article Sources
  • Journal of the National Cancer Institute. JAMA Internal Medicine.