She added that the study’s results, unfortunately, are not surprising.

“We are increasingly realizing in clinical medicine that the more we look, the more we find,” she said in the podcast interview. “And, since the introduction of screening mammography, we have seen a dramatic increase in new cases of ductal carcinoma in situ and early stage invasive breast cancer.”

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One caveat is that the authors used an ecological study design, which Dr. Elmore explained as being “great for hypothesis generating” but not designed for determining the exact percentage of women who were overdiagnosed.

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The USPSTF is reviewing draft recommendations for breast cancer screening that propose biannual routine screening of average-risk women beginning at age 50 and ending at age 74.

“The decision to start regular mammography screening before age 50 is an individual one—based on a woman’s values, preferences, and health history—and should be made in partnership between women and their doctors,” the USPSTF stated. The American Cancer Society recommends annual mammography screening beginning at age 40.

“To ensure that high quality cancer screening decisions are being made, a fully informed patient should participate in a shared decision-making process with their clinician,” Dr. Elmore told Cancer Therapy Advisor

“This is easier said than done, however. As a physician, I see patients in clinic and have a hard time navigating our busy schedules and the many demands on our time. It helps me immensely when my patients have investigated topics before coming to clinic so that they have considered evidence and also their own personal values. The use of decision aides from trusted groups can be quite helpful and improve patients’ quality of decisions.”

Harding said the study results have shown it is important to establish the right rate of screening, so screenings are not performed too frequently or too infrequently. Given the differing risks among women of developing breast cancer, identifying subgroups of women who may have an elevated risk—or decreased risk—of overdiagnosis is key.


  1. Harding C, Pompei F, Burmistrov D, et al. Breast cancer screening, incidence, and mortality across US counties. JAMA Intern Med. [Epub ahead of print] doi: 10.1001/jamainternmed.2015.3043.
  2. US Preventive Services Task Force. Breast cancer screening draft recommendations. Available at: Accessed July 7, 2015.
  3. Elmore JG, Etzioni R. Effect of screening mammography on cancer incidence and mortality. JAMA Intern Med. [Epub ahead of print] doi: 10.1001/jamainternmed.2015.3056.