Double reading in breast cancer screening associated with reduced recall rates, improved cancer detection

Mammography interpreted by two radiologists instead of one can lead to reduced recall rates and improved cancer detection, according to a new study published in Radiology. However, the authors noted, any additional cancers detected require “careful consideration” as they may be smaller, less likely to be invasive or less likely to have involved nodes.

The authors noted that, as opposed to the United States, mammograms are interpreted by two readers in many European countries. The study included data from more than 805,000 women screened as part of England’s National Health Service Breast Screening Program. Reading was performed by two radiologists, and “expert arbitration” occurred the two readers disagreed about if a patient should be recalled or not. Overall, the first reader recalled 4.76 percent of women and the two readers recalled 6.19 percent of women. After arbitration, the final recall rate was 4.08 percent.

Of more than 7,000 cancers detected, more than 8 percent were only detected by the second radiologist. These additional cancers had an increased likelihood of being ductal carcinoma in situ and additional cancers determined to be invasive were smaller than other invasive cancers detected in the study.

“The extra cancers detected were smaller and lower grade and were less likely to be invasive or have involved nodes,” wrote lead author Sian Taylor-Phillips, PhD, from Warwick Medical School in Coventry, England, and colleagues. “Detecting these extra cancers may be associated with detecting important pathologic findings earlier, but it may also be associated with increased overdiagnosis from screening. Further analysis of follow-up data on outcomes is required to understand the balance of the benefits and harms of detecting these extra cancers. Policy makers should consider the overall harms and benefits when deciding whether to use a second reader, bearing in mind that a single reader might not perform the same way a first reader working as part of a team might.”

The authors noted that their study did have limitations. For instance, the authors assumed that the actions of the first reader would match up with the actions of a radiologist acting as an exam’s only reader. “Readers working alone may operate at a different standard or recall threshold if there is no second reader to pick up missed cancers and no arbitration to reduce false-positive recalls,” the authors wrote.