A study from the U.K. suggests that lower levels of recall for suspicious findings on screening mammography are linked with higher rates of interval breast cancers detected between screenings, which are associated with a worse prognosis than screen-detected cancers.
The study provides evidence of the potential importance of establishing a minimum recall rate for breast cancer screening programs, the researchers say.
Calling women back for additional testing after suspicious mammography findings helps safeguard against missing invasive breast cancers, but carries costs, including anxiety for the patient and added healthcare expenditures, Dr. Elizabeth Burnside from the University of Wisconsin in Madison with colleagues in the U.K. note in a paper released April 3 by the journal Radiology.
The U.K. has established a maximum recall rate target of less than 7% for a patient's first (or prevalent) screening and less than 5% for incident screens (those in which previous screening results exist). But there is no consensus on a minimum recall rate, below which additional cancers would be missed.
Dr. Burnside and colleagues designed their study to see whether low levels of recall lead to more interval cancers. They analyzed roughly 5.1 million screening episodes from 84 U.K. screening centers over a 36-month period, with a three-year follow-up in women aged 50 to 70 years.
In this cohort, the recall rate averaged 4.56%, with a cancer detection rate of 8.1 per 1,000 women screened and an interval cancer rate of 3.1 per 1,000 women screened.
Overall results showed a "significant negative association" between recall rate and interval cancer rate (P=0.001), with roughly one fewer interval cancer for every additional 80 to 84 recalls.
Subgroup analysis found similar negative correlations in women aged 50 to 54 (P=0.002), 60 to 64 (P=0.01), and 65 to 69 (P=0.008) but not in women aged 55 to 59 years (P=0.46). Negative correlations were present in both incident screens (P=0.001) and prevalent screens (P=0.04).
The study found a "consistent and statistically significant" association between increasing recall rate and decreasing interval cancer rate, the researchers write. “These findings persist in most age groups and for both prevalent and incident rounds.”
"There is consensus that a maximum recall threshold exists, above which diminishing benefits of screening mammography accrue relative to added harms; this study provides evidence that there is also likely a minimal recall threshold, below which some potential benefits of screening mammography are lost," write the researchers.
They say more study is needed to determine a specific minimum threshold for recall rate and evaluate the impact of digital mammography on the relationship between recall rate and interval cancers.
The study also underscores the importance of collecting comprehensive and accurate data on interval cancers in national screening programs.
"A big-picture lesson in our study is the power of rigorous quality assurance infrastructure to help breast cancer screening programs learn from actual practice and use that information to make informed programmatic decisions for the future," Dr. Burnside said.
The study had no commercial funding and the authors have declared no conflicts of interest.
SOURCE: http://bit.ly/2IoAaQL
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