Two models for radiological reviewing of interval cancers

Area of Science:

• Radiology
• Oncology
• Public Health

Background:

• Interval breast cancers are those diagnosed after a negative screening mammogram but before the next scheduled screening.
• Accurate identification of missed cases is crucial for improving mammography screening effectiveness and reducing observer error.

Purpose of the Study:

• To compare two distinct review methods for assessing interval breast cancers.
• To determine the proportion of interval cancers that could be classified as missed cases due to observer error.

Main Methods:

• A review of screening mammograms from 104 interval breast cancer cases identified during a mass screening program (1989-1991) in Stockholm.
• Mammograms were reviewed using two methods: mixed (with other screening images) and non-mixed, by both internal and external reviewers.

Main Results:

• The proportion of missed cases varied significantly (7%-34%) based on the review method and the number of reviewers.
• Mixed reviewing decreased the identification of missed cases by 50% compared to non-mixed reviewing.
• Reviewer's affiliation (internal vs. external) did not influence the results.

Conclusions:

• Comparing missed case rates across studies is unreliable without consistent review methodologies.
• Radiologist experience with their own screening unit's images did not affect detection rates.
• The majority of interval cancers were not classified as missed cases by either review method.