Interval breast cancers in an Australian mammographic screening program

Area of Science:

• Oncology
• Radiology
• Public Health

Background:

• Mammographic screening aims to detect breast cancer early, reducing mortality.
• Interval cancers, diagnosed between screenings, are a key metric for evaluating screening program effectiveness.
• Understanding interval cancer rates is crucial for assessing the overall impact of mammography services.

Purpose of the Study:

• To determine the incidence of interval breast cancers within 12 months following mammographic screening.
• To evaluate the quality of a specific mammographic screening service in Sydney.
• To compare interval cancer rates with established screening trials.

Main Methods:

• Retrospective analysis of data from the BreastScreen NSW Central & Eastern Sydney Service.
• Crossmatching screening data with the New South Wales Central Cancer Registry.
• Analysis of women aged 40-69 years screened between March 1988 and December 1992.

Main Results:

• The 12-month interval-cancer incidence was 4.17 per 10,000 screens for women aged 40-49 and 4.64 for women aged 50-69.
• Proportional incidence rates were 30.1% (40-49 years) and 22% (50-69 years).
• No significant difference was found when compared to major overseas screening trials for the 50-69 age group.

Conclusions:

• The mammographic screening quality in this service is acceptable and expected to reduce mortality.
• Comparisons of interval cancer data between programs and trials require careful consideration of age-specific data and confidence intervals.
• The findings support the continued use of mammographic screening for breast cancer detection.