Screening for breast cancer with mammography

Area of Science:

• Oncology
• Public Health
• Radiology

Background:

• Estimates of mammographic screening benefits and harms vary.
• National breast cancer screening policies differ.
• Assessing the true impact of screening is crucial.

Purpose of the Study:

• To evaluate the effect of mammographic screening on breast cancer mortality.
• To assess the impact of screening on breast cancer morbidity.
• To provide evidence for informed screening decisions.

Main Methods:

• Systematic review of randomized trials comparing mammography screening with no screening.
• Searched PubMed up to November 2008.
• Independent data extraction and contact with study authors for clarification.

Main Results:

• Seven eligible trials included 600,000 women; one biased trial was excluded.
• Adequately randomized trials showed no significant reduction in breast cancer mortality at 13 years.
• Screening increased lumpectomies and mastectomies (RR 1.31) and radiotherapy use.

Conclusions:

• Mammographic screening likely reduces breast cancer mortality by an estimated 15% (0.05% absolute risk reduction).
• Screening results in 30% overdiagnosis and overtreatment (0.5% absolute risk increase).
• The balance of benefits and harms, including psychological distress from false positives, remains unclear.